Question
How do you delete a Cookie within a JSP? (JSP)
Answer
Cookie mycook = new Cookie("name","value");
response.addCookie(mycook);
Cookie killmycook = new Cookie("mycook","value");
killmycook.setMaxAge(0);
killmycook.setPath("/");
killmycook.addCookie(killmycook);
Question
How many types of protocol implementations does RMI have? (RMI)
Answer
RMI has at least three protocol implementations: Java
Remote Method Protocol(JRMP), Internet Inter ORB Protocol(IIOP),
and Jini Extensible Remote Invocation(JERI). These are alternatives,
not part of the same thing, All three are indeed layer 6 protocols for
those who are still speaking OSI reference model.
Question
What are the different identifier states of a Thread?
(Core Java)
Answer
The different identifiers of a Thread are:
R - Running or runnable thread
S - Suspended thread
CW - Thread waiting on a condition variable
MW - Thread waiting on a monitor lock
MS - Thread suspended waiting on a monitor lock
Question
What is the fastest type of JDBC driver? (JDBC)
Answer
JDBC driver performance will depend on a number of
issues:
(a) the quality of the driver code,
(b) the size of the driver code,
(c) the database server and its load,
(d) network topology,
(e) the number of times your request is translated to a different API.
In general, all things being equal, you can assume that the more your
request and response change hands, the slower it will be. This
means that Type 1 and Type 3 drivers will be slower than Type 2
drivers (the database calls are make at least three translations versus
two), and Type 4 drivers are the fastest (only one translation).
Question
Request parameter How to find whether a parameter
exists in the request object?
(Servlets)
Answer
1.boolean hasFoo = !(request.getParameter("foo") ==
null || request.getParameter("foo").equals(""));
2. boolean hasParameter =
request.getParameterMap().contains(theParameter);
(which works in Servlet 2.3+)
Question
How can I send user authentication information while
makingURLConnection?
(Servlets)
Answer
You’ll want to use
HttpURLConnection.setRequestProperty and set all the appropriate
headers to HTTP authorization.
Question
How do I convert a numeric IP address like 192.18.97.39
into a hostname like java.sun.com?
(Networking)
Answer
Question
How many methods do u implement if implement the
Serializable Interface?
(Core Java)
Answer
The Serializable interface is just a "marker" interface,
with no methods of its own to implement. Other ’marker’ interfaces
are
java.rmi.Remote
java.util.EventListener
String hostname =InetAddress.getByName("192.18.97.39").getHostName();
posted @
2010-10-25 17:08 Sun River|
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1.
Question
What is the query used to display all tables names in
SQL Server (Query analyzer)?
(JDBC)
Answer
select * from information_schema.tables
Question
What is Externalizable? (Core Java)
Answer
Externalizable is an Interface that extends Serializable
Interface. And sends data into Streams in Compressed Format. It has
two methods, writeExternal(ObjectOuput out) and
readExternal(ObjectInput in).
Question
What modifiers are allowed for methods in an Interface?
Answer
Only public and abstract modifiers are allowed for
methods in interfaces.
Question
How many types of JDBC Drivers are present and what
are they?
(JDBC)
Answer
There are 4 types of JDBC Drivers
Type 1: JDBC-ODBC Bridge Driver
Type 2: Native API Partly Java Driver
Type 3: Network protocol Driver
Type 4: JDBC Net pure Java Driver
Question
What is the difference between ServletContext and
PageContext?
(JSP)
Answer ServletContext: Gives the information about the container
PageContext: Gives the information about the Request.
Question
How to pass information from JSP to included JSP?
Answer Using <%jsp:param> tag.
posted @
2010-10-25 16:07 Sun River|
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tomcat6配置双向认证
1、生成服务器端证书
keytool -genkey -keyalg RSA -dname "cn=localhost,ou=sango,o=none,l=china,st=beijing,c=cn" -alias server -keypass password -keystore server.jks -storepass password -validity 3650
2、生成客户端证书
keytool -genkey -keyalg RSA -dname "cn=sango,ou=sango,o=none,l=china,st=beijing,c=cn" -alias custom -storetype PKCS12 -keypass password -keystore custom.p12 -storepass password -validity 3650
客户端的CN可以是任意值。
3、由于是双向SSL认证,服务器必须要信任客户端证书,因此,必须把客户端证书添加为服务器的信任认证。由于不能直接将PKCS12格式的证书库导入,我们必须先把客户端证书导出为一个单独的CER文件,使用如下命令,先把客户端证书导出为一个单独的cer文件:
keytool -export -alias custom -file custom.cer -keystore custom.p12 -storepass password -storetype PKCS12 -rfc
然后,添加客户端证书到服务器中(将已签名数字证书导入密钥库)
keytool -import -v -alias custom -file custom.cer -keystore server.jks -storepass password
4、查看证书内容
keytool -list -v -keystore server.jks -storepass password
5、配置tomcat service.xml文件
<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
maxThreads="150" scheme="https" secure="true"
clientAuth="true" sslProtocol="TLS"
keystoreFile="D:/server.jks" keystorePass="password"
truststoreFile="D:/server.jks" truststorePass="password"
/>
clientAuth="true"表示双向认证
6、导入客户端证书到浏览器
双向认证需要强制验证客户端证书。双击“custom.p12”即可将证书导入至IE
tomcat6配置单向认证
1、生成服务器端证书
keytool -genkey -keyalg RSA -dname "cn=localhost,ou=sango,o=none,l=china,st=beijing,c=cn" -alias server -keypass password -keystore server.jks -storepass password -validity 3650
2、由于是单向认证,没有必要生成客户端的证书,直接进入配置tomcat service.xml文件
<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
maxThreads="150" scheme="https" secure="true"
clientAuth="false" sslProtocol="TLS"
keystoreFile="D:/server.jks" keystorePass="password"
/>
clientAuth="false"表示单向认证,同时去掉truststoreFile="D:/server.jks" truststorePass="password"这2
posted @
2010-05-11 12:12 Sun River|
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---The key thing to know is that IDs identify a specific element and therefore must be unique on the page – you can only use a specific ID once per document. Many browsers do not enforce this rule but it is a basic rule of HTML/XHTML and should be observed. Classes mark elements as members of a group and can be used multiple times, so if you want to define a style which will be applied to multiple elements you should use a class instead.
Notice that an ID's CSS is an HTML element, followed by a "#", and finally ID's name. The end result looks something like "element#idname". Also, be sure to absorb the fact that when an ID is used in HTML, we must use "id=name" instead of "class=name" to reference it!
Why Did They Choose Those Names??
ID = A person's Identification (ID) is unique to one person.
Class = There are many people in a class.
ID for Layout and Uniqueness
Standards specify that any given ID name can only be referenced once within a page or document. From our experience, IDs are most commonly used correctly in CSS layouts. This makes sense because there are usually only one menu per page, one banner, and usually only one content pane.
In Tizag.com CSS Layout Examples we have used IDs for the unique items mentioned above. View the CSS Code for our first layout example. Below are the unique IDs in our code.
Menu - div#menuPane
Content - div#content
Answer: Classes vs IDs
Use IDs when there is only one occurence per page. Use classes when there are one or more occurences per page.
posted @
2010-03-16 10:14 Sun River|
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--Spring的singleton是容器级的,我们一般说的singleton模式是JVM级的。所以singleton模式中,singleton的class在整个JVM中只有一个instance,Spring的Bean,你可以一个class配置多个Bean,这个class就有了多个instance。这个singleton是指在spring容器中,这个Bean是单实例的,是线程共享的。所以要求这些类都是线程安全的。也就是说,不能出现修改Bean属性的方法,当然除了设值得那些setter。只要满足线程安全,这些bean都可以用singleton。而且我们在绝大多数使用上,也是这样用的,包括dao,service。
Beanfactory是Spring初始以静态方式载入的,Spring的单例IOC是基于容器级的,所以这你都不用担心与考虑.
--应用中对象有两种,行为对象和数据对象,行为对象都要求是线程安全的!也就是允许单例的, 不管是dao 还是 service 对象,都是行为对象,行为对象不应该引用非线程安全的对象做成员量,同时在应用外部的资源(如文件,数据库连接,session)时,要先保证对这些东西的访问是做了并发控制的!
对于spring来讲,<bean scope="singleton"/>或<bean singleton="true"/>都是保证对同一sesionfactory bean是单例的,也就是所谓 sessionfactory 范围的.
--这是一个真实的案例,我们在项目中使用Spring和ACEGI,我之所以选择ACEGI,除了它对权限的良好控制外,
我还看好它的SecurityContextHolder,通过代码
代码
- Authentication auth = SecurityContextHolder.getContext().getAuthentication();
<script>render_code();</script>
我可以很容易在系统任意一层得到用户的信息,而不用把用户信息在参数里传来传去,(这也是struts的缺点之一)
但是我在每一次要得到用户信息的时候都写上面的一段代码,未免有些麻烦,所以我在BaseService, BaseDao里都提供了如下方法:
代码
-
-
-
-
- protected UserInfo getUserInfo()
- {
- return getUserContext().getUserInfo();
- }
-
-
-
-
-
- protected UserContext getUserContext()
- {
- Authentication auth = SecurityContextHolder.getContext().getAuthentication();
- return (UserContext) auth.getPrincipal();
- }
<script>render_code();</script>
这样在其他的Service和Dao类里可以通过
代码
- super.getUserContext(), super.getUserInfo()
<script>render_code();</script>
来得到用户的信息,这也为问题的产生提供了温床。请看如下代码:
代码
- public class SomeServece extends BaseService implements SomeInterFace
- {
- private UserInfo user = super.getUserInfo();
-
- public someMethod()
- {
- int userID = this.user.getUserID();
- String userName = this.user.getUserName();
-
- }
- }
<script>render_code();</script>
这段代码在单元测试的时候不会用任何问题,但是在多用户测试的情况下,你会发现任何调用SomeService里someMethod()方法
的userID和userName都是同一个人,也就是第一个登陆的人的信息。Why?
其根本原因是Spring的Bean在默认情况下是Singleton的,Bean SomeServece的实例只会生成一份,也就是所SomeServece实例的user
对象只会被初始化一次,就是第一次登陆人的信息,以后不会变了。所以BaseService想为开发提供方便,却给开发带来了风险
正确的用法应该是这样的
代码
- public class SomeServece extends BaseService implements SomeInterFace
- {
-
-
- public someMethod()
- {
- int userID = super.getUserInfo().getUserID();
- String userName = super.getUserInfo().getUserName();
-
- }
posted @
2009-04-08 12:12 Sun River|
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Architect (Java) Interview Questions
General and general terms questions
Architect interview is slightly different from all other interview types. Interviewer is looking for ability of the candidate to think independently on top of pure technical knowledge. Most of the questions are open-ended, prompting the interviewee to discussion about different aspects of Java development. Other side of the interview is general questions about position of the architect within the organization. Some questions do not have clear, direct or single answer and require discussion with the interviewer. On top of questions mentioned here you may be asked generic OO questions (what is class, what is polymorphism etc.)
- What distinguishes "good architecture" from "bad architecture"?
This is an open-ended question. There are few aspects of "good" architecture:
- Shall address functional product requirements
- Shall address non-functional product requirements, such as performance, scalability, reliability, fault tolerance, availability, maintainability, extensibility
- Shall be simple and comprehendible (to support maintainability and extensibility)
- Shall be well structured (support multiple tiers, parallel development etc.)
- Shall be detailed enough to share with different levels of organizational structure (marketing, sales, development, management)
"Bad" architecture is basically opposite to "good" architecture.
- How much experience do you have with Enterprise applications? Another variant of this questions is: "Tell me about projects where you worked with J2EE?" Yet another version: "What, when and how made using EJB?"
Interviewer is looking for your experience with designing J2EE applications and your experience with J2EE technologies and general terms. This is often start of the discussion and bridge to the technical section of the questions.
- What is scalability?
- What is high-availability? How is it different from scalability?
- What is the fault tolerance?
- What resources are used to keep up to date with J2EE technology?
Specific technical questions
- What modeling tools you are familiar with? What version of TogetherJ (Rational Rose etc.) have you used?
- If stateless session bean more scalable than stateful session beans?
This is very popular questions that leads to some confusion. According to the second edition of "Core J2EE Patterns" and contrary to popular belief, stateful session beans are not less scalable than stateless session bean. The reason for that is life cycle of either type is controlled by Application Server and control of life cycle is what defines the scalability of the application
- What's the difference between EJB 1.1 and EJB 2.0?
There are many differences. Some key points you want to mention are:
- New CMP model
- EJB Query Language
- Local interfaces
- EJBHome methods
- Message Driven Beans (MDB) support
- What transaction isolation levels do you know?
none, repeatable read, read committed, read uncommitted, serializable
- What transaction attributes do you know?
requires new, required, supports, not supported, mandatory, never
- What is the difference between optimistic lock and pessimistic lock?
Optimistic lock is an implicit lock that tries to make best assumption about locking strategy and minimize time spent in lock of resource. Optimistic lock is usually implemented with some kind of timestamp strategy. Pessimistic lock is an explicit lock that set by client.
- What are entity beans. Are there any issues with them?
Typical reaction to this question is very expressive answer that entity beans should not be used. There are many performancy implications with entity beans if used incorrectly. One of the famous problems are "n+1 call problem" Inter-entity bean call is very expensive operation and should be avoided.
- What core design patterns do you know?
Architect must know at least some basic design patters used in J2EE development, e.g. Business Delegate, Session Facade, VO, List Handler, DTO, Composite Entity, etc.
- Where business logic should reside?
Typical answer is "in business tier" This usually opens series of questions like: What is business logic, how to determine business logic, how business logic is different from persistent logic etc.
- What is JDO?
JDO is Java Data Object - persistent framework that is alternative to idea of entity beans
- What is the difference between JSP and servlet? When to use what?
JSP is compiled into servlet. JSP are better suit to view of information, while servlets are better for controlling stuff.
- Does the J2EE platform support nested transactions?
No.
- Can you use synchronization primitives in my enterprise beans?
No.
- Why all major application server vendors provide custom class loaders in addition to system jvm class loader?
System one does not support hot deployment.
Performance questions
- What are performance problems in J2EE and how to solve them?
- What are Entity beans performance pitfalls?
- What performance pattern do you know?
Design Pattern questions
- Can you use singleton in EJB?
Yes, but should not (explain why)
- What is MVC pattern and why M, V and C need to be separated?
- Describe Business Delegate pattern (or any other pattern)
- How to prevent double submission of the form from JSP page? (or describe Synchronizer Token pattern)
posted @
2009-03-17 11:51 Sun River|
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Interview Questions on UML and Design Patterns
Why to use design patterns?
Give examples of design patterns?
What is UML?
What are advantages of using UML?
What is the need for modelling?
Is it requiste to use UML in software projects?
What are use cases? How did you capture use cases in your project?
Explain the different types of UML diagrams ? sequence diagram , colloboration diagram etc
What is the sequence of UML diagrams in project?
What tools did you use for UML in your project?
What is the difference between activity and sequence diagrams?
What are deployment diagrams?
What are the different object relationships ?
What is the difference between composition and aggregation?
Wheel acting as a part of car ? Is this composition or aggregation?
posted @
2009-03-17 11:43 Sun River|
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spring与自动调度任务(一)
面是自己自动调度的一些学习。
这里只采用jdk自带的timer进行的,准备在下篇文章中用Quartz调度器。
首先建立你自己要运行的类。
package com.duduli.li;
public class Display {
public void disp(){
System.out.println("自动控制测试");
}
}
一个简单的java bean,其中在这里你可以替换自己的任务。
然后就是编写调度程序,这里要继承jdk中的TimerTask类,复写他的run方法。
package com.duduli.li;
import java.util.TimerTask;
public class AutoRan extends TimerTask {
//set方法是spring的DI
private Display display;
public void setDisplay(Display display) {
this.display = display;
}
@Override
public void run() {
display.disp();
}
}
然后就是重要的一步,编写applicationsContext.xml了。
<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean id="display"
class="com.duduli.li.Display">
</bean>
<bean id="atuoRun"
class="com.duduli.li.AutoRan">
<property name="display" ref="display"></property>
</bean>
<bean id="aR"
class="org.springframework.scheduling.timer.ScheduledTimerTask">
<property name="timerTask" ref="atuoRun"></property>
<!--
period多长时间运行一次,delay表示允许你当任务第一次运行前应该等待多久
-->
<property name="period" value="5000"></property>
<property name="delay" value="2000"></property>
</bean>
<bean id="test"
class="org.springframework.scheduling.timer.TimerFactoryBean">
<property name="scheduledTimerTasks">
<list>
<!--
这里使用list,可以调度多个bean,
-->
<ref bean="aR"/>
</list>
</property>
</bean>
</beans>
再来就是客户端调度了。
package com.duduli.li;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Client {
public static void main(String[] args) {
BeanFactory factory = new ClassPathXmlApplicationContext("applicationContext.xml");
factory.getBean("test");
}
}
spring与自动调度任务(二)
使用quartz和spring自动调度。
具体实现bean:
package com.duduli.li.quartz;
import java.util.Date;
public class Display {
@SuppressWarnings("deprecation")
public void disp(){
System.out.println(new Date().getSeconds());
System.out.println("自动控制测试");
}
}
继承quartzjobbean类:这个类和继承Timer类类似
。
package com.duduli.li.quartz;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import org.springframework.scheduling.quartz.QuartzJobBean;
public class AutoRun extends QuartzJobBean{
private Display display;
public void setDisplay(Display display) {
this.display = display;
}
@Override
protected void executeInternal(JobExecutionContext arg0)
throws JobExecutionException {
display.disp();
}
}
spring配置文件:
<!-- quartz进行自动调度 -->
<!-- 具体实现类 -->
<bean id="display2" class="com.duduli.li.quartz.Display"></bean>
<!-- spring对quartz的支持,Auto类实现quartz的job接口的类,jobDataAsMap是将实现类注入其中 -->
<bean id="quartz" class="org.springframework.scheduling.quartz.JobDetailBean">
<property name="jobClass" value="com.duduli.li.quartz.AutoRun"/>
<property name="jobDataAsMap">
<map>
<entry key="display" value-ref="display2"></entry>
</map>
</property>
</bean>
<!-- spring对quartz的支持,对其值的设定 -->
<bean id="simpleTask" class="org.springframework.scheduling.quartz.SimpleTriggerBean">
<property name="jobDetail" ref="quartz"></property>
<property name="startDelay" value="2000"></property>
<property name="repeatInterval" value="2000"></property>
</bean>
<!-- 启动自动调度 -->
<bean id="quartzTest" class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
<property name="triggers">
<list>
<ref bean="simpleTask"/>
</list>
</property>
</bean>
client调用:
package com.duduli.li.quartz;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Client {
public static void main(String[] args) {
BeanFactory factory = new ClassPathXmlApplicationContext("applicationContext.xml");
factory.getBean("quartzTest");
}
}
posted @
2009-03-12 12:42 Sun River|
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Java implements a very efficient interprocess communication which reduces the CPU’s idle time to a very great extent. It is been implemented through wait ( ), notify ( ) and notifyAll ( ) methods. Since these methods are implemented as final methods they are present in all the classes.
