DWR（Direct Web Remoting）是一个用于改善web页面与Java类交互的远程服务器端Ajax开源框架,可以帮助开发人员开发包含AJAX技术的网站.它可以允许在浏览器里的代码使用运行在WEB服务器上的JAVA函数,就像它就在浏览器里一样。
以下模拟一个简单的dwr入门案例，重点理解dwr是如何跟java后台服务器打交道的
模拟效果如下
该功能说明了dwr是怎么跟后台服务器打交道的
模拟从服务器加载下拉列表数据
模拟保存功能
模拟查询功能
接下来为dwr+spring集成步骤：
1、新建一个web工程，导入dwr+spring所需jar，如下图
目录结构图
修改web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app 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">
<!-- Spring上下文 -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:resource/app*.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- 配置DWR前端控制器 -->
<servlet>
<servlet-name>dwrServlet</servlet-name>
<servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
<!-- 指定配置文件 -->
<init-param>
<param-name>config</param-name>
<!-- 如果有多个用","分开 -->
<param-value>
/WEB-INF/classes/config/dwr.xml
</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwrServlet</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
</web-app>
新建实体类Dept
package entity;
public class Dept {
private Long id;
private String name;
public Dept() {
}
public Dept(Long id, String name) {
this.id = id;
this.name = name;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
新建业务逻辑类
DeptServices类
package services;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import entity.Dept;
@SuppressWarnings("unchecked")
public class DeptServices {
public List findDept() {
throw new RuntimeException("查找失败!");
}
public void deleteDept(Long id) {
System.out.println("Delete dept " + id);
}
public List getDeptsForPo() {
List depts = new ArrayList();
depts.add(new Dept(1l, "教质部"));
depts.add(new Dept(2l, "学术部"));
depts.add(new Dept(3l, "就业部"));
depts.add(new Dept(4l, "咨询部"));
return depts;
}
public void saveDept(List<Dept> depts) {
// System.out.println(dept.getId() + ":" + dept.getName());
System.out.println(depts);
}
public List getDepts() {
List depts = new ArrayList();
Map map = new HashMap();
map.put("id", "01");
map.put("name", "教质部");
depts.add(map);
map = new HashMap();
map.put("id", "02");
map.put("name", "学术部");
depts.add(map);
map = new HashMap();
map.put("id", "03");
map.put("name", "就业部");
depts.add(map);
map = new HashMap();
map.put("id", "04");
map.put("name", "咨询部");
depts.add(map);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
return depts;
}
}
HelloServices类
package services;
/**
* @author dlwu
*
*/
public class HelloServices {
public String sayHello(String name){
System.out.println("Hello now!");
return "Hello " + name + "!";
}
}
LoginService类
package services;
import org.directwebremoting.WebContext;
import org.directwebremoting.WebContextFactory;
public class LoginService {
public void checkUserLogin(String userid, String pwd){
WebContext ctx = WebContextFactory.get();
ctx.getSession().setAttribute("userid", userid);
}
public String getLoginUser(){
WebContext ctx = WebContextFactory.get();
return (String)ctx.getSession().getAttribute("userid");
}
}
配置applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
配置系统基础环境
-->
<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-2.0.xsd"
>
<bean id="deptServices" class="services.DeptServices"></bean>
<bean id="loginSrv" class="services.LoginService"></bean>
</beans>
配置dwr.xml,dwr.xml是前台js跟java服务器沟通的桥梁
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://getahead.org/dwr/dwr20.dtd">
<!-- 通用dwr配置 -->
<dwr>
<allow>
<!-- 建立JS对象，将目标对象的方法转换成JS对象的方法 -->
<create javascript="helloSrv" creator="new">
<param name="class" value="services.HelloServices"></param>
</create>
<!-- 从Spring中获取Java对象 -->
<create javascript="deptSrv" creator="spring">
<param name="beanName" value="deptServices"></param>
<!-- 禁止执行 -->
<exclude method="deleteDept" />
</create>
<create javascript="loginSrv" creator="spring">
<param name="beanName" value="loginSrv"></param>
</create>
<!-- 指定针对于特定对象的转换器 -->
<convert match="entity.*" converter="bean"></convert>
<convert match="java.lang.Throwable" converter="bean">
<param name="include" value="message"></param>
</convert>
</allow>
</dwr>
页面
hello.jsp页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'hello.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<!-- 记得引入js，测试地址： http://localhost:8083/dwrweb/dwr/ -->
<script type="text/javascript" src="dwr/engine.js"></script>
<script type="text/javascript" src="dwr/interface/helloSrv.js"></script>
<script type="text/javascript" src="dwr/util.js"></script>
<script type="text/javascript">
function hello(){
//方法一
//返回处理后的结果信息
/*var fn = function(result){
$("msg").innerHTML = result;
}
helloSrv.sayHello($("name").value, fn);*/
//方法二
helloSrv.sayHello($("name").value, function(result){
$("msg").innerHTML=result;
});
//方法三
//使用如下的好处为：不用导入如上三个js
//第一个参数: dwr访问路径，在web.xml中配置，如： <url-pattern>/dwr/*</url-pattern>
//第二个参数: dwr与java服务器通信变量，在dwr.xml中声明
//第三个参数: 服务器方法名
//第四个参数: 页面请求参数，即服务器方法名得参数
//第五个参数: 回调函数
//dwr.engine._execute("dwr", 'helloSrv', 'sayHello', $("name").value, fn);
}
</script>
<body>
<div id="msg"></div>
<input type="text" id="name" />
<input type="button" value="Hello" onclick="hello();" />
</body>
</html>
dept.jsp页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'hello.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<!-- 记得引入js，测试地址： http://localhost:8083/dwrweb/dwr/ -->
<script type="text/javascript" src="dwr/engine.js"></script>
<script type="text/javascript" src="dwr/interface/helloSrv.js"></script>
<script type="text/javascript" src="dwr/util.js"></script>
<script type="text/javascript">
function loadDept(){
//说明已经加载，不必重新加载
if($('depts').options.length > 0){
return;
}
DWRUtil.addOptions('depts', [{id:'',name:'正在下载...'}], 'id', 'name');
dwr.engine._execute("dwr", 'deptSrv', 'getDepts', function(depts){
DWRUtil.removeAllOptions('depts');
DWRUtil.addOptions('depts', depts, 'id', 'name');
});
}
function loadDept2(){
if($('depts2').options.length > 0){
return;
}
DWRUtil.addOptions('depts2', [{id:'',name:'正在下载...'}], 'id', 'name');
dwr.engine._execute("dwr", 'deptSrv', 'getDeptsForPo', function(depts){
DWRUtil.removeAllOptions('depts2');
DWRUtil.addOptions('depts2', depts, 'id', 'name');
});
}
function saveDept(){
//声明dept对象
var dept = {
id:$("deptid").value,
name:$("deptname").value
};
dwr.engine._execute("dwr", 'deptSrv', 'saveDept', [dept], function(){
alert('保存成功!');
});
}
function find(){
dwr.engine._execute("dwr", 'deptSrv', 'findDept', {
callback:function(results){
alert('查询成功!');
},
errorHandler:function(e){
alert("查询失败:" + e);
}
});
}
</script>
<body>
<select id="depts" onclick="loadDept();"></select>
<select id="depts2" onclick="loadDept2();"></select>
<hr/>
ID:<input id="deptid" type="text" size="8"/>
Name:<input id="deptname" type="text" size="8"/>
<input value="保存部门" type="button" onclick="saveDept();"/>
<input value="查找" type="button" onclick="find();"/>
</body>
</html>
访问路径：
测试路径：http://localhost:8083/dwrweb/dwr/