深入分析DWREngine.endBatch
DWREngine.endBatch将在DWREngine._execute最后被调用
（--〉DWREngine._execute--〉DWREngine.endBatch）
/**
* Finished grouping a set of remote calls together. Go and execute them all.
* @see http://getahead.ltd.uk/dwr/browser/engine/batch
*/
//函数定义
DWREngine.endBatch = function(options) {
//设置请求对象
var batch = DWREngine._batch;
//请求对象为空返回
if (batch == null) {
DWREngine._handleError("No batch in progress.");
return;
}
// Merge the global batch level properties into the batch meta data
//如果形参存在那么有如下两步，通常行参是不存在的， 在DWREngine._execute中是如此调用endBatch的：DWREngine.endBatch();
if (options && options.preHook) batch.preHooks.unshift(options.preHook);
if (options && options.postHook) batch.postHooks.push(options.postHook);
//除非你写程序时调用过DWREngine.setPreHook,否则下面代码无用
if (DWREngine._preHook) batch.preHooks.unshift(DWREngine._preHook);
//除非你写程序时调用过DWREngine.setPostHook,否则下面代码无用
if (DWREngine._postHook) batch.postHooks.push(DWREngine._postHook);
//除非你手工改过源代码，否则下面的4个判断条件肯定为真
//DWREngine._method默认为1，表示采用XMLHttpRequest,除非你写程序时调用过DWREngine.setMethod
if (batch.method == null) batch.method = DWREngine._method;
//DWREngine._verb默认为"post"，除非你写程序时调用过DWREngine.setVerb
if (batch.verb == null) batch.verb = DWREngine._verb;
//DWREngine._async默认为true，表示请求是异步的,除非你写程序时调用过DWREngine.setAsync
if (batch.async == null) batch.async = DWREngine._async;
//DWREngine.timeout 默认为0，除非你写程序时调用过DWREngine.setTimeout，
if (batch.timeout == null) batch.timeout = DWREngine._timeout;
//标记请求未完成
batch.completed = false;
// We are about to send so this batch should not be globally visible
//将DWREngine._batch赋值给临时变量batch后，将DWREngine._batch设为空
DWREngine._batch = null;
// If we are in ordered mode, then we don't send unless the list of sent
// items is empty
//判断DWREngine._ordered，默认为false
if (!DWREngine._ordered) {
DWREngine._sendData(batch);
//将请求对象放入请求数组，暂时没看出有什么用
DWREngine._batches[DWREngine._batches.length] = batch;
}
//如果通过调用DWREngine.setOrdered设置了_ordered，那么会使用_batchQueue，且进入下面的else块，否则不用理会下面的代码
else {
if (DWREngine._batches.length == 0) {
// We aren't waiting for anything, go now.
DWREngine._sendData(batch);
DWREngine._batches[DWREngine._batches.length] = batch;
}
else {
// Push the batch onto the waiting queue
DWREngine._batchQueue[DWREngine._batchQueue.length] = batch;
}
}
};
总结：
此函数主要是设置请求对象属性：_preHooks，postHooks，method，verb ，async ，timeout
然后调用DWREngine._sendData(batch);最后将请求加入数组或队列