Question

我在Android应用中使用AsyncTask调用Web服务，我无法弄清楚如何等到onPostExecute完成：

//Call Async Web Service here 
AsyncCallWS task = new AsyncCallWS();
task.execute();
//Need to wait to fill this in ** Its not  waiting.
String sCall = rslt;
String[] aCall = sCall.split("//|");

private class AsyncCallWS extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() {
        Log.i(TAG, "onPreExecute");
    }
    @Override
    protected Void doInBackground(Void... params) {
        Log.i(TAG, "doInBackground");
        GetURL();
        return null;
    }
    @Override
    protected void onPostExecute(Void result) {
        Log.i(TAG, "onPostExecute");
        try{
            //Results HERE
            rslt = resultString.toString();
        }
        catch(Exception ex)
        {rslt = ex.toString()+ "|" + ex.toString();}

    }
}

Answer 1

我不清楚你可以从onPostExecute做什么，但是如果你想要执行一些没有耦合的东西，你可以使用回调任务（以便您可以从任何地方运行任务）

private class OnFinishedListener {
    void onFinished(String rslt);
}

private class AsyncCallWS extends AsyncTask<Void, Void, Void> {

    private OnFinishedListener mAfter;

    public AsyncCallWS(OnFinishedListener after) {
        mAfter = after;
    }

    ...

    @Override
    protected void onPostExecute(Void result) {
        ....
        if (mAfter != null) {
            //you didnt illustrate what resultString is, you might
            //want this to be the returned value from doInBackground
            mAfter.onFinished(resultString.toString());
        }
    }

}

用法

new AsyncCallWS(new OnFinishedListener {
    public void onFinished(String rslt) {
        //for example
        String sCall = rslt;
        String[] aCall = sCall.split("//|");
    }
}).execute();

Answer 2

您可以在后台线程中使用Tasks.await(task)。不要在UI线程中使用它。您还可以为任务Tasks.await(task, 500, TimeUnit.MILLISECONDS);

设置超时

Answer 3

使用getStatus（）方法。

while (task.getStatus() != Status.FINISHED);

更好的方法是在split()方法中调用onPostExecute()，因为onPostExecute()无论如何都会在UI线程上运行，而while()调用会阻止当前线程正在运行。

Android AsyncTask等到完成

3 个答案: