使用 AsyncTaskLoader 时,如何更新显示更新状态的进度条?通常,您会等待回调完成后删除,但是如何进行运行更新呢?
您会让主线程(ui)在设置数据时轮询数据吗?
编辑:我正在谈论异步任务加载器,看loader部分。这是课程链接:http://developer.android.com/reference/android/content/AsyncTaskLoader.html http://developer.android.com/reference/android/content/AsyncTaskLoader.html
我想使用它,因为它是未来:),我知道如何使用 AsyncTask 来做到这一点。
您可以使用加载器来做到这一点,但您需要保留并更新 Activity 上的 WeakReference :
public class LoaderTestActivity extends FragmentActivity implements LoaderCallbacks<Void> {
private static final int MAX_COUNT = 100;
private ProgressBar progressBar;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_async_task_test);
progressBar = (ProgressBar) findViewById(R.id.progressBar1);
progressBar.setMax(MAX_COUNT);
AsyncTaskCounter.mActivity = new WeakReference<LoaderTestActivity>(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_async_task_test, menu);
return true;
}
public void onStartButtonClick(View v) {
startWork();
}
void startWork() {
getSupportLoaderManager().initLoader(0, (Bundle) null, this);
}
static class AsyncTaskCounter extends AsyncTaskLoader<Void> {
static WeakReference<LoaderTestActivity> mActivity;
AsyncTaskCounter(LoaderTestActivity activity) {
super(activity);
mActivity = new WeakReference<LoaderTestActivity>(activity);
}
private static final int SLEEP_TIME = 200;
@Override
public Void loadInBackground() {
for (int i = 0; i < MAX_COUNT; i++) {
try {
Thread.sleep(SLEEP_TIME);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.d(getClass().getSimpleName(), "Progress value is " + i);
Log.d(getClass().getSimpleName(), "getActivity is " + getContext());
Log.d(getClass().getSimpleName(), "this is " + this);
final int progress = i;
if (mActivity.get() != null) {
mActivity.get().runOnUiThread(new Runnable() {
@Override
public void run() {
mActivity.get().progressBar.setProgress(progress);
}
});
}
}
return null;
}
}
@Override
public Loader<Void> onCreateLoader(int id, Bundle args) {
AsyncTaskLoader<Void> asyncTaskLoader = new AsyncTaskCounter(this);
asyncTaskLoader.forceLoad();
return asyncTaskLoader;
}
@Override
public void onLoadFinished(Loader<Void> arg0, Void arg1) {
}
@Override
public void onLoaderReset(Loader<Void> arg0) {
}
}
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