The basic functionality of each one of them is as under:
■ wait( ) acts as a intimation to the calling thread to give up the monitor and go to sleep until some other thread enters the same monitor and calls notify( ).
■ notify( ) is used as intimator to wake up the first thread that called wait( ) on the same object.
■ notifyAll( ) as the term states wakes up all the threads that called wait( ) on the same object. The highest priority thread will run first.
public class WaitNotifyAllExample {
public static void main(String[] args) {
try {
Object o = new Object();
Thread thread1 = new Thread(new MyOwnRunnable("A", o));
Thread thread2 = new Thread(new MyOwnRunnable("B", o));
Thread thread3 = new Thread(new MyOwnRunnable("C", o));
// synchronized keyword acquires lock on the object.
synchronized (o) {
thread1.start();
// wait till the first thread completes execution.
// thread should acquire the lock on the object
// before calling wait method on it. Otherwise it will
// throw java.lang.IllegalMonitorStateException
o.wait();
thread2.start();
// wait till the second thread completes execution
o.wait();
thread3.start();
}
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class MyOwnRunnable implements Runnable {
private String threadName;
private Object o;
public MyOwnRunnable(String name, Object o) {
threadName = name;
this.o = o;
}
public void run() {
synchronized (o) {
for (int i = 0; i < 1000; i++) {
System.out.println("Thread " + threadName + " Count : " + i);
}
// notify all threads waiting for the object o.
// thread should acquire the lock on the object
// before calling notify or notifyAll method on it.
// Otherwise it will throw java.lang.IllegalMonitorStateException
o.notifyAll();
}
}
}
posted @
2009-03-12 12:09 Sun River|
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posted @
2009-03-10 11:42 Sun River|
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What are JavaScript types? - Number, String, Boolean, Function, Object, Null, Undefined.
- How do you convert numbers between different bases in JavaScript? - Use the parseInt() function, that takes a string as the first parameter, and the base as a second parameter. So to convert hexadecimal 3F to decimal, use parseInt ("3F", 16);
- What does isNaN function do? - Return true if the argument is not a number.
- What is negative infinity? - It’s a number in JavaScript, derived by dividing negative number by zero.
- What boolean operators does JavaScript support? - &&, || and !
- What does "1"+2+4 evaluate to? - Since 1 is a string, everything is a string, so the result is 124.
- How about 2+5+"8"? - Since 2 and 5 are integers, this is number arithmetic, since 8 is a string, it’s concatenation, so 78 is the result.
- What looping structures are there in JavaScript? - for, while, do-while loops, but no foreach.
- How do you create a new object in JavaScript? - var obj = new Object(); or var obj = {};
- How do you assign object properties? - obj["age"] = 17 or obj.age = 17.
- What’s a way to append a value to an array? - arr[arr.length] = value;
- What is this keyword? - It refers to the current object.
posted @
2009-03-10 11:37 Sun River|
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摘要:
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posted @
2009-03-10 11:36 Sun River|
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A SQL profile is sort of like gathering statistics on A QUERY - which involves many
tables, columns and the like....
In fact - it is just like gathering statistics for a query, it stores additional
information in the dictionary which the optimizer uses at optimization time to determine
the correct plan. The SQL Profile is not "locking a plan in place", but rather giving
the optimizer yet more bits of information it can use to get the right plan.
posted @
2009-01-28 11:14 Sun River|
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<SCRIPT LANGUAGE="JavaScript1.3">
//Enter-listener
if (document.layers)
document.captureEvents(Event.KEYDOWN);
document.onkeydown =
function (evt) {
var keyCode = evt ? (evt.which ? evt.which : evt.keyCode) : event.keyCode;
if (keyCode == 13) //13 = the code for pressing ENTER
{
document.form.submit();
}
}
</SCRIPT>
posted @
2008-04-23 12:11 Sun River|
编辑 收藏
My top javascripts
---. ExpandCollapse
Used for expanding and collapsing block elements. I use this one for hiding divs or expanding the divs for forms. Very useful.
function expandCollapse() {
for (var i=0; i<expandCollapse.arguments.length; i++) {
var element = document.getElementById(expandCollapse.arguments[i]);
element.style.display = (element.style.display == "none") ? "block" : "none";
}
}
<p><em>Example:</em></p>
<div id="on" style="border: 1px solid #90ee90;padding: 5px;">
<a href="javascript: expandCollapse('expand', 'on');">Expand Layer</a>
</div>
<div id="expand" style="display: none;border: 1px solid #90ee90;padding: 5px;">
<a href="javascript: expandCollapse('expand', 'on');">Collapse Layer</a>
<p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Quisque eu ligula. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos hymenaeos. Ut wisi. Curabitur odio. Sed ornare arcu id diam. Integer ultricies, mauris venenatis vulputate pulvinar</p>
</div>
--Timer Layer
Used for hiding an element after ‘x’ of seconds. Great for hiding status messages after a person has submitted a form.
var timerID;
function ShowLayer(id)
{
document.getElementById().style.display = "block";
}
function HideTimedLayer(id)
{
clearTimeout(timerID);
document.getElementById(id). »
style.display = "none";
}
function timedLayer(id)
{
setTimeout("HideTimedLayer(""" + id + """)",»
5000); //5000= 5 seconds
}
--Form Checker
Probably one of the most useful scripts and there are several out there about form validation. This figures out what fields are required from the value in in a hidden input
tag. Than it highlights the error areas.
for (var j=0; j<myForm.elements.length; j++) {
var myElement = myForm.elements[j];
var isNull = false;
if (myElement.name == field && myElement.»
style.display != "none") {
if (myElement.type == "select-one" || »
myElement.type == "select-multiple") {
if ((myElement.options[myElement.selectedIndex].
»value == null || myElement.
»options[myElement.
