AJAX和JSON Web开发前后台交互

工具：myeclipse6.0

环境：支持Struts1.x的Javaweb动态工程

简介：ajax前后台的数据交互实现依赖于XMLHttpRequest对象；

json实现将后台业务逻辑处理过的数据封装送给前台。

实例1：

前台JSP页面--pages/ajax.jsp

<%@ 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%>">
    
	<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">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	
	 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>ajax样例</title>
        <style type="text/css">
        td {width: 100px;}
        </style>
        <script type="text/javascript" src="/ajax/pages/json2.js"></script>
        <script type="text/javascript">
          function getXHR()
          {
              try
              {
                   return new XMLHttpRequest();
              }
              catch(e)
              {
                  try
                  {
                      return new ActiveXObject("Microsoft.XMLHTTP");
                  }
                  catch(e)
                  {
                      return new ActiveXObject("Msxml2.XMLHTTP");
                  }
              }
          }
          
          function getInfo()
          {
              var xhr = getXHR();
              xhr.open("POST", "/ajax/emp.do?method=getInfo", true);
              xhr.onreadystatechange = function() 
              {
                  if (xhr.readyState == 4) 
                  { 
                      var empInfo = JSON.parse(xhr.responseText);
                      document.getElementById("id").value = empInfo.id;
                      document.getElementById("name").value = empInfo.name;
                      document.getElementById("age").value = empInfo.age;
                      document.getElementById("sal").value = empInfo.sal; 
                      document.getElementById("desc").value = empInfo.desc; 
                      var sexRadios = document.getElementsByName("sex");
                      for(var i=0;i<sexRadios.length;i++)
                      {
                          if(sexRadios[i].value == empInfo.sex)
                              sexRadios[i].checked = true;
                      }
                  }
              }
              xhr.send();
          }
        </script>

  </head>
  
  <body>
    <fieldset style="width: 300px">
           <legend>人员信息</legend>
           <table width="100%">
               <tr><td>ID</td><td><input type="text" id="id" /></td></tr>
               <tr><td>姓名</td><td><input type="text" id="name" /></td></tr>
               <tr><td>年龄</td><td><input type="text" id="age" /></td></tr>
               <tr><td>性别</td><td><input type="radio" value="0" name="sex" />男<input type="radio" value="1" name="sex" />女</td></tr>
               <tr><td>薪资</td><td><input type="text" id="sal" /></td></tr>
               <tr><td colspan="2">备注</td></tr>
               <tr><td colspan="2"><textarea rows="5" id="desc" style="width: 100%"></textarea></td></tr>
           </table>
       </fieldset>
       <input type="button" value="获取数据" onclick="getInfo()"/>
  </body>
</html>

配置Struts1.2支持--/ajax/WebRoot/WEB-INF/struts-config.xml：

<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE struts-config PUBLIC
          "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
          "http://struts.apache.org/dtds/struts-config_1_3.dtd">
<struts-config>
    <action-mappings>
        <action type="com.neusoft.ajax.EmpAction" scope="request" parameter="method" path="/emp" />
    </action-mappings>
</struts-config>

后台数据包装后发送到前台处理--/ajax/src/com/neusoft/ajax/EmpAction.java

package com.neusoft.ajax;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.actions.DispatchAction;
import org.json.JSONException;
import org.json.JSONObject;

public class EmpAction extends DispatchAction
{
    public ActionForward getInfo(ActionMapping mapping, ActionForm form, HttpServletRequest request,
            HttpServletResponse response) throws IOException, JSONException
    {
        JSONObject obj = new JSONObject();
        obj.put("id", 1001);
        obj.put("name", "Will");
        obj.put("age", 28);
        obj.put("sex", 0);
        obj.put("sal", 2000);
        obj.put("desc", "some infomation");
        response.getWriter().write(obj.toString());
        return null;
    }
    
    public ActionForward getMsg(ActionMapping mapping, ActionForm form, HttpServletRequest request,
            HttpServletResponse response) throws IOException, JSONException
    {
        response.getWriter().write("Hello,AlvinKing , A message from server");
        return null;
    }
}

实例2：

共用实例1的后台处理类，前台页面--/ajax/WebRoot/pages/ajax1.jsp

<%@ 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%>">
    
	<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">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
		<title>ajax样例</title>
		<style type="text/css">
		</style>
		<script type="text/javascript">
		  function getXHR()
		  {
			  try
			  {
				   return new XMLHttpRequest();
			  }
			  catch(e)
			  {
				  try
				  {
					  return new ActiveXObject("Microsoft.XMLHTTP");
				  }
				  catch(e)
				  {
					  return new ActiveXObject("Msxml2.XMLHTTP");
				  }
			  }
		  }
		  
		  function getMsg()
		  {
			  var xhr = getXHR();
			  xhr.open("POST", "/ajax/emp.do?method=getMsg", true);
			  xhr.onreadystatechange = function() 
			  {
				  if (xhr.readyState == 4) 
				  { 
					  document.getElementById("msg").value = xhr.responseText;
				  }
			  }
			  xhr.send();
		  }
		</script>
		
		

  </head>
  
  <body>
     <textarea rows="5" cols="100" id="msg"></textarea>
	   <input type="button" value="获取数据" onclick="getMsg()"/>
  </body>
</html>

最后配置工程启动xml，--/ajax/WebRoot/WEB-INF/web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>

  <!DOCTYPE web-app PUBLIC
	"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
	"http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>
  <display-name>ajax</display-name>
  
  <!-- Standard Action Servlet Configuration -->
  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <load-on-startup>2</load-on-startup>
 </servlet>


  <!-- Standard Action Servlet Mapping -->
  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>


  <!-- The Usual Welcome File List -->
  <welcome-file-list>
    <welcome-file>pages/ajax.jsp</welcome-file>
  </welcome-file-list>

</web-app>

AJAX和JSON Web开发前后台交互

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