android onstop,android-在Activity的onStop()期间删除片段

总体建议是避免响应异步事件而提交事务.有关更多信息,请参见this article.但是,有时这是不可避免的,您可以设置一些更复杂的状态检查和恢复.

对于您的特定情况(似乎您希望网络请求在“活动”不再可见时立即停止),您可以采取以下措施：

public class SampleActivity extends FragmentActivity {

private static final String PROGRESS_FRAGMENT = "progress_fragment";

@Override

protected void onStart() {

super.onStart();

refreshData();

}

private void refreshData() {

if (!isInProgress) {

isInProgress = true;

showSpinner();

}

}

private void cancelRefresh() {

if (isInProgress) {

isInProgress = false;

//cancel request

hideSpinner();

}

}

private void showSpinner() {

getSupportFragmentManager()

.beginTransaction()

.add(new ProgressFragment(), PROGRESS_FRAGMENT)

.commit();

}

private void hideSpinner() {

FragmentManager mgr = getSupportFragmentManager();

Fragment spinner = mgr.findFragmentByTag(PROGRESS_FRAGMENT);

if (spinner != null) {

mgr.beginTransaction()

.remove(spinner)

.commit();

}

}

@Override

protected void onSaveInstanceState(Bundle outState) {

super.onSaveInstanceState(outState);

cancelRefresh();

}

@Override

protected void onStop() {

super.onStop();

cancelRefresh();

}

}

由于您不知道将调用onSaveInstanceState(),因此可以在onSaveInstanceState()和onStop()上调用cancel.设置了标志并使用了用于跟踪片段的标记,它将仅执行一次,并且应该是安全的.