使用xutils3.5.0进行文件下载，onloading（）方法不执行，但是最终onsucess（）执行了

x.http().get(params, new Callback.ProgressCallback<File>() {
            @Override
            public void onSuccess(File result) {
                Log.d("zw---","sucess");            }            @Override
            public void onError(Throwable ex, boolean isOnCallback) {
                Log.d("error===",ex.getMessage());
            }            @Override
            public void onCancelled(CancelledException cex) {
                Log.d("zw---","cancle");            }            @Override
            public void onFinished() {
                Log.d("zw---","finish");            }            //网络请求之前回调
            @Override
            public void onWaiting() {
                Log.d("zw---","waitting");            }            //网络请求开始的时候回调
            @Override
            public void onStarted() {
                Log.d("zw---","start");            }            //下载的时候不断回调的方法
            @Override
            public void onLoading(long total, long current, boolean isDownloading) {
                if(isDownloading){
                    Log.d("zw---","load"+current);                    //当前进度和文件总大小
                    Log.i("JAVA", "current：" + current + "，total：" + total);
                }else {
                    Log.d("zw---","load"+isDownloading);
                }
            }
============AS 控制台Log信息===================
08-15 16:51:56.404 24055-24055/com.example.zw_pc.xutilsdemo D/zw--: begin
08-15 16:51:56.435 24055-24055/com.example.zw_pc.xutilsdemo D/zw---: waitting
08-15 16:51:56.435 24055-24055/com.example.zw_pc.xutilsdemo D/zw---: start
08-15 16:51:56.538 24055-24132/com.example.zw_pc.xutilsdemo I/DpmTcmClient: RegisterTcmMonitor from: com.android.okhttp.TcmIdleTimerMonitor
08-15 16:52:01.839 24055-24055/com.example.zw_pc.xutilsdemo D/zw---: sucess
08-15 16:52:01.841 24055-24055/com.example.zw_pc.xutilsdemo D/zw---: finish