1. 在web.xml文件中注册dwr
<servlet>
<servlet-name>dwr-invoker</servlet-name>
<display-name>DWR Servlet</display-name>
<description>Direct Web Remoter Servlet</description>
<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>
<welcome-file-list>
<welcome-file>search.jsp</welcome-file>
</welcome-file-list>
2.dwr.xml
<dwr>
<allow><convert convert="bean" match="dwr.sample.Apartment"/>
<create>
<creator="new" javascript="ApartmentDAO" class="dwr.sample.ApartmentDAO">
<include method="findApartments"/>
<include method="countApartments"/>
</creator>
</create>
</allow>
</dwr>
3.DB
CREATE TABLE APARTMENTS (id INTEGER, bedrooms INTEGER, bathrooms INTEGER, price INTEGER, address VARCHAR, city VARCHAR, province VARCHAR);
INSERT INTO APARTMENTS VALUES (16001, 1, 1, 850, '123 King St. East', 'Toronto', 'ON');
INSERT INTO APARTMENTS VALUES (16002, 2, 1, 1000, '1023 Yonge Ave.', 'Toronto', 'ON');
INSERT INTO APARTMENTS VALUES (16003, 2, 2, 1050, '27 Winchester St.', 'Toronto', 'ON');
4.Apertment.java
普通的javabean
5.DBUtils.java
数据库链接类
public class DBUtils {
/*
* Creates the sample data (table and records).
*/
public static void setupDatabase(BufferedReader reader) {
Connection c = null;
Statement stmt = null;
try {
c = openConnection();
stmt = c.createStatement();
// reads the file with the SQL statements
String line;
while ((line = reader.readLine()) != null) {
stmt.execute(line);
}
stmt.close();
c.close();
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
stmt.close();
c.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/*
* Opens a database connection.
*/
public static Connection openConnection() throws SQLException {
Connection c = DriverManager.getConnection("jdbc:hsqldb:mem:dwr-sample", "sa", "");
return c;
}
}
6.ContextListener.java
实现了ServletContextListerer接口的类
public class ContextListener implements javax.servlet.ServletContextListener {
/**
* This method is invoked when the Web Application has been removed and is
* no longer able to accept requests.
* @param event
*/
public void contextDestroyed(ServletContextEvent event) {
}
/**
* This method is invoked when the Web Application is ready to service requests.
* @param event
*/
public void contextInitialized(ServletContextEvent event) {
try {
// load the driver
Class.forName("org.hsqldb.jdbcDriver");
// create the table and add sample data
InputStreamReader in = new InputStreamReader(getClass().getClassLoader().getResourceAsStream("db.sql"));
BufferedReader reader = new BufferedReader(in);
DBUtils.setupDatabase(reader);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
7.ApartmentDAO.java
业务逻辑层
public class ApartmentDAO {
/**
* Returns the available apartments based on the search criteria.
* @param bedrooms minimum number of bedrooms
* @param bathrooms minimum number of bathrooms
* @param price maximum price to be paid
* @return
*/
public Collection findApartments(int bedrooms, int bathrooms, int price) {
Collection list = new Vector();
String sql = "select * from APARTMENTS" +
createSearchWhereClause(bedrooms, bathrooms, price) +
"order by bedrooms, bathrooms, price";
// define db variables
Connection c = null;
Statement stmt = null;
try {
c = DBUtils.openConnection();
stmt = c.createStatement();
// just run the sql statement
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()) {
Apartment apartment = this.getApartment(rs);
list.add(apartment);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
stmt.close();
c.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return list;
}
/**
* Returns the number of available apartments based on the search criteria.
* @param bedrooms minimum number of bedrooms
* @param bathrooms minimum number of bathrooms
* @param price maximum price to be paid
* @return
*/
public int countApartments(int bedrooms, int bathrooms, int price) {
String sql = "select count(*) as total from APARTMENTS" + createSearchWhereClause(bedrooms, bathrooms, price);
int numberApartments = -1;
// define db variables
Connection c = null;
Statement stmt = null;
try {
c = DBUtils.openConnection();
stmt = c.createStatement();
// just run the sql statement
ResultSet rs = stmt.executeQuery(sql);
if (rs.next()) {
numberApartments = rs.getInt("total");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
stmt.close();
c.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return numberApartments;
}
/**
* Creates a Unit object from the database.
