/*
AJAX v1.4
HJF 2009-7-5
*/
function AjaxDO(){

this.HttpRequest = null;

this.openMethod = null; //HTTP请求的方法，为Get、Post 或者Head

this.openURL = null; //是目标URL。基于安全考虑，这个URL 只能是同网域的，否则会提示“没有权限”的错误。

this.openAsync = null; //是指定在等待服务器返回信息的时间内是否继续执行下面的代码。如果为False，则不会继续执行，直到服务器返回信息。默认为True。

this.ProcessRequestFunction = function(_HttpRequest) {return;} //处理返回信息的函数入口

this.ProcessRequestParam = null; //处理访问信息时的附加参数

this.LoadingImg = null; //正在载入的图片，一般为.gif动画

//初始化HttpRequest
this.InitHttpRequest = function(){
var http;

// try {
// http = new ActiveXObject("Msxml2.XMLHTTP");
// } catch(e) {
// try {
// http = new ActiveXObject("Microsoft.XMLHTTP");
// } catch(e) {
// http = false;
// }
// }

try {
if(window.ActiveXObject){
for(var i=5; i; i--){
try{
if(i==2){
http = new ActiveXObject("Microsoft.XMLHTTP");
}else{
http = new ActiveXObject( "Msxml2.XMLHTTP." + i + ".0" );
}
break;
}catch(e){
//alert(i);
http = false;
}
}
}else if(window.XMLHttpRequest){
http = new XMLHttpRequest();
if(http.overrideMimeType){
http.overrideMimeType("text/xml");
}
}
}catch(e){
http = false;
}

if(!http){
Alert("不能创建XMLHttpRequest对象实例");
return http;
}

this.HttpRequest = http;
return http;
}

//检测 this.HttpRequest
this.checkHttpRequest = function(){
if(!this.HttpRequest){
return this.InitHttpRequest();
}
return this.HttpRequest;
}

//修改MIME类别
//http.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); //如果要传文件或者Post 内容给服务器
//http.setRequestHeader("Content-Type","text/xml");
//http.setRequestHeader("Content-Type","gb2312");
this.setRequestHeader = function(mime){
if(!this.checkHttpRequest()){
return false;
}
try{
this.HttpRequest.setRequestHeader("Content-Type", mime);
return true;
}catch(e){
if(e instanceof Error){
Alert("修改MIME类别错误");
return false;
}
}
}

//设置状态改变的事件触发器
this.setOnReadyStateChange = function(funHandle, Param){
if(!this.checkHttpRequest()){
return false;
}
this.ProcessRequestFunction = funHandle;
this.ProcessRequestParam = Param;
return true;
}

this.setLoadingImg = function(ImgID){
this.LoadingImg = ImgID;
}

//建立HTTP连接
//open("method","URL"[,asyncFlag[,"userName"[, "password"]]])
this.Open = function(method, url, async, username, psw){
if(!this.checkHttpRequest()){
return false;
}
this.openMethod = method;
this.openURL = url;
this.openAsync = async;
if((this.openMethod==null) || ((this.openMethod.toUpperCase()!="GET")&&(this.openMethod.toUpperCase()!="POST")&&(this.openMethod.toUpperCase()!="HEAD"))){
Alert("请指定HTTP请求的方法，为Get、Post 或者Head");
return false;
}
if((this.openURL==null)||(this.openURL=="")){
Alert("请指定目标URL");
return false;
}
try{
this.HttpRequest.open(this.openMethod, this.openURL, this.openAsync, username, psw);
}catch(e){
if(e instanceof Error){
Alert("无法建立HTTP连接");
return false;
}
}

if(this.openMethod.toUpperCase()=="POST"){
if(!this.setRequestHeader("application/x-www-form-urlencoded")){
Alert("修改MIME类别失败");
return false;
}
}

if(this.openAsync){ //异步模式，程序继续执行
if(this.ProcessRequestFunction==null){
Alert("请指定处理返回信息的函数");
return false;
}
var _http_request_ajax = this.HttpRequest;
var _this_ajax = this;
this.HttpRequest.onreadystatechange = function(){
if(_http_request_ajax.readyState==4) {
if(_http_request_ajax.status==200) {
_this_ajax.ProcessRequestFunction(_http_request_ajax, _this_ajax.ProcessRequestParam, _this_ajax.LoadingImg);
}else{
Alert("您所请求的页面有异常。");
return false;
}
}
}
}

if(this.LoadingImg!=null){
funShow(this.LoadingImg);
}

return true;
}

//向服务器发出HTTP请求
//格式：name=value&anothername=othervalue&so=on
this.Send = function(idata){
if(!this.checkHttpRequest()){
return false;
}
var data = null;
if(this.openMethod.toUpperCase()=="POST"){
data = funEscapeAll(idata);
}
try{
this.HttpRequest.send(data);
return true;
}catch(e){
if(e instanceof Error){
Alert("向服务器发出HTTP请求失败");
return false;
}
}
}

//处理服务器返回的信息
this.getResponseText = function(type){
if(!this.checkHttpRequest()){
return false;
}
if(this.HttpRequest.readyState==4) {
if(this.HttpRequest.status==200) {
if((type!=null) && (type.toUpperCase()=="XML")){
return this.HttpRequest.responseXML;
}
return this.HttpRequest.responseText;
}else{
Alert("您所请求的页面有异常。");
return false;
}
}
}

