function Ajax() {
	this.url="";
	this.postStr="";
	this.handler="";
	
	if(typeof Ajax.initilize=="undefined") {
		Ajax.prototype.get = function() {
			var handler = this.handler;
			var http_request = false;
			if (window.XMLHttpRequest) { // Mozilla, Safari,...
				http_request = new XMLHttpRequest();
			} 
			else if (window.ActiveXObject) { // IE
				try {
					http_request = new ActiveXObject("Msxml2.XMLHTTP");
				} 
				catch (e) {
					try {
					  http_request = new ActiveXObject("Microsoft.XMLHTTP");
					} 
					catch (e) {}
				}
			}
			if (!http_request) {
				alert('Giving up :( Cannot create an XMLHTTP instance');
				return false;
			}
			// 定義事件處理函數為 alterContents()
			http_request.onreadystatechange = function() { 
				if (http_request.readyState == 4) {
					if (http_request.status == 200) {
						var result = http_request.responseText;
						handler(result);
					} 
					else {
						alert('There was a problem with the request.');
					}
				}
			}
			http_request.open('GET', this.url, true);
			http_request.send(null);
		}
	}
	
	if(typeof Ajax.initilize=="undefined") {
		Ajax.prototype.post = function() {
			var handler = this.handler;
			var http_request = false;
			if(window.XMLHttpRequest) { //Mozilla
				http_request = new XMLHttpRequest();
				if (http_request.overrideMimeType) {//set MiME
					http_request.overrideMimeType("text/xml");
				}
			}
			else if (window.ActiveXObject) { //IE
				try {
					http_request = new ActiveXObject("Msxml2.XMLHTTP");
				} catch (e) {
					try {
						http_request = new ActiveXObject("Microsoft.XMLHTTP");
					} catch (e) {}
				}
			}
			if (!http_request) {
				window.alert('Giving up :( Cannot create an XMLHTTP instance');
				return false;
			}
			http_request.open("POST", this.url, true); 
			http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
			http_request.send(this.postStr);
			http_request.onreadystatechange = function() { 
				if (http_request.readyState == 4 && http_request.status == 200) { 
					var result = http_request.responseText;
					handler(result);
				}
			}
		}
	}
	
	Ajax.initilize=true;
}