请教：dwr的batch和hooks

Question

dwr官网上说：The global preHook is called before the batch and call preHooks. The global
postHook is called after the call and batch postHooks.可是我试出来怎么不一样呢？代码如下：
function batchHookTest(){
    DWREngine.setPreHook(function(){
        engineTestCallbackHandler("global_preHook");});
    DWREngine.setPostHook(function(){
        engineTestCallbackHandler("global_postHook");});    DWREngine.setAsync(false);    DWREngine.beginBatch();    EngineTest.batchTest("load1", {
        preHook:function(){engineTestCallbackHandler("single_preHook1");},
        postHook:function(){engineTestCallbackHandler("single_postHook1");},
        callback:engineTestCallbackHandler
    });    EngineTest.batchTest("load2", {
        preHook:function(){engineTestCallbackHandler("single_preHook2");},
        postHook:function(){engineTestCallbackHandler("single_postHook2");},
        callback:engineTestCallbackHandler
    });    EngineTest.batchTest("load3", {
        preHook:function(){engineTestCallbackHandler("single_preHook3");},
        postHook:function(){engineTestCallbackHandler("single_postHook3");},
        callback:engineTestCallbackHandler
    });    engineTestCallbackHandler("before_endBatch");    DWREngine.endBatch({
        preHook:function(){engineTestCallbackHandler("batch_preHook");},
        postHook:function(){engineTestCallbackHandler("batch_postHook");},
    });    DWREngine.setAsync(true);
}
function engineTestCallbackHandler(backData){
    $("engineTestShowArea").innerHTML += "<br/>"+backData;
}
打印结果如下：
before_endBatch
batch_preHook
single_preHook3
single_preHook2
single_preHook1
global_preHook
global_postHook
single_postHook1
single_postHook2
single_postHook3
batchTest_load1
batchTest_load2
batchTest_load3