使用Hessian开发C/S模式的小系统
之所以叫小系统，主要是因为Hessian不支持Hibernate的延迟加载，所以需要在DAO层使用Hibernate的同学请注意了。
Hessian其实是一种RMI技术，已经被集成在Spring Framework中了，这样就很方便了。
首先看客户端
第一步：
先定义Client与Server交互的接口。
比如：
package edu.zsu.zouang.pos.service;
import edu.zsu.zouang.pos.pojo.User;
/**
* Please Contact <a href="mailto:richardeee@gmail.com">Zou Ang</a>
* @author Zou Ang
*
*/
public interface ILoginService extends Service{
public User login(String loginName, String password);
public boolean logout(String loginName);
}
然后定义xml配置文件
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd" >
<beans>
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>config.properties</value>
</property>
</bean>
<bean id="urlMapping"
class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping">
</bean>
<bean id="loginClient" class="org.springframework.remoting.caucho.HessianProxyFactoryBean">
<property name="serviceUrl">
<value>http://${serverName}:${port}/${contextPath}/login.do</value>
</property>
<property name="serviceInterface">
<value>edu.zsu.zouang.pos.service.ILoginService</value>
</property>
</bean>
</beans>
其中config.properties文件的内容如下：
#在此配置服务器端信息
#服务器地址
serverName=172.18.17.111
#服务器端端口号
port=8080
#服务器端上下文
contextPath=pos
这样，在得到loginClient对象以后，就可以直接使用login(username,pwd)来登录了。Hessian会自动把请求发送给服务器端。
客户端的代码基本就这么多，主要应该关注的是对用户的表现，至于业务逻辑，就让服务器端去实现好了。
再看服务器端的配置：
接口跟上面的ILoginService一样
在我的程序中，使用了Spring MVC进行URL Mapping。
web.xml内容如下：
<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<display-name>pos</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<context-param>
<param-name>webAppRootKey</param-name>
<param-value>pos.root</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
</listener>
<context-param>
<param-name>log4jConfigLocation</param-name>
<param-value>WEB-INF/log4j.properties</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
WEB-INF/springctx-common.xml
WEB-INF/springctx-login.xml
WEB-INF/applicationContext.xml
WEB-INF/DispatcherServlet-servlet.xml
</param-value>
</context-param>
<filter>
<filter-name>hibernateFilter</filter-name>
<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>hibernateFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>DispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>DispatcherServlet</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>dwr-invoker</servlet-name>
<display-name>DWR Servlet</display-name>
<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
</web-app>
其中DispatcherServlet-servlet.xml(注意，名称不能更改）内容如下：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd" >
<beans>
<bean name="/login.do" class="org.springframework.remoting.caucho.HessianServiceExporter">
<property name="service">
<ref bean="loginService" />
</property>
<property name="serviceInterface">
<value>edu.zsu.zouang.pos.service.ILoginService</value>
</property>
</bean><!--
<bean name="/inventory.do" class="org.springframework.remoting.caucho.HessianServiceExporter">
<property name="service">
<ref bean="posGoodsService" />
</property>
<property name="serviceInterface">
<value>edu.zsu.zouang.pos.service.IPosGoodsService</value>
</property>
</bean>
--></beans>
在配置文件中的loginService就是服务器端时间处理登录的对象，它要实现ILoginService接口
在spring-common.xml中定义了数据源和一些基本的类，比如sessionFactory和transactionManager,dataSource使用了C3P0
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd" >
<beans>
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>WEB-INF/connection.properties</value>
</property>
</bean>
<bean id="c3p0DataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
<property name="driverClass" value="${jdbc.driverClassName}" />
<property name="jdbcUrl" value="${jdbc.url}" />
<property name="user" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="minPoolSize" value="${jdbc.minPoolSize}" />
<property name="maxPoolSize" value="${jdbc.maxPoolSize}" />
<property name="maxIdleTime" value="${jdbc.maxIdleTime}" />
<property name="acquireIncrement" value="${jdbc.acquireIncrement}" />
<property name="maxStatements" value="${jdbc.maxStatements}" />
<property name="initialPoolSize" value="${jdbc.initialPoolSize}" />
<property name="idleConnectionTestPeriod" value="${jdbc.idleConnectionTestPeriod}" />
<property name="acquireRetryAttempts" value="${jdbc.acquireRetryAttempts}" />
<property name="breakAfterAcquireFailure" value="${jdbc.breakAfterAcquireFailure}" />
<property name="testConnectionOnCheckout" value="${jdbc.testConnectionOnCheckout}" />
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="mappingResources">
<list>
<value>edu/zsu/zouang/pos/pojo/Goods.hbm.xml</value>
<value>edu/zsu/zouang/pos/pojo/GoodsType.hbm.xml</value>
<value>edu/zsu/zouang/pos/pojo/User.hbm.xml</value>
<value>edu/zsu/zouang/pos/pojo/Role.hbm.xml</value>
<value>edu/zsu/zouang/pos/pojo/UserRole.hbm.xml</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">${hibernate.dialect}</prop>
<prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
</props>
</property>
<property name="dataSource" ref="c3p0DataSource"/>
</bean>
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
</beans>
在applicationContext.xml中配置了Spring MVC所需要的类
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<!--Definition of View Resolver -->
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass"
value="org.springframework.web.servlet.view.JstlView" />
<property name="prefix" value="/WEB-INF/jsp/" />
<property name="suffix" value=".jsp" />
</bean>
<!--Request Mapping -->
<bean id="urlMapping"
class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping">
</bean>
</beans>
经过上面的配置，就实现了最基础的Hessian功能了。这个程序很小，但是可以帮助我们熟悉一下Hessian，等于是个入门吧