机器人等待的AsyncTask完成 [英] android wait asynctask to finish

问题描述

我有一个函数， AppHelper.isOnline（上下文的背景下），我在我的应用程序的各个部分调用检查会话没有超时作出HTTP前请求。

I have a function, AppHelper.isOnline(Context context), I call in various parts of my application to check that a session didn't timeout before making an HTTP request.

public void onClick(View v) {
        Intent intent = null;
        switch (v.getId()) {

        case R.id.buttonPagamenti:
            if (AppHelper.isOnline(this))
            {
                //here AppHelper.isOnline should have finished it's async task
                intent = new Intent(this, OrdineCreaActivity.class);
                this.startActivityForResult(intent, R.id.buttonPagamenti);
            }
            break;
...

在 AppHelper.isOnline（），我执行异步任务登录，从而使网络请求，不能在用户界面，否则运行我得到一个异常。我需要等待它完成，然后用，如果里面的code恢复。我怎样才能做到这一点？

Inside AppHelper.isOnline(), I am executing an async task that logs in, thus making a network request, which can't be run on UI because otherwise I get an exception. I need to wait for it to finish BEFORE resuming with the code inside the if. How can I do this ?

问题是活动开始首创，然后异步执行，所以当活动需要一个有效的记录的会话，它打破了。

Problem is the activity starts firsts, then the async executes, so when the activity expects a valid logged in session, it breaks.

推荐答案

您有两种选择：

既可以使用的AsyncTask 的方法获取（长期超时的TimeUnit单位）这样的：

Either use the AsyncTask's method get(long timeout, TimeUnit unit) like that:

task.get(1000, TimeUnit.MILLISECONDS);

这会使你的主线程等待的的AsyncTask 至多1000毫秒（根据@ user1028741评论结果：居然还有infinetly等方法 - <一个href="http://developer.android.com/reference/android/os/AsyncTask.html#get%28%29"><$c$c>AsyncTask#get()这可能也是做在某些情况下，你的工作）。

This will make your main thread wait for the result of the AsyncTask at most 1000 milliseconds (as per @user1028741 comment: actually there is also infinetly waiting method - AsyncTask#get() which might also do the work for you in some cases).

另外，您可以显示进度的异步任务对话框，直到它完成。看到这个线程（不用我复制过去code）。主要是显示一个进度对话框，而异步任务运行和隐藏，当它完成。

Alternatively you can show a progress dialog in the async task until it finishes. See this thread (No need for me to copy past the code). Basically a progress dialog is shown while the async task runs and is hidden when it finishes.

您甚至有第三个选择：如果发是足以满足你的需要，你可以只使用它的加入方法但是，如果任务花费很长一段时间，你仍然需要显示进度对话框，否则你会得到，因为主线程处于非活动状态的时间太长的一个例外。

You have even third option:" if Thread is sufficient for your needs you can just use its join method. However, if the task is taking a long while you will still need to show a progress dialog, otherwise you will get an exception because of the main thread being inactive for too long.

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