var http_request = null;
function send_request(url,param,bpost,processFun) {//初始化、指定处理函数、发送请求的函数
	http_request = null;
	//开始初始化XMLHttpRequest对象
	if(window.XMLHttpRequest) { //Mozilla 浏览器
		http_request = new XMLHttpRequest();
		if (http_request.overrideMimeType) {//设置MiME类别
			http_request.overrideMimeType("text/xml");
		}
	}
	else if (window.ActiveXObject) { // IE浏览器
		try {
			http_request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				http_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		}
	}
	if (http_request==null) { // 异常，创建对象实例失败
		window.alert("不能创建XMLHttpRequest对象实例.");
		return false;
	}
	//http_request.onreadystatechange = processRequest;
	if(processFun == undefined)
		processFun = processRequest;
	http_request.onreadystatechange = processFun;
	
	// 确定发送请求的方式和URL以及是否同步执行下段代码	
	http_request.open("POST", url, bpost);
	http_request.setRequestHeader("If-Modified-Since","0");	
    http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=utf-8");
    //http_request.setRequestHeader("content-length",param.length);
	http_request.send(param);
}