»selectedIndex].value == '')
»&& errorString.indexOf(title) == -1) {
isNull = true;
}
} else if ((myElement.value == null ||
»myElement.value.search(/"w/)»
== -1) && errorString.indexOf(title) == -1) {
isNull = true;
}
if (isNull) {
errorString += title + ", ";
if (document.getElementById('label_'+myElement.name))»
{ document.getElementById('label_'+myElement.name)
».className="er"; }
myElement.className="erInput";
} else {
if (document.getElementById('label_'+myElement.name)) {
document.getElementById('label_'+myElement.name)
».className="s1";
}
myElement.className="s1";
}
}
}
}
if (errorString != '') {
errorString = errorString.slice(0,errorString.length-2);
window.alert("Please fill in the following
»required fields before submitting this form:"n"n"+errorString)
return false;
}
else {
return true;
}
}
---今天练习了一下用javascript做文字自动匹配的功能,类似于Google Suggest,当然人家Google是连接后台数据库,在网上不方便做连接数据库,所有功能在前台实现。在javascript里定义了一个全局数组arrCities用来存储一些城市的名字。然后当我们在文本输入框里输入某个城市名字的时候,每输入完一个字,就会拿当前的文字到arrCities数组里去比对,看是否存在于arrCities的某个成员里。若存在,就把该成员添加到紧靠文本输入框下面的组合列表框里,供我们选择,这样我们就不用完全输入完整个城市的名字,只要
从下面选择一个就可以完成想要做的工作。看下面的例子:
<html>
<head>
<title>Autosuggest Example</title>
<script type="text/javascript">
var arrCities=["北京","上海"];
arrCities.sort();
//控制是否显示层div1,bFlag为true则表示显示div1,为false则把div1从页面流里移除
function showDiv1(bFlag){
var oDiv=document.getElementById("div1");
if(bFlag){
oDiv.style.display="block";
}
else{
oDiv.style.display="none";
}
};
//给sel1添加option
function addOption(oListbox,sText){
var oOption=document.createElement("option");
oOption.appendChild(document.createTextNode(sText));
oListbox.appendChild(oOption);
};
//移除一个option
function removeOption(oListbox,iIndex){
oListbox.remove(iIndex);
};
//移除所有的option
function clearOptions(oListbox){
for(var i=oListbox.options.length-1;i>=0;i--){
removeOption(oListbox,i);
}
};
//设置select里的第一个option被选中
function setFirstSelected(oListbox){
if(oListbox.options.length>0){
oListbox.options[0].selected=true;
}
}
//获取匹配的字段
function getAutosuggestMatches(sText,arrValues){
var arrResult=new Array;
if(sText!=""){
for(var i=0;i<arrValues.length;i++){
if(arrValues[i].indexOf(sText)==0){
arrResult.push(arrValues[i]);
}
}
}
else{
showDiv1(false);
}
return arrResult;
};
//把匹配的字段添加到sel1中
function addSuggestOptions(oTextbox,arrValues,sListboxId,oEvent){
var oListbox=document.getElementById(sListboxId);
clearOptions(oListbox);
var arrMatches=getAutosuggestMatches(oTextbox.value,arrValues);
if(arrMatches.length>0){
showDiv1(true);
for(var i=0;i<arrMatches.length;i++){
addOption(oListbox,arrMatches[i]);
}
setFirstSelected(oListbox);
if(oEvent.keyCode==8){
oTextbox.focus();
}
else{
oListbox.focus();
}
}
};
//获取select里的option到textbox
function getSuggestText(oListbox,sTextboxId){
var oTextbox=document.getElementById(sTextboxId);
if(oListbox.selectedIndex>-1){
oTextbox.value=oListbox.options[oListbox.selectedIndex].text;
}
oTextbox.focus();
showDiv1(false);
}
//通过Enter键确定选项
function getSuggestText2(oListbox,sTextboxId,oEvent){
if(oEvent.keyCode==13){
getSuggestText(oListbox,sTextboxId);
}
}
</script>
</head>
<body>
<p>请输入一个城市的名字:</p>
<p>
<input type="text" id="txt1" value="" size="27"
onkeyup="addSuggestOptions(this,arrCities,'sel1',event)" /><br />
<div id="div1" style="background-color:white;display:none;">
<select id="sel1" style="width:202px" size="6"
onclick="getSuggestText(this,'txt1')" onkeyup="getSuggestText2(this,'txt1',event)">
</select>
</div>
</p>
</body>
</html>
用到的东西都比较基础,当然有很多细节性的东西需要注意。比如说用户选择完一个选项,要注意把组合列表框隐藏。所以这里把组合列表框放在了一个层上,隐藏和显示控制起来就方便一点。
--js中innerHTML,innerText,outerHTML的用法和区别
用法:
<div id="test">
<span style="color:red">test1</span> test2
</div><div id="test">
<span style="color:red">test1</span> test2
</div>
在JS中可以使用:
test.innerHTML: 也就是从对象的起始位置到终止位置的全部内容,包括Html标签。
上例中的test.innerHTML的值也就是
<span style="color:red">test1</span> test2<span style="color:red">test1</span> test2
test.innerText: 从起始位置到终止位置的内容, 但它去除Html标签
上例中的text.innerTest的值也就是“test1 test2”, 其中span标签去除了。
test.outerHTML: 除了包含innerHTML的全部内容外, 还包含对象标签本身。
上例中的text.outerHTML的值也就是
<div id="test"><span style="color:red">test1</span> test2</div><div id="test"><span style="color:red">test1</span> test2</div>
完整示例:
<div id="test">
<span style="color:red">test1</span> test2
</div>
<a href="javascript:alert(test.innerHTML)">innerHTML内容</a>
<a href="javascript:alert(test.innerText)">inerHTML内容</a>
<a href="javascript:alert(test.outerHTML)">outerHTML内容</a><div id="test">
<span style="color:red">test1</span> test2
</div>
<a href="javascript:alert(test.innerHTML)">innerHTML内容</a>
<a href="javascript:alert(test.innerText)">inerHTML内容</a>
<a href="javascript:alert(test.outerHTML)">outerHTML内容</a>
特别说明:
innerHTML是符合W3C标准的属性,而innerText只适用于IE浏览器,因此,尽可能地去使用innerHTML,而少用innerText,如果要输出不含HTML标签的内容,可以使用innerHTML取得包含HTML标签的内容后,再用正则表达式去除HTML标签,下面是一个简单的符合W3C标准的示例:
<div id="test">
<span style="color:red">test1</span> test2
</div>
<a href="javascript:alert(document.getElementById('test').innerHTML.replace(/<.+?>/gim,''))">无HTML,符合W3C标准</a>
--Javascript长文章分页
本例中实现用Javascript 长文章分页,Javascript 分页
<html>
<head>
<style type="text/css">
<!--
#jiax{
width:80%;/*调整显示区的宽*/
height:200px;/*调整显示区的高*/
font-size:14px;
line-height:180%;
border:1px solid #000000;
overflow-x:hidden;
overflow-y:hidden;
word-break:break-all;
}
a{
font-size:12px;
color:#000000;
text-decoration:underline;
}
a:hover{
font-size:12px;
color:#CC0000;
text-decoration:underline;
}
//-->
</style>
</head>
<body>
<div id="jiax">
本届都灵冬奥会,-------------------------------------------上届冬奥会,他们依然以13金傲视群雄。
</div>
<P>
<div id="pages" style="font-size:12px;"></div>
<script language="javascript">
<!--
var obj = document.getElementById("jiax");
var pages = document.getElementById("pages");
window.onload = function(){
var allpages = Math.ceil(parseInt(obj.scrollHeight)/parseInt(obj.offsetHeight));
pages.innerHTML = "<b>共"+allpages+"页</b>";
for (var i=1;i<=allpages;i++){
pages.innerHTML += "<a href=""javascript:showpart('"+i+"');"">第"+i+"页</a> ";
}
}
function showpart(x){
obj.scrollTop=(x-1)*parseInt(obj.offsetHeight);
}
//-->
</script>
</body>
</html>
--用js实现select对div的隐藏与显示
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head>
<body>
<script type="text/javascript">
function change(a){
var xxx = document.getElementById("xxx");
var divArray = xxx.getElementsByTagName("div");
for (var i=0;i<divArray.length;i++) {
if (divArray[i].id == a) {
divArray[i].style.display='';
}else {
divArray[i].style.display='none';
}
}
}
</script>
<div id=xxx>
<div id=aaa>
<h1>aa</h1>
aaaa
</div>
<div id=bbb style="display:none ">
bbbb
</div>
<div id=ccc style="display:none ">
cccc
</div>
</div>
<select onChange="change(this.value)">
<option value="aaa">aaa</option>
<option value="bbb">bbb</option>
<option value="ccc">ccc</option>
</select>
</body>
</html>
---++日期减去天数等于第二个日期
<script language=Javascript>
function cc(dd,dadd)
{
//可以加上错误处理
var a = new Date(dd)
a = a.valueOf()
a = a - dadd * 24 * 60 * 60 * 1000
a = new Date(a)
alert(a.getFullYear() + "年" + (a.getMonth() + 1) + "月" + a.getDate() + "日")
}
cc("12/23/2002",2)
</script>
++++检查一段字符串是否全由数字组成
<script language="Javascript"><!--
function checkNum(str){return str.match(//D/)==null}
alert(checkNum("1232142141"))
alert(checkNum("123214214a1"))
// --></script>
+++++++++++++
--用js处理输出分页(完美版)
head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style type="text/css">
<!--
div{font-size:14px;}
-->
</style>
</head>
<body>
<textarea name="" cols="" rows="" id="conpage" style="display:none;">
<!--pages-->
你好
<!--pages-->
我好
<!--pages-->
他也好
<!--pages-->
全都好
<!--pages-->
</textarea>
<script language="javascript">
var zhenze = /[^0-9]/;//创建正则,表明非数字字符串
var thispage = document.getElementById("conpage").value;//取得内容
var page_amount,x;
page_amount = thispage.split('<!--pages-->').length;
page_amount--;//内容里的pages个数
var asarray = new Array();//数组
var v=0;
for(var t=0;t<page_amount;t++){
asarray[t] = thispage.indexOf("<!--pages-->",v);//记录每个pages的位置
v=asarray[t];
v++;
};
page_amount--;
for(var s=0;s<page_amount;s++){
//以下是分段写出所有内容
document.write('<div id="pg'+(s+1)+'" style="block">');
document.write(thispage.substring(asarray[s],asarray[s+1]));
document.write('</div>');
alert(s+1);
};
var obj,objt;
var s_a_d = 1;//记录当前显示的页数id,默认为第1页显示,当设用showpage时,此变量用于记录上次所显示的页码,
function hidpage(hidt){//此函数用于隐藏页数
obj=eval("document.getElementById('pg"+hidt+"')");
obj.style.display = "none";
};
function showpage(sow){//此函数用于显示页数
obj = eval("document.getElementById('pg"+sow+"')");
objt = eval("document.getElementById('pg"+(s_a_d)+"')");//此句是取得上次显示的页码
objt.style.display = "none";//先隐藏上次显示的页码
obj.style.display = "block";//再显示当前用户需要显示的页码
s_a_d = sow;
document.getElementById("pageamo").value = sow;
alert("当前显示第"+s_a_d+"页");
};
var tts;
function goto(){ //页面转向函数,作用是用户在文本框里输入页码然后转向
tts = document.getElementById("inputpage").value;
if(!tts.match(zhenze)==""){
alert("错误,你输入了非数字类型字符");
return;
};
if(tts>page_amount || tts < 1){
alert("无此页");//非法输入全部检验完毕
}else{
showpage(tts);//合法的执行转向
};
};
document.write('<div>');
document.write('你现在在第<input type="button" id="pageamo" value="'+s_a_d+'" style="font-size:12px;height:18px;background-color:#FFFFFF; color:red;font-weight:bold;border:#FFFFFF 0px solid;">页 ');//标示当前页码
document.write('共有'+page_amount+'页');//总页数
for(var k=0;k<page_amount;k++){
document.write(' <a href="javascript:showpage('+(k+1)+')" style="text-decoration:none;">');
document.write(" ["+(k+1)+"] ");
document.write('</a> ');
hidpage(k+1);//隐藏所有页数
};//for写出页码 : 1 2 3 4 5 ....
showpage(1);//首先显示第一页内容
document.write(' 转到第 <input type="text" id="inputpage" style="width:20px;font-size:12px;height:18px;" value=""> 页');//转向表单
document.write('<input type="button" value=" Go " onclick="goto()" style="height:20px;">');
document.write('</div>');
</script>
</body>
</html>
posted @
2008-02-22 22:13 Sun River|
编辑 收藏
Javascript Table filter
This is a simple but powerful javascript to filter a standard html table. The user enters a term in a text field and just the table entries which contain it will be shown.
function filter (term, _id, cellNr){
var suche = term.value.toLowerCase();
var table = document.getElementById(_id);
var ele;
for (var r = 1; r < table.rows.length; r++){
ele = table.rows[r].cells[cellNr].innerHTML.replace(/<[^>]+>/g,"");
if (ele.toLowerCase().indexOf(suche)>=0 )
table.rows[r].style.display = '';
else table.rows[r].style.display = 'none';
}
}
This function searches in the table with the id defined by _id in every row in the cell defined by cellNr. The search is case insensitive.
The usage is straightforward:
<form>
<input name="filter" onkeyup="filter(this, 'sf', 1)" type="text">
</form>
It should work with all modern browsers, e.g. IE5, Firefox 1.0, Opera 7 and Mozilla 1.0.
Since many people have asked for another version of the script which
- searches in every cell of a row
- searches for more than one keyword (using AND)
I have made another version of the script:
function filter2 (phrase, _id){
var words = phrase.value.toLowerCase().split(" ");
var table = document.getElementById(_id);
var ele;
for (var r = 1; r < table.rows.length; r++){
ele = table.rows[r].innerHTML.replace(/<[^>]+>/g,"");
var displayStyle = 'none';
for (var i = 0; i < words.length; i++) {
if (ele.toLowerCase().indexOf(words[i])>=0)
displayStyle = '';
else {
displayStyle = 'none';
break;
}
}
table.rows[r].style.display = displayStyle;
}
}
Web designers must always keep usability in mind when designing web sites. A site must allow quick and easy access to information during the very short time that a site first holds a visitor's interest. Any confusion that ensues about where things are, and that person's business is gone. Providing a way to precisely search for what they need is an excellent way to provide that usability. What Chris Root explains in this article is a way for your visitors to find and select items contained in long lists. He will also suggest ways to expand this to searching within HTML or XML documents.
Auto-Complete
Many desktop applications have user interface controls that allow a user to find matches for things as they type. This feature can be very useful for long lists of items such as states, countries, streets or product categories. Many web browsers implement this sort of functionality in their address bars. As you type, web site address matches that are part of a list of recently visited sites appear in a menu below the address bar. This reduces the amount of time it takes to access information.
Another place this is implemented is in HTML select menus. Unfortunately this only works with the first letter typed, it is not implemented in all browsers on all platforms and it doesn't shorten the list of choices to only matches.
The script described in this article will allow a user to begin typing what they are looking for in a text box while a select menu updates itself with matches. In the example the list comes from the contents of the select menu but it can also come from other sources.
The HTML
The HTML for this project is pretty simple. You could however use this script several places in a large form with multiple lists of information with no trouble. This example uses a list of city streets.
<body onLoad="fillit(sel,entry)">
<div>Enter the first three letters of a street and select a match from the menu.</div>
<form><label>
Street
<input type="text" name="Street" id="entry" onKeyUp="findIt(sel,this)"><br>
<select id="sel">
<option value="s0001">Adams</option>
<option value="s0002">Alder</option>
<option value="s0003">Banner</option>
<option value="s0004">Birchtree</option>
<option value="s0005">Brook</option>
<option value="s0007">Cooper</option>
<!--and so on and so forth-->
</select></label>
</form>
</body>
</html>
When the text box registers a keyUp event, the find() function calls and passes two parameters, the id of the select menu and a reference to the text field.
For something like state information, allow the user the choice of using the auto-complete script or just selecting something from the menu, especially if they know the item they wish to select is at the top of the list. If someone lives in Alabama for instance, there is no need to have them enter the first three letters of their state when the item they want is at the top of the list of states. Fill the select menu (a list box can be used as well) with all the values and text labels that you want your user to choose from in the HTML code to start with.
Alternatively, depending on the information in the list, the choice may not be as obvious. In this case you could store it in an array only and the user would always need to select a match. If there was only one match, and that match was the correct one, they could leave the menu alone. Otherwise they would need to select from the available matches displayed in the menu.
The longer the list the more useful our script becomes. It has been tested with a list over 1000 city streets and had an acceptable performance, even on a not so modern machine. There is a minimum of two characters before a search will start. this helps reduce the number of matches shown after any given keystroke. This limit can be adjusted easily.
When the page loads, a function called fillit() is called.
//initialize some global variables
var list = null;;
function fillit(sel,fld)
{
var field = document.getElementByid(fld);
var selobj = document.getElementById(sel);
if(!list)
{
ar len = selobj.options.length;
field.value = "";
list = new Array();
for(var i = 0;i < len;i++)
{
list[i] = new Object();
list[i]["text"] = selobj.options[i].text;
list[i]["value"] = selobj.options[i].value;
}
}
else
{
var op = document.createElement("option");
var tmp = null;
for(var i = 0;i < list.length;i++)
{
tmp = op.cloneNode(true);
tmp.appendChild(document.createTextNode(list[i]["text"]));
tmp.setAttribute("value",list[i]["value"]);
selobj.appendChild(tmp)/*;*/
}
}
}
A global variable is initialized to null. This will hold an array that in turn holds two custom objects to hold our data. We then get a reference to our select menu and text field objects. If our array does not exist yet (the page has just loaded so it’s still null), then we get the number of options in our select menu, set the contents of the text field to empty and begin looping through the menu contents.
As we run through each menu option, an object is created that will hold both what is in the value attribute and the text of the option tag.
If however our list array already exists, we are calling the function in order to refill the menu with all the original data. An option element is created and a temporary container is initialized.
In the loop the select menu is reconstructed using DOM methods.
Finding a Match
The findIt() function does the searching. It accepts two arguments. The first is the name of the select menu, the second is the name of the text field.
function findit(sel,field)
{
var selobj = document.getElementById(sel);
var d = document.getElementById("display");
var len = list.length;
if(field.value.length > 2)
{
if(!list)
{
fillit(sel,field);
}
var op = document.createElement("option");
selobj.options.length = 1
var reg = new RegExp(field.value,"i");
var tmp = null;
var count = 0;
var msg = "";
for(var i = 0;i < len;i++)
{
if(reg.test(list[i].text))
{
d.childNodes[0].nodeValue = msg;
tmp = op.cloneNode(true);
tmp.setAttribute("value",list[i].value);
tmp.appendChild(document.createTextNode(list[i].text));
selobj.appendChild(tmp);
}
}
}
else if(list && len > selobj.options.length)
{
selobj.selectedIndex = 0;
fillit(sel,field);
}
}
The first step is to get references to the select menu and the text field. We also need the length of the list array.