//停止当前请求
this.abort = function(){
if(!this.checkHttpRequest()){
return false;
}

if(this.LoadingImg!=null){
funHide(this.LoadingImg);
}

if(this.HttpRequest.readyState>0 && this.HttpRequest.readyState<4){
this.HttpRequest.abort();
}
}

}

//=====================================================================================
//公共函数
//=====================================================================================
function $(_obj){
var o;
if (typeof(_obj)!="string")
return _obj;
else{
try{
document.all;
try{
o=document.all(_obj);
}catch(e){
return null;
}
}catch(ee){
try{
o=document.getElementById(_obj);
}catch(e){
return null;
}
}
return o;
}
}

function funEscapeAll(str){
var t = "&";
var s = str.split(t);
if(s.length<=0) return str;
for(var i=0; i<s.length; i++){
s[i] = funEscapeOne(s[i]);
}
return s.join(t);
}

function funEscapeOne(str){
var i = str.indexOf("=");
if(i==-1) return str;
var t = URLEncode(str.substr(i+1));
return str.substring(0, i+1)+t;
}

function URLEncode(str){
return encodeURIComponent(str);
/*
return escape(str).replace(/\+/g, "%2B").
replace(/\"/g,"%22").
replace(/\'/g, "%27").
replace(/\//g,"%2F");
*/
}

function funEscapeXML(content) {
if (content == undefined)
return "";
if (!content.length || !content.charAt)
content = new String(content);
var result = "";
var length = content.length;
for (var i = 0; i < length; i++) {
var ch = content.charAt(i);
switch (ch) {
case '&':
result += "&";
break;
case '<':
result += "<";
break;
case '>':
result += ">";
break;
case '"':
result += """;
break;
case '\'':
result += "'";
break;
default:
result += ch;
}
}
return result;
}

function funShow(_obj){
if(typeof(_obj)=="object")
_obj.style.visibility = "inherit";
else
$(_obj).style.visibility = "inherit";
}

function funHide(_obj){
if(typeof(_obj)=="object")
_obj.style.visibility = "hidden";
else
$(_obj).style.visibility = "hidden";
}

function Alert(str){
alert(str);
//window.status = str;
}

/*

使用例子：

function processRequest(http_request, _val, _loading_img){
if(http_request.responseXML.documentElement){
//alert(decodeURIComponent(http_request.responseXML.documentElement.xml));
}else{
//alert(decodeURIComponent(http_request.responseText));
}
alert(_val);
funHide(_loading_img);
}

1、GET
var ajax = new AjaxDO();

ajax.setLoadingImg(_loading_img);
ajax.setOnReadyStateChange(processRequest, _val);
ajax.Open("GET", url, true); //异步模式，程序继续执行
ajax.Send("");

ajax.Open("GET", url, false); //非异步模式，程序等待
ajax.Send("");
var xml_doc = ajax.getResponseText("XML");
var text_doc = ajax.getResponseText("TEXT");

2、POST
var ajax = new AjaxDO();

ajax.setLoadingImg(_loading_img);
ajax.setOnReadyStateChange(processRequest, _val);
ajax.Open("POST", url, true); //异步模式，程序继续执行
ajax.Send(data);

ajax.Open("POST", url, false); //非异步模式，程序等待
ajax.Send(data);
var xml_doc = ajax.getResponseText("XML");
var text_doc = ajax.getResponseText("TEXT");


注，客户端发送带有中文或HTML脚本的信息时，发送的信息必须调用：encodeURIComponent函数，例如：
var data = encodeURIComponent($('message').value);
实际是调用了两次，Ajax类内部又调用一次。

服务端（Java版）需要做下转码：
String message = request.getParameter("message");
message = URLDecoder.decode(message, "UTF-8");

*/

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>Ajax类</title>
<script src="Ajax.js" src="Ajax.js"></script>

<style type="text/css"><!--
#Layer1 {
position:absolute;
left:670px;
top:11px;
width:15px;
height:15px;
z-index:10000;
background-color:#FF0000;
font-size:13;
border:none;
visibility:hidden;
}
--></style><style type="text/css" bogus="1">#Layer1 {
position:absolute;
left:670px;
top:11px;
width:15px;
height:15px;
z-index:10000;
background-color:#FF0000;
font-size:13;
border:none;
visibility:hidden;
}</style>
</head>

<body>
<div id="Layer1"><img src="indicator_flower.gif" src="indicator_flower.gif" width="15" /></div>
<script type="text/javascript" language="javascript"><!--
function processRequest(http_request, _val, _loading_img){
alert(http_request.responseXML.documentElement.xml);
//alert(http_request.responseText);
funHide(_loading_img);
}
// --></script>
<script type="text/javascript" language="javascript"><!--
var url = "http://www.w3schools.com/xml/simple.xml";
var data = "";

var ajax = new AjaxDO();

function btnAjax1(){
//var ajax = new AjaxDO();
//ajax.InitHttpRequest();
ajax.abort();

ajax.setLoadingImg(document.getElementById("Layer1"));
ajax.setOnReadyStateChange(processRequest);
ajax.Open("GET", url, true); //异步模式，程序继续执行
ajax.Send("");
}

function btnAjax2(){
//var ajax = new AjaxDO();
//ajax.InitHttpRequest();
ajax.abort();

ajax.Open("GET", url, false); //非异步模式，程序等待
ajax.Send("");
alert(ajax.getResponseText("XML").documentElement.xml);
alert(ajax.getResponseText("TEXT"));
}
// --></script>
<button onclick="btnAjax1()">异步模式</button>
<button onclick="btnAjax2()">非异步模式</button>
</body>
</html>