javascript-ajax-json-java-servlet互相传值取值的学习心得
前几天突然想学习以下jquery easyui 但是里面涉及到了json的知识，于是恶补起来ajax知识，经过以上的查资料，终于弄清楚javascript-ajax-json-java-servlet互相传值取值,的过程，特此分享出来，希望能帮助到初学的朋友么，也为了日后自己查询是使用，好了闲话少说，看下面代码go！！
使用tomcat6.0
index.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%>">
<title>My JSP 'index.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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript" src="jquery-easyui-1.2.3/json.js"></script>
<script type="text/javascript">
//创建XMLHttpRequeset对象，这个对象是ajax的核心对象
function createXMLHttp(){
var xmlhttp;
try{
xmlhttp=new XMLHttpRequest();
}catch(e) {
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
return xmlhttp;
}
//使用Ajax
function ajaxSubmit(){
var xmlhttp=createXMLHttp();
xmlhttp.onreadystatechange=function(){
if(4==xmlhttp.readyState){
if(200==xmlhttp.status){
//获取从服务器端传过来的Text文本
alert(xmlhttp.responseText)
//获取从服务器端传过来的Text文本，并使用JSON的parseJSON函数将文本转换为javascript对象
var myobj = xmlhttp.responseText.parseJSON();
//遍历javascript对象
for (i = 0; i < myobj.programmers.length; i++) {
alert(myobj.programmers[i].lastName);
}
}else {
alert("no");
}
}
}
//使用标准json格式数据，创建javascript对象
var people = { "programmers": [
{ "firstName": "Brett", "lastName":"McLaughlin", "email": "[email protected]" },
{ "firstName": "Jason", "lastName":"Hunter", "email": "[email protected]" },
{ "firstName": "Elliotte", "lastName":"Harold", "email": "[email protected]" }
],
"authors": [
{ "firstName": "Isaac", "lastName": "Asimov", "genre": "science fiction" },
{ "firstName": "Tad", "lastName": "Williams", "genre": "fantasy" },
{ "firstName": "Frank", "lastName": "Peretti", "genre": "christian fiction" }
], "musicians": [
{ "firstName": "Eric", "lastName": "Clapton", "instrument": "guitar" },
{ "firstName": "Sergei", "lastName": "Rachmaninoff", "instrument": "piano" }
]
}
//使用使用JSON的toJSONString函数将javascript对象转换为文本
var value = people.toJSONString();
//象服务器端传文本
xmlhttp.open("post","UserServlet?json="+value,true);
xmlhttp.send(null);
return null;
}
</script>
</head>
<body>
<form action="UserServlet" method="post">
<input type="text" name="username" />
<input type="button" onclick="ajaxSubmit();"value="提交"/>
</form>
</body>
</html>
UserActionServlet.java
package action;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class UserActionServlet extends HttpServlet{
@Override
public void service(HttpServletRequest arg0, HttpServletResponse arg1)
throws ServletException, IOException {
//System.out.println(arg0.getParameter("json"));
PrintWriter writer = arg1.getWriter();
//将从javascript传过来的文本读取到，然后在将文本传回到客户端
writer.print(arg0.getParameter("json"));
writer.flush();
writer.close();
}
}
接下来配置web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>UserServlet</servlet-name>
<servlet-class>action.UserActionServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UserServlet</servlet-name>
<url-pattern>/UserServlet</url-pattern>
</servlet-mapping>
</web-app>