If the number of characters in the text field is greater than 2 and the list array exists. Then the menu is cleared of it's content to prepare it for display of any matches. The number of options is set to one rather than 0 to allow for an option that is always there such as a “Select a Street” option.
A regular expression object is then created that will be used to look for a match at the beginning of a given string. Using this object to create a regular expression allows the use of a string from whatever source we wish to be used along with any regular expression characters. The first parameter in the object constructor is the regular expression the second is any flags such as "i" for making the search case insensitive. If you were searching something other than one or two word street names, state names or country names you would want to match the beginning of word boundaries using ""b" instead of "^".
A few utility variables are initialized and we then loop through each of the list items contained in the arrays. If there is a match, the values are used to fill a new copy of the option element we created before the loop started. One thing to note about setting the properties of option elements is that the text label of an option is not an attribute. You must use the optionelement.text syntax rather than setAttribute to set the text label for each option.
If the length of the text in the field is less than 2 characters then we need to determine if the list needs to be refilled with all the values. By doing this, you allow the user to give up on their search before typing more than two characters and manually select something from the menu if they wish. If the user selects the text in the field and clears it to start a new search this will trigger that action. The fillit function is called and the select menu is refilled.
Possible Mods
To make this script and user interface more like the auto-complete widget in a browser address bar, you could use a DHTML menu and provide keyboard control for selecting a match and updating the content in the text box with the selected match.
This script would allow searching in any array of information and with a little modification any HTML collection. Searchable FAQ's, API documentation or help systems could be achieved by searching content contained in a hidden IFrame, the main HTML document itself or an XML document loaded in the background using the HTTPRequest object.
Conclusion
As you can see using auto-complete widgets on a web site can allow a visitor quick access to information. Always be on the lookout for ways to improve the user experience for your visitors and they will continue to come back for more.
posted @
2008-02-22 22:12 Sun River|
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摘要:
9 Javascript(s) you better not miss !!
...
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posted @
2008-02-22 22:10 Sun River|
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http://www.dojoforum.com/taxonomy/term/8
http://www.dojoforum.com/
posted @
2008-02-19 13:50 Sun River|
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from : http://www.demay-fr.net:8080/Wicket-start/app
package wicket.contrib.dojo.examples;
import java.util.ArrayList;
import java.util.Iterator;
import wicket.PageParameters;
import wicket.contrib.dojo.html.list.lazy.DojoLazyLoadingListContainer;
import wicket.contrib.dojo.html.list.lazy.DojoLazyLoadingRefreshingView;
import wicket.extensions.markup.html.repeater.refreshing.Item;
import wicket.markup.html.WebPage;
import wicket.markup.html.basic.Label;
public class LazyTableSample extends WebPage {
public LazyTableSample(PageParameters parameters){
DojoLazyLoadingListContainer container = new DojoLazyLoadingListContainer(this, "container", 3000)
DojoLazyLoadingRefreshingView list = new DojoLazyLoadingRefreshingView(container, "table"){
@Override
public Iterator iterator(int first, int count) {
ArrayList<String> list = new ArrayList<String>();
int i = 0;
while(i < count){
list.add("foo" + (first + i++));
}
//fake a busy and slow machine
int j = 0;
while (j < 1000000000){j++;}
return list.iterator();
}
@Override
protected void populateItem(Item item) {
new Label(item, "label",item.getModel());
}
};
}
}
posted @
2008-02-19 13:45 Sun River|
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摘要:
Dojo API略解续
dojo.lang.string
dojo.string.substituteParams
类似C#中的String.Format函数
%{name}要保...
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posted @
2008-02-19 11:30 Sun River|
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1. How someone can define that a method should be execute inside read-only transaction semantics?
A
|
It is not possible
|
B
|
No special action should be taken, default transaction semantics is read-only
|
C
|
It is possible using the following snippet:
<tx:methodname="some-method"semantics="read-only"/>
|
D
|
It is possible using the following snippet:
<tx:methodname="some-method"read-only="true"/>
|
explanation
Default semantics in Spring is read/write, and someone should use read-only attribute to define read-only semantics for the method.
|
2. What is the correct way to execute some code inside transaction using programmatic transaction management?
A
|
Extend TransactionTemplate class and put all the code inside execute() method.
|
B
|
Implement class containing business code inside the method. Inject this class into TransactionManager.
|
C
|
Extend TransactionCallback class. Put all the code inside doInTransaction() method. Pass the object of created class as parameter to transactionTemplate.execute() method.
|
D
|
Extend TransactionCallback class. Put all the code inside doInTransaction() method. Create the instance of TransactionCallback, call transactionCallback.doInTransaction method and pass TransactionManager as a parameter.
|
3. Select all statements that are correct.
Spring provides a consistent programming model across different transaction APIs such as JTA, JDBC, Hibernate, JPA, and JDO.
|
The Spring Framework supports declarative transaction management.
|
Spring provides a simpler API for programmatic transaction management than a number of complex transaction APIs such as JTA.
|
The transaction management integrates very well with Spring's various data access abstractions.
|
4. Does this method guarantee that all of its invocations will process data with ISOLATION_SERIALIZABLE
?
Assume txManager
to be valid and only existing PlatformTransactionManager
.
publicvoid query(){
DefaultTransactionDefinition txDef =newDefaultTransactionDefinition();
txDef.setIsolationLevel(TransactionDefinition.ISOLATION_SERIALIZABLE);
txDef.setReadOnly(true);
txDef.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
TransactionStatus txStat = txManager.getTransaction(txDef);
// ...
txManager.commit(txStat);
}
explanation
|
If this method executes within an existing transaction context, it's isolation level will reflect the existing isolation level. For example JDBC does not specify what happens when one tries to change isolation level during existing transaction. PROPAGATION_REQUIRES_NEW will assure that transaction isolation is set to serializable.
|
5. You would like to implement class with programmatic transaction management.
How can you get TransactionTemplate instance?
It is necessary to implement a certain interface in this class and then use getTransactionTemplate() call.
|
|
It is possible to declare TransactionTemplate object in configuration file and inject it in this class.
|
It is possible to declare PlatformTransactionManager object in configuration file, inject the manager in this class and then create TransactionTemplate like
TransactionTemplate transactionTemplate =newTransactionTemplate(platformTransactionManager);
|
It's possible to inject either PlatformTransactionManager or TransactionTemplate in this class.
Option one is obviously wrong.
6. Check the correct default values for the @Transactional annotation.
PROPAGATION_REQUIRED
|
The isolation level defaults to the default level of the underlying transaction system.
|
readOnly="true"
|
|
Only the Runtime Exceptions will trigger rollback.
|
The transaction timeout defaults to the default timeout of the underlying transaction system, or none if timeouts are not supported.
|
7. To make a method transactional in a concrete class it's enough to use @Transactional annotation before the method name (in Java >=5.0).
correct answer
FALSE
explanation
No, @Transactional annotation only marks a method as transactional. To make it transactional it is necessary to include the <tx:annotation-driven/> element in XML configuration file.
8. The JtaTransactionManager allows us to use distributed transactions. (t)
posted @
2007-12-01 15:20 Sun River|
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现在JDK1.4里终于有了自己的正则表达式API包,JAVA程序员可以免去找第三方提供的正则表达式库的周折了,我们现在就马上来了解一下这个SUN提供的迟来恩物- -对我来说确实如此。
1.简介:
java.util.regex是一个用正则表达式所订制的模式来对字符串进行匹配工作的类库包。
它包括两个类:Pattern和Matcher Pattern 一个Pattern是一个正则表达式经编译后的表现模式。
Matcher 一个Matcher对象是一个状态机器,它依据Pattern对象做为匹配模式对字符串展开匹配检查。
首先一个Pattern实例订制了一个所用语法与PERL的类似的正则表达式经编译后的模式,然后一个Matcher实例在这个给定的Pattern实例的模式控制下进行字符串的匹配工作。
以下我们就分别来看看这两个类:
2.Pattern类:
Pattern的方法如下: static Pattern compile(String regex)
将给定的正则表达式编译并赋予给Pattern类
static Pattern compile(String regex, int flags)
同上,但增加flag参数的指定,可选的flag参数包括:CASE INSENSITIVE,MULTILINE,DOTALL,UNICODE CASE, CANON EQ
int flags()
返回当前Pattern的匹配flag参数.
