使用 AsyncTask 在后台服务中添加 Android 进度对话框，出现致命异常

1. 我正在打电话异步任务从预定服务每 10 分钟运行一次。

2. 运行服务时，进度对话框从以下位置获取异常预执行.

ERROR :

FATAL EXCEPTION: main                                                                                    
android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
at android.view.ViewRootImpl.setView(ViewRootImpl.java:594)

at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:259)

at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)

at android.app.Dialog.show(Dialog.java:286)

EDIT 1: 警报管理器每 5 分钟调用一次服务

/*Alarm manager Service for From Server*/
private void setServerFetch() {
    // for  to Server to GPS PING
    Intent myIntent1 = new Intent(LoginPage.this, AlarmService.class);
    pendingintent1 = PendingIntent.getService(LoginPage.this, 1111, myIntent1, 0);
    AlarmManager alarmManager5 = (AlarmManager) getSystemService(ALARM_SERVICE);
    Calendar calendar1 = Calendar.getInstance();
    calendar1.setTimeInMillis(System.currentTimeMillis());
    calendar1.add(Calendar.SECOND, 1);
    alarmManager5.set(AlarmManager.RTC_WAKEUP, calendar1.getTimeInMillis(), pendingintent1);
    alarmManager5.setInexactRepeating(AlarmManager.RTC_WAKEUP, calendar1.getTimeInMillis(), 300 * 1000, pendingintent1);

}

呼叫服务 Onstart 中的 AsyncTask

 @Override
    public void onStart(Intent intent, int startId)
    {
        super.onStart(intent, startId);


        try
        {

                Asynctask_Incident task=new Asynctask_Incident();
                task=new();

        }
        catch (Exception e)
        {
            e.printStackTrace();
            Log.i("PING", "EXCEPTION in reading Data from Web Async task ONstart.!");

        }

    }

异步任务类onStart Method

public class Asynctask_Incident extends AsyncTask<String, Void, Void>
    {


        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();

            runOnUiThread(new Runnable() {

                @Override
                public void run() {

                    if (!pDialog.isShowing())
                    {
                        pDialog = new ProgressDialog(appContext);
                        pDialog.setCanceledOnTouchOutside(false);
                        pDialog.setCancelable(false);
                        pDialog.setMessage("Please Wait Updating Data From...");
                        pDialog.show();
                    }
                }
            });


        }

        @Override
        protected Void doInBackground(String... params)
        {
            try {
                getAPICall();

            } catch (Exception e) {
                e.printStackTrace();

                if (pDialog.isShowing()) {
                    pDialog.dismiss();
                }

            }

            return null;
        }
        @Override
        protected void onPostExecute(Void aVoid)
        {

            super.onPostExecute(aVoid);

            if (pDialog.isShowing()) {
                pDialog.dismiss();
            }


        }


    }

帮助我解决这个问题。

实际上，您无法从服务启动进度对话框，因为它需要活动上下文而不是应用程序上下文，在您的情况下，应用程序上下文为空。

更多信息请点击这里：link1 https://stackoverflow.com/a/2639515/831127 , link2 https://stackoverflow.com/a/7229248/831127 and link3 https://stackoverflow.com/a/7933358/831127

如果你想根据服务动作触发进度对话框，你可以使用观察者设计模式，看看here https://stackoverflow.com/a/13347389/831127.

Update:如果您的应用程序正在运行，您可以使用 Handler 并每 5 分钟运行一次。

这是一个完整的例子：

public class TestActivity extends AppCompatActivity {

private Handler handler;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_test);

    handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            //
            new Asynctask_Incident(TestActivity.this).execute("url");
            handler.postDelayed(this, 5 * DateUtils.MINUTE_IN_MILLIS);
        }
    }, 0);
}

public class Asynctask_Incident extends AsyncTask<String, Void, Void> {


    ProgressDialog pDialog;
    Context appContext;

    public Asynctask_Incident(Context ctx) {
        appContext = ctx;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

            pDialog = new ProgressDialog(appContext);
            pDialog.setCanceledOnTouchOutside(false);
            pDialog.setCancelable(false);
            pDialog.setMessage("Please Wait Updating Data From...");
            pDialog.show();


    }

    @Override
    protected Void doInBackground(String... params) {
        try {
            getAPICall();

        } catch (Exception e) {
            e.printStackTrace();

            if (pDialog.isShowing()) {
                pDialog.dismiss();
            }

        }

        return null;
    }

    private void getAPICall() {

        //5 seconds delay for test, you can put your code here
        try {
            Thread.sleep(5 * DateUtils.SECOND_IN_MILLIS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onPostExecute(Void aVoid) {

        super.onPostExecute(aVoid);

        if (pDialog.isShowing()) {
            pDialog.dismiss();
        }


    }


}

}