* @param rs
* @return
* @throws SQLException
*/
private Apartment getApartment(ResultSet rs) throws SQLException {
Apartment ap = new Apartment();
ap.setId(rs.getInt("id"));
ap.setAddress(rs.getString("address"));
ap.setBedrooms(rs.getInt("bedrooms"));
ap.setBathrooms(rs.getInt("bathrooms"));
ap.setPrice(rs.getInt("price"));
ap.setCity(rs.getString("city"));
ap.setProvince(rs.getString("province"));
return ap;
}
/**
* Creates the where clause for the search SQL statement.
* @param bedrooms
* @param bathrooms
* @param price
* @return
*/
private String createSearchWhereClause(int bedrooms, int bathrooms, int price) {
String where = " where bedrooms >= " + bedrooms +
" and bathrooms >= " + bathrooms +
" and price < " + price;
return where;
}
}
8. search.jsp
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>DWR Example</title>
<style type="text/css" media="screen">
@import url( style.css );
</style>
<script src='dwr/interface/ApartmentDAO.js'></script>
<script src='dwr/engine.js'></script>
<script src='dwr/util.js'></script>
<script>
function updateTotal() {
$("resultTable").style.display = 'none';
var bedrooms = document.getElementById("bedrooms").value;
var bathrooms = document.getElementById("bathrooms").value;
var price = document.getElementById("price").value;
ApartmentDAO.countApartments(loadTotal, bedrooms, bathrooms, price);
}
function updateResults() {
DWRUtil.removeAllRows("apartmentsbody");
var bedrooms = document.getElementById("bedrooms").value;
var bathrooms = document.getElementById("bathrooms").value;
var price = document.getElementById("price").value;
ApartmentDAO.findApartments(fillTable, bedrooms, bathrooms, price);
$("resultTable").style.display = '';
}
var getId = function(unit) { return unit.id };
var getAddress = function(unit) { return unit.address };
var getBedrooms = function(unit) { return unit.bedrooms };
var getBathrooms = function(unit) { return unit.bathrooms };
var getPrice = function(unit) { return unit.price };
function loadTotal(data) {
document.getElementById("totalRecords").innerHTML = data;
}
function fillTable(apartment) {
DWRUtil.addRows("apartmentsbody", apartment, [ getId, getAddress, getBedrooms, getBathrooms, getPrice ]);
}
</script>
</head>
<body onload="updateTotal();">
<h2>Find an apartment to rent</h2>
<table border="0">
<form name="rentalForm">
<tr width="400">
<td width="100">City</td>
<td width="300">Toronto</td>
</tr>
<tr>
<td>Beds</td>
<td>
<select id="bedrooms" onchange="updateTotal()">
<option value="1">1 or more</option>
<option value="2">2 or more</option>
<option value="3">3 or more</option>
<option value="4">4 or more</option>
</select>
</td>
</tr>
<tr>
<td>Baths</td>
<td>
<select id="bathrooms" onchange="updateTotal()">
<option value="1">1 or more</option>
<option value="2">2 or more</option>
<option value="3">3 or more</option>
<option value="4">4 or more</option>
</select>
</td>
</tr>
<tr>
<td>Price</td>
<td>
<select id="price" onchange="updateTotal()">
<option value="800">under $800</option>
<option value="1000">under $1,000</option>
<option value="1250">under $1,250</option>
<option value="1500" selected="selected">under $1,500</option>
<option value="1800">under $1,800</option>
<option value="2000">under $2,000</option>
</select>
</td>
</tr>
<tr>
<td colspan="2">
<blockquote>
Available apartments: <span id="totalRecords" style="font-weight:bold;"></span>
</blockquote>
</td>
</tr>
</form>
</table>
<p><input type="button" value="Show results!" onClick="updateResults();"></p>
<div id="resultTable">
<h2>Results</h2>
<table border="1">
<thead>
<tr>
<th width="40">Id</th>
<th width="180">Address</th>
<th width="60">Beds</th>
<th width="60">Baths</th>
<th width="60">Price</th>
</tr>
</thead>
<tbody id="apartmentsbody">
</tbody>
</table>
</div>
</body>
</html>
由于项目需要,需在我们现有的struts、hibernate工程上集成ajax功能.项目组决定使用Dwr.
刚开始研究Dwr.觉得真的很不错, 只需很少量的代码,就能在现有的工程上集成ajax技术. 期待Dwr有更辉煌的明天！
喜欢Dwr技术的IT界朋友可以与本人联系！望提出好的意见与建议.