javascript Ajax 类实现代码

    }

    //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"))){