Matcher matcher(CharSequence input)
生成一个给定命名的Matcher对象
static boolean matches(String regex, CharSequence input)
编译给定的正则表达式并且对输入的字串以该正则表达式为模开展匹配,该方法适合于该正则表达式只会使用一次的情况,也就是只进行一次匹配工作,因为这种情况下并不需要生成一个Matcher实例。
String pattern()
返回该Patter对象所编译的正则表达式。
String[] split(CharSequence input)
将目标字符串按照Pattern里所包含的正则表达式为模进行分割。
String[] split(CharSequence input, int limit)
作用同上,增加参数limit目的在于要指定分割的段数,如将limi设为2,那么目标字符串将根据正则表达式分为割为两段。
一个正则表达式,也就是一串有特定意义的字符,必须首先要编译成为一个Pattern类的实例,这个Pattern对象将会使用matcher()方法来 生成一个Matcher实例,接着便可以使用该 Matcher实例以编译的正则表达式为基础对目标字符串进行匹配工作,多个Matcher是可以共用一个Pattern对象的。
现在我们先来看一个简单的例子,再通过分析它来了解怎样生成一个Pattern对象并且编译一个正则表达式,最后根据这个正则表达式将目标字符串进行分割:
import java.util.regex.*;
public class Replacement{
public static void main(String[] args) throws Exception {
// 生成一个Pattern,同时编译一个正则表达式
Pattern p = Pattern.compile("[/]+");
//用Pattern的split()方法把字符串按"/"分割
String[] result = p.split(
"Kevin has seen《LEON》seveal times,because it is a good film."
+"/ 凯文已经看过《这个杀手不太冷》几次了,因为它是一部"
+"好电影。/名词:凯文。");
for (int i=0; i
System.out.println(result[i]);
}
}
输出结果为:
Kevin has seen《LEON》seveal times,because it is a good film.
凯文已经看过《这个杀手不太冷》几次了,因为它是一部好电影。
名词:凯文。
很明显,该程序将字符串按"/"进行了分段,我们以下再使用 split(CharSequence input, int limit)方法来指定分段的段数,程序改动为:
tring[] result = p.split("Kevin has seen《LEON》seveal times,because it is a good film./ 凯文已经看过《这个杀手不太冷》几次了,因为它是一部好电影。/名词:凯文。",2);
这里面的参数"2"表明将目标语句分为两段。
输出结果则为:
Kevin has seen《LEON》seveal times,because it is a good film.
凯文已经看过《这个杀手不太冷》几次了,因为它是一部好电影。/名词:凯文。
由上面的例子,我们可以比较出java.util.regex包在构造Pattern对象以及编译指定的正则表达式的实现手法与我们在上一篇中所介绍的 Jakarta-ORO 包在完成同样工作时的差别,Jakarta-ORO 包要先构造一个PatternCompiler类对象接着生成一个Pattern对象,再将正则表达式用该PatternCompiler类的 compile()方法来将所需的正则表达式编译赋予Pattern类:
PatternCompiler orocom=new Perl5Compiler();
Pattern pattern=orocom.compile("REGULAR EXPRESSIONS");
PatternMatcher matcher=new Perl5Matcher();
但是在java.util.regex包里,我们仅需生成一个Pattern类,直接使用它的compile()方法就可以达到同样的效果:
Pattern p = Pattern.compile("[/]+");
因此似乎java.util.regex的构造法比Jakarta-ORO更为简洁并容易理解。
3.Matcher类:
Matcher方法如下: Matcher appendReplacement(StringBuffer sb, String replacement)
将当前匹配子串替换为指定字符串,并且将替换后的子串以及其之前到上次匹配子串之后的字符串段添加到一个StringBuffer对象里。
StringBuffer appendTail(StringBuffer sb)
将最后一次匹配工作后剩余的字符串添加到一个StringBuffer对象里。
int end()
返回当前匹配的子串的最后一个字符在原目标字符串中的索引位置 。
int end(int group)
返回与匹配模式里指定的组相匹配的子串最后一个字符的位置。
boolean find()
尝试在目标字符串里查找下一个匹配子串。
boolean find(int start)
重设Matcher对象,并且尝试在目标字符串里从指定的位置开始查找下一个匹配的子串。
String group()
返回当前查找而获得的与组匹配的所有子串内容
String group(int group)
返回当前查找而获得的与指定的组匹配的子串内容
int groupCount()
返回当前查找所获得的匹配组的数量。
boolean lookingAt()
检测目标字符串是否以匹配的子串起始。
boolean matches()
尝试对整个目标字符展开匹配检测,也就是只有整个目标字符串完全匹配时才返回真值。
Pattern pattern()
返回该Matcher对象的现有匹配模式,也就是对应的Pattern 对象。
String replaceAll(String replacement)
将目标字符串里与既有模式相匹配的子串全部替换为指定的字符串。
String replaceFirst(String replacement)
将目标字符串里第一个与既有模式相匹配的子串替换为指定的字符串。
Matcher reset()
重设该Matcher对象。
Matcher reset(CharSequence input)
重设该Matcher对象并且指定一个新的目标字符串。
int start()
返回当前查找所获子串的开始字符在原目标字符串中的位置。
int start(int group)
返回当前查找所获得的和指定组匹配的子串的第一个字符在原目标字符串中的位置。
(光看方法的解释是不是很不好理解?不要急,待会结合例子就比较容易明白了)
一个Matcher实例是被用来对目标字符串进行基于既有模式(也就是一个给定的Pattern所编译的正则表达式)进行匹配查找的,所有往 Matcher的输入都是通过CharSequence接口提供的,这样做的目的在于可以支持对从多元化的数据源所提供的数据进行匹配工作。
我们分别来看看各方法的使用:
★matches()/lookingAt ()/find():
一个Matcher对象是由一个Pattern对象调用其matcher()方法而生成的,一旦该Matcher对象生成,它就可以进行三种不同的匹配查找操作:
matches()方法尝试对整个目标字符展开匹配检测,也就是只有整个目标字符串完全匹配时才返回真值。
lookingAt ()方法将检测目标字符串是否以匹配的子串起始。
find()方法尝试在目标字符串里查找下一个匹配子串。
以上三个方法都将返回一个布尔值来表明成功与否。
★replaceAll ()/appendReplacement()/appendTail():
Matcher类同时提供了四个将匹配子串替换成指定字符串的方法:
replaceAll()
replaceFirst()
appendReplacement()
appendTail()
replaceAll()与replaceFirst()的用法都比较简单,请看上面方法的解释。我们主要重点了解一下appendReplacement()和appendTail()方法。
appendReplacement(StringBuffer sb, String replacement) 将当前匹配子串替换为指定字符串,并且将替换后的子串以及其之前到上次匹配子串之后的字符串段添加到一个StringBuffer对象里,而 appendTail(StringBuffer sb) 方法则将最后一次匹配工作后剩余的字符串添加到一个StringBuffer对象里。
例如,有字符串fatcatfatcatfat,假设既有正则表达式模式为"cat",第一次匹配后调用appendReplacement(sb, "dog"),那么这时StringBuffer sb的内容为fatdog,也就是fatcat中的cat被替换为dog并且与匹配子串前的内容加到sb里,而第二次匹配后调用 appendReplacement(sb,"dog"),那么sb的内容就变为fatdogfatdog,如果最后再调用一次appendTail (sb),那么sb最终的内容将是fatdogfatdogfat。
还是有点模糊?那么我们来看个简单的程序:
//该例将把句子里的"Kelvin"改为"Kevin"
import java.util.regex.*;
public class MatcherTest{
public static void main(String[] args)
throws Exception {
//生成Pattern对象并且编译一个简单的正则表达式"Kelvin"
Pattern p = Pattern.compile("Kevin");
//用Pattern类的matcher()方法生成一个Matcher对象
Matcher m = p.matcher("Kelvin Li and Kelvin Chan are both working in Kelvin Chens KelvinSoftShop company");
StringBuffer sb = new StringBuffer();
int i=0;
//使用find()方法查找第一个匹配的对象
boolean result = m.find();
//使用循环将句子里所有的kelvin找出并替换再将内容加到sb里
while(result) {
i++;
m.appendReplacement(sb, "Kevin");
System.out.println("第"+i+"次匹配后sb的内容是:"+sb);
//继续查找下一个匹配对象
result = m.find();
}
//最后调用appendTail()方法将最后一次匹配后的剩余字符串加到sb里;
m.appendTail(sb);
System.out.println("调用m.appendTail(sb)后sb的最终内容是:"+ sb.toString());
}
}
最终输出结果为:
第1次匹配后sb的内容是:Kevin
第2次匹配后sb的内容是:Kevin Li and Kevin
第3次匹配后sb的内容是:Kevin Li and Kevin Chan are both working in Kevin
第4次匹配后sb的内容是:Kevin Li and Kevin Chan are both working in Kevin Chens Kevin
调用m.appendTail(sb)后sb的最终内容是:Kevin Li and Kevin Chan are both working in Kevin Chens KevinSoftShop company.
