DWR->StateBatch

但异步请求提交后，服务端完成请求，dwr框架会调用DWREngine._stateChange来处理返回结果

/**

* @private Called by XMLHttpRequest to indicate that something has happened

*/

DWREngine._stateChange = function(batch) {

//状态正确则进入下面的if块

if (!batch.completed && batch.req.readyState == 4) {

try {

 

//取回返回的文本

var reply = batch.req.responseText;

//请求的状态

var status = batch.req.status;

 

//返回为空或空串则抛意外

if (reply == null || reply == "") {

DWREngine._handleMetaDataError(null, "No data received from server");

return;

}

 

// This should get us out of 404s etc.

//返回串中如果不包含"DWREngine._handle"也抛意外

if (reply.search("DWREngine._handle") == -1) {

DWREngine._handleMetaDataError(null, "Invalid reply from server");

return;

}

 

//状态不对，抛意外

if (status != 200) {

if (reply == null) reply = "Unknown error occured";

DWREngine._handleMetaDataError(null, reply);

return;

}

 

//执行返回的文本，返回的文本实际上是一段脚本

eval(reply);

 

// We're done. Clear up

//完成之后坐清理

DWREngine._clearUp(batch);

}

catch (ex) {

if (ex == null) ex = "Unknown error occured";

DWREngine._handleMetaDataError(null, ex);

}

finally {

// If there is anything on the queue waiting to go out, then send it.

// We don't need to check for ordered mode, here because when ordered mode

// gets turned off, we still process *waiting* batches in an ordered way.

//如果_batchQueue还有任何等待的请求，继续执行

if (DWREngine._batchQueue.length != 0) {

var sendbatch = DWREngine._batchQueue.shift();

DWREngine._sendData(sendbatch);

DWREngine._batches[DWREngine._batches.length] = sendbatch;

}

}

}

};

 

总结：

重点看看到底DWR返回什么，

下面是个真实的例子： 

"var s0={};

var s1=/"666<br><br>ttt/";

s0.content=s1;

var s2=null;

s0.crttime=s2;

var s3=632;

s0.id=s3;

var s4=/"127.0.0.1/";

s0.ip=s4;

var s5=0;

s0.parentId=s5;

var s6=false;

s0.replied=s6;

var s7=/"/";

s0.title=s7;

var s8={};

var s9=false;

s8.anonymous=s9;/n

var s10=null;

s8.createtime=s10;

var s11=/"alex/";

s8.loginName=s11;

。。。。。。。

DWREngine._handleResponse('8781_1152243284156', s0);/n"

 

原来返回的字符串是一段脚本，脚本分为两部分，前一部分是生成一个js对象，对应服务端返回的对象模型，

后一段是调用DWREngine._handleResponse，通过eval函数来执行这段脚本。

&<60;