Ajax的post方法的使用

刚开始学Ajax，看到很多网上的代码都用Get方法提交参数，Tomcat默认ISO编码实在是让人头痛，对付乱码我都是用过滤器做字符编码过滤的，Get方法过滤器监听不到，所以我一直喜欢使用Post方法，下面对Ajax Get和Post方法做一对比

GET:

	var xmlHttpRequest;
	function createXMLHttpRequest(){
		try
	    {
	   // Firefox, Opera 8.0+, Safari
	    xmlHttpRequest=new XMLHttpRequest();
	    }
	 catch (e)
	    {

	  // Internet Explorer
	   try
	      {
		   xmlHttpRequest=new ActiveXObject("Msxml2.XMLHTTP");
	      }
	   catch (e)
	      {

	      try
	         {
	    	  xmlHttpRequest=new ActiveXObject("Microsoft.XMLHTTP");
	         }
	      catch (e)
	         {
	         alert("您的浏览器不支持AJAX！");
	         return false;
	         }
	      }
	    }

	}
	//发送请求函数
	function sendRequestPost(url,param){
		createXMLHttpRequest();
		xmlHttpRequest.open("GET",url+"?"+param,true);
		xmlHttpRequest.onreadystatechange = processResponse;
	}
	//处理返回信息函数
	function processResponse(){
		if(xmlHttpRequest.readyState == 4){
			if(xmlHttpRequest.status == 200){
				var res = xmlHttpRequest.responseText;
				window.alert(res);
			}else{
				window.alert("请求页面异常");
			}
		}
	}
	//身份验证函数
	function userCheck(){
		var userName = document.loginForm.username.value;
		var psw = document.loginForm.password.value;
		if(userName == ""){
			window.alert("用户名不能为空");
			document.loginForm.username.focus();
			return false;
		}
		else{
			var url = "Servlet/userLogin_do";
			var param = "userName="+userName+"&psw="+psw;
			sendRequestPost(url,param);
		}
	}

POST:

	var xmlHttpRequest;
	function createXMLHttpRequest(){
		try
	    {
	   // Firefox, Opera 8.0+, Safari
	    xmlHttpRequest=new XMLHttpRequest();
	    }
	 catch (e)
	    {

	  // Internet Explorer
	   try
	      {
		   xmlHttpRequest=new ActiveXObject("Msxml2.XMLHTTP");
	      }
	   catch (e)
	      {

	      try
	         {
	    	  xmlHttpRequest=new ActiveXObject("Microsoft.XMLHTTP");
	         }
	      catch (e)
	         {
	         alert("您的浏览器不支持AJAX！");
	         return false;
	         }
	      }
	    }

	}
	//发送请求函数
	function sendRequestPost(url,param){
		createXMLHttpRequest();
		xmlHttpRequest.open("POST",url,true);
		xmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
		xmlHttpRequest.onreadystatechange = processResponse;
		xmlHttpRequest.send(param);
	}
	//处理返回信息函数
	function processResponse(){
		if(xmlHttpRequest.readyState == 4){
			if(xmlHttpRequest.status == 200){
				var res = xmlHttpRequest.responseText;
				window.alert(res);
			}else{
				window.alert("请求页面异常");
			}
		}
	}
	//身份验证函数
	function userCheck(){
		var userName = document.loginForm.username.value;
		var psw = document.loginForm.password.value;
		if(userName == ""){
			window.alert("用户名不能为空");
			document.loginForm.username.focus();
			return false;
		}
		else{
			//var url = "Servlet/userLogin_do?userName="+userName+"&psw="+psw;
			var url = "Servlet/userLogin_do";
			var param = "userName="+userName+"&psw="+psw;
			sendRequestPost(url,param);
		}
	}