看了上面这个例程是否对appendReplacement(),appendTail()两个方法的使用更清楚呢,如果还是不太肯定最好自己动手写几行代码测试一下。
★group()/group(int group)/groupCount():
该系列方法与我们在上篇介绍的Jakarta-ORO中的MatchResult .group()方法类似(有关Jakarta-ORO请参考上篇的内容),都是要返回与组匹配的子串内容,下面代码将很好解释其用法:
import java.util.regex.*;
public class GroupTest{
public static void main(String[] args)
throws Exception {
Pattern p = Pattern.compile("(ca)(t)");
Matcher m = p.matcher("one cat,two cats in the yard");
StringBuffer sb = new StringBuffer();
boolean result = m.find();
System.out.println("该次查找获得匹配组的数量为:"+m.groupCount());
for(int i=1;i<=m
}
}
输出为:
该次查找获得匹配组的数量为:2
第1组的子串内容为:ca
第2组的子串内容为:t
Matcher对象的其他方法因比较好理解且由于篇幅有限,请读者自己编程验证。
4.一个检验Email地址的小程序:
最后我们来看一个检验Email地址的例程,该程序是用来检验一个输入的EMAIL地址里所包含的字符是否合法,虽然这不是一个完整的EMAIL地址检验程序,它不能检验所有可能出现的情况,但在必要时您可以在其基础上增加所需功能。
import java.util.regex.*;
public class Email {
public static void main(String[] args) throws Exception {
String input = args[0];
//检测输入的EMAIL地址是否以 非法符号"."或"@"作为起始字符
Pattern p = Pattern.compile("^.|^@");
Matcher m = p.matcher(input);
if (m
//检测是否以"www."为起始
p = Pattern.compile("^www.");
m = p.matcher(input);
if (m
//检测是否包含非法字符
p = Pattern.compile("[^A-Za-z0-9.@_-~#]+");
m = p.matcher(input);
StringBuffer sb = new StringBuffer();
boolean result = m.find();
boolean deletedIllegalChars = false;
while(result) {
//如果找到了非法字符那么就设下标记
deletedIllegalChars = true;
//如果里面包含非法字符如冒号双引号等,那么就把他们消去,加到SB里面
m.appendReplacement(sb, "");
result = m.find();
}
m.appendTail(sb);
input = sb.toString();
if (deletedIllegalChars) {
System.out.println("输入的EMAIL地址里包含有冒号、逗号等非法字符,请修改");
System.out.println("您现在的输入为: "+args[0]);
System.out.println("修改后合法的地址应类似: "+input);
}
}
}
例如,我们在命令行输入:java Email www.kevin@163.net
那么输出结果将会是:EMAIL地址不能以www.起始
如果输入的EMAIL为@kevin@163.net
则输出为:EMAIL地址不能以.或@作为起始字符
当输入为:cgjmail#$%@163.net
那么输出就是:
输入的EMAIL地址里包含有冒号、逗号等非法字符,请修改
您现在的输入为: cgjmail#$%@163.net
修改后合法的地址应类似: cgjmail@163.net
5.总结:
本文介绍了jdk1.4.0-beta3里正则表达式库--java.util.regex中的类以及其方法,如果结合与上一篇中所介绍的Jakarta -ORO API作比较,读者会更容易掌握该API的使用,当然该库的性能将在未来的日子里不断扩展,希望获得最新信息的读者最好到及时到SUN的网站去了解。
6.结束语:
本来计划再多写一篇介绍一下需付费的正则表达式库中较具代表性的作品,但觉得既然有了免费且优秀的正则表达式库可以使用,何必还要去找需付费的呢,相信很 多读者也是这么想的:,所以有兴趣了解更多其他的第三方正则表达式库的朋友可以自己到网上查找或者到我在参考资料里提供的网址去看看。
posted @
2007-08-09 12:43 Sun River|
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Example One:创建XLS
群众:笑死人了,这还要你教么,别丢人现眼了,用FileOutputStream就可以了,写个文件,扩展名为xls就可以了,哈哈,都懒得看你的,估计又是个水货上来瞎喊,下去,哟货~~
小笔:无聊的人一边去,懒得教你,都没试过,还鸡叫鸡叫,&^%&**(()&%$#$#@#@
HSSFWorkbook wb = new HSSFWorkbook();//构建新的XLS文档对象
FileOutputStream fileOut = new FileOutputStream("workbook.xls");
wb.write(fileOut);//注意,参数是文件输出流对象
fileOut.close();
Example Two:创建Sheet
群众:有点责任心好吧,什么是Sheet?欺负我们啊?
小笔:花300块去参加Office 培训班去,我不负责教预科
HSSFWorkbook wb = new HSSFWorkbook();//创建文档对象
HSSFSheet sheet1 = wb.createSheet("new sheet");//创建Sheet对象,参数为Sheet的标题
HSSFSheet sheet2 = wb.createSheet("second sheet");//同上,注意,同是wb对象,是一个XLS的两个Sheet
FileOutputStream fileOut = new FileOutputStream("workbook.xls");
wb.write(fileOut);
fileOut.close();
Example Three:创建小表格,并为之填上数据
群众:什么是小表格啊?
小笔:你用过Excel吗?人家E哥天天都穿的是网格衬衫~~~~
HSSFWorkbook document = new HSSFWorkbook();//创建XLS文档
HSSFSheet salary = document.createSheet("薪水");//创建Sheet
HSSFRow titleRow = salary.createRow(0);//创建本Sheet的第一行
titleRow.createCell((short) 0).setCellValue("工号");//设置第一行第一列的值
titleRow.createCell((short) 1).setCellValue("薪水");//......
titleRow.createCell((short) 2).setCellValue("金额");//设置第一行第二列的值
File filePath = new File(baseDir+"excel/example/");
if(!filePath.exists())
filePath.mkdirs();
FileOutputStream fileSystem = new FileOutputStream(filePath.getAbsolutePath()+"/Three.xls");
document.write(fileSystem);
fileSystem.close();
Example Four :带自定义样式的数据(eg:Date)
群众:Date!么搞错,我昨天已经插入成功了~
小笔:是么?那我如果要你5/7/06 4:23这样输出你咋搞?
群众:无聊么?能写进去就行了!
小笔:一边凉快去~
HSSFWorkbook document = new HSSFWorkbook();
HSSFSheet sheet = document.createSheet("日期格式");
HSSFRow row = sheet.createRow(0);
HSSFCell secondCell = row.createCell((short) 0);
/**
* 创建表格样式对象
*/
HSSFCellStyle style = document.createCellStyle();
/**
* 定义数据显示格式
*/
style.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy h:mm"));
/**
* setter
*/
secondCell.setCellValue(new Date());
/**
* 设置样式
*/
secondCell.setCellStyle(style);
File filePath = new File(baseDir+"excel/example/");
if(!filePath.exists())
filePath.mkdirs();
FileOutputStream fileSystem = new FileOutputStream(filePath.getAbsolutePath()+"/Four.xls");
document.write(fileSystem);
fileSystem.close();
Example Five:读取XLS文档
File filePath = new File(baseDir+"excel/example/");
if(!filePath.exists())
throw new Exception("没有该文件");
/**
* 创建对XLS进行读取的流对象
*/
POIFSFileSystem reader = new POIFSFileSystem(new FileInputStream(filePath.getAbsolutePath()+"/Three.xls"));
/**
* 从流对象中分离出文档对象
*/
HSSFWorkbook document = new HSSFWorkbook(reader);
/**
* 通过文档对象获取Sheet
*/
HSSFSheet sheet = document.getSheetAt(0);
/**
* 通过Sheet获取指定行对象
*/
HSSFRow row = sheet.getRow(0);
/**
* 通过行、列定位Cell
*/
HSSFCell cell = row.getCell((short) 0);
/**
* 输出表格数据
*/
log.info(cell.getStringCellValue());
至此,使用POI操作Excel的介绍告一段落,POI是一个仍然在不断改善的项目,有很多问题,比如说中文问题,大数据量内存溢出问题等等,但这个Pure Java的库的性能仍然是不容质疑的,是居家旅行必备良品。
而且开源软件有那么一大点好处是,可以根据自己的需要自己去定制。如果大家有中文、性能等问题没解决的,可以跟我索要我已经改好的库。当然,你要自己看原代码,我也不拦你。
posted @
2007-08-09 12:37 Sun River|
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摘要:
如何将JSP中将查询结果导出为Excel,其实可以利用jakarta提供的POI接口将查询结果导出到excel。POI接口是jakarta组织的一个子项目,它包括POIFS,HSSF,HWSF,HPSF,HSLF,目前比较成熟的是HSSF,它是一组操作微软的excel文档的API,现在到达3.0版本,已经能够支持将图片插入到excel里面。java 代码
import ...
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posted @
2007-08-09 12:26 Sun River|
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