jquery $.post()的用法 传递json文本 客户端和服务器端相互传递

index.html:
<!DOCTYPE title PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<script type="text/javascript" src="jquery-1.3.2.min.js"></script>
<script type="text/javascript">
function submitForm(){
try{
var params={
username:$("#username").val(),
password:$("#password").val()
};
var url=$("#loginForm").attr("action");
$.post(url,params,function(data){
alert(data);//后台的abc传过来了
},"json");
}catch(e){
alert(e);
return false;
}
}
</script>
<form id="loginForm" action="login!doLogin.action" method="post">
<input type="text" id="username">
<input type="text" id="password">
<input type="button" onclick="submitForm()" value="提交">
</form>
----
LoginAction.java:
package com.cpic.action;
import javax.servlet.http.HttpServletRequest;