AJAX+jsp无刷新验证码实例

来源：作者：出处：巧巧读书 2007-07-19 进入讨论组

4,net.js,封装好的xmlhttp对象，可以很方便的调用

/* namespacing object */
var net=new Object();

net.READY_STATE_UNINITIALIZED=0;
net.READY_STATE_LOADING=1;
net.READY_STATE_LOADED=2;

net.READY_STATE_INTERACTIVE=3;
net.READY_STATE_COMPLETE=4;
/*--- content loader object for cross-browser requests ---*/
net.ContentLoader=function(url,on_load,on_error,method,params,contentType){
this.req=null;
this.on_load=on_load;
this.on_error=(on_error) ? on_error : this.defaultError;
this.loadXMLDoc(url,method,params,contentType);
}
net.ContentLoader.prototype.loadXMLDoc=function(url,method,params,contentType){
if (!method)
{
method="GET";
}
if (!contentType && method=="POST")
{
contentType='application/x-www-form-urlencoded';
}
if (window.XMLHttpRequest)
{
this.req=new XMLHttpRequest();
}
else if (window.ActiveXObject)
{
//add try catch;
try {
      this.req = new ActiveXObject("Msxml2.XMLHTTP");
   }catch (e1){
     try {
      this.req = new ActiveXObject("Microsoft.XMLHTTP");
      } catch (e2){
    }
   }
    //
//this.req=new ActiveXObject("Microsoft.XMLHTTP");
}
if (this.req)
{
try
{
   var loader=this;
   this.req.onreadystatechange=function()
   {
  net.ContentLoader.onReadyState.call(loader);
   }
   this.req.open(method,url,true);
   if (contentType)
   {
    this.req.setRequestHeader('Content-Type', contentType);
   }
   this.req.send(params);
}
catch (err)
{
   this.on_error.call(this);
}
}
}
net.ContentLoader.onReadyState=function(){
var req=this.req;
var ready=req.readyState;
if (ready==net.READY_STATE_COMPLETE){
var httpStatus=req.status;
if (httpStatus==200 || httpStatus==0){
   this.on_load.call(this);
}else{
   this.on_error.call(this);
}
}
}
net.ContentLoader.prototype.defaultError=function(){
alert("error fetching data!"
+"\n\nreadyState:"+this.req.readyState
+"\nstatus: "+this.req.status
+"\nheaders: "+this.req.getAllResponseHeaders());
}

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