android如何在按下后退按钮时停止异步任务执行

请我有一个包含异步任务方法的活动,即使用户已从该页面移出,该异步任务方法仍在后台继续执行.请提供一种方法,一旦用户按下“后退”按钮或从该页面移至另一页面,即可停止执行异步任务.

以下是我尝试过的方法,但无法正常工作

private AsyncTask totalLikesAsync;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity);
cOntext= this;
totalLikesAsync = new TotalLikes().execute(msgID);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem menuItem) {
switch (menuItem.getItemId()) {
case android.R.id.home:
totalLikesAsync.cancel(true);
this.finish();
break;
case R.id.share:
new ShareImage().execute(msgImage);
default:
return super.onOptionsItemSelected(menuItem);
}
return true;
}

private class TotalLikes extends AsyncTask {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected JSONObject doInBackground(String... msgIDs) {
UserFunctions userFunction = new UserFunctions();
String msgsID = msgIDs[0];
JSONObject json=null;
if(!isCancelled()){
//This gets all the information unread from the server
json = userFunction.TotalLikes(context, msgsID);
}
return json;
}
@Override
protected void onPostExecute(JSONObject json) {
/**
* Checks for success message.
**/
if (json != null) {
...
} else {
...
}
}
}


更新

测试完以下所有答案后,即使按下后退按钮,它们都允许在异步任务中执行doinbackground.我想要一种情况,一旦按下“后退”按钮,背景将被取消.

解决方法:

@Override
public void onBackPressed() {
super.onBackPressed();
if (totalLikesAsync != null && totalLikesAsync.getStatus().equals(AsyncTask.Status.RUNNING)) {
totalLikesAsync.cancel(true);
}
}