一个AJAX类

以前写的一个AJAX类，兼容性还不错，简单易用，记下了方便以后找 :)

基本用法：

var ajax = new AjaxObj(url);
 
ajax.addListener(200, function(r){
   alert(r);
});
 
ajax.send();

也可以连续调用：

var ajax = new AjaxObj(url).addListener(200, function(r){
   alert(r);
}).send();

另外还支持自定义的POST或GET方式请求，以及监视不同的HTTP状态码，自己看代码琢磨吧 :)

完整代码：

AjaxObj = function(url, method, content){
	this.r = null;
	this.url = url;
	this.method = method;
	this.content = content;
	this.header = {};
	this.header["Connection"] = "close";
	this.header["Content-type"] = "application/x-www-form-urlencoded";
 
	var self = this;
 
	if(window.XMLHttpRequest){
		this.r = new XMLHttpRequest();
	}else if(window.ActiveXObject){
		try { 
			this.r = new ActiveXObject("Msxml2.XMLHTTP"); 
		} catch(e) {
			try{ 
				this.r = new ActiveXObject("Microsoft.XMLHTTP"); 
			} catch(e) {
			}
		}
	}
 
	this.addListener = function(http_status, func){
		if(!this.L)
			this.L=[];
		this.L[http_status] = func;
		return this;
	};
 
	this.setHeader = function(name, value){
		this.header[name] = value;
		this.r.setRequestHeader(name, value);
		return this;
	};
 
	this.send = function(){
		if(this.method != "post" && this.method != "get")
			this.method = "get";
 
		this.r.open(this.method, this.url, true);
 
		for(var h in this.header) {
			this.r.setRequestHeader(h, this.header[h]);
		}
 
		this.r.send(this.content);
	};
 
	if(this.r) this.r.onreadystatechange = function(){
		if(self.r.readyState == 4 && self.L[self.r.status] != null)
			self.L[self.r.status](self.r.responseText);
	};
};