如何设置Service / StartForeground正确工作CountDownTimer

我不知道在哪里/如何运行此服务在后台工作。 我开发了使用CountDownTimer的应用程序。 我发现我应该在Service.class中创建一个CountDownTimer并在MainActivity.class中运行一个Service.class。

1. 为什么TextView不会在我的屏幕上显示？ 我把它放在OnCreate和onStartCommand中。 接下来我尝试在MainActivity中运行它，但没有成功。

2. 我仍然尝试实现我的代码以在后台正确地使用此CountDownTimer。 在官方Android网站上，我看到他们使用“Log.i”命令来运行此Foreground方法。 我如何在我的代码中使用它？ 我应该在Service.class中添加它吗？

以下是我的代码：

主要活动：

Button btnStart, btnStop; TextView textViewTime; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void startService(View view) { Intent intent = new Intent(this,MyService.class); startService(intent); } public void stopService(View view) { Intent intent = new Intent(this,MyService.class); stopService(intent); } 

为MyService：

 Button btnStart, btnStop; TextView textViewTime; public String hms; @Override public void onCreate() { btnStart = (Button) btnStart.findViewById(R.id.btnStart); btnStop = (Button) btnStop.findViewById(R.id.btnStop); textViewTime = (TextView) textViewTime.findViewById(R.id.textViewTime); textViewTime.setText("00:01:30"); final CounterClass timer = new CounterClass(90000, 1000); btnStart.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //startService(v); timer.start(); } }); super.onCreate(); } @Override public int onStartCommand(Intent intent, int flags, int startId) { // create start a service textViewTime.setText("00:01:30"); Toast.makeText(this, "Service Started...", Toast.LENGTH_LONG).show(); // timer.start(); //return START_STICKY; // return integer value return super.onStartCommand(intent, flags, startId); } @Override public void onDestroy() { // stop a service Toast.makeText(this, "Service Destroyed...", Toast.LENGTH_LONG).show(); super.onDestroy(); } @Nullable @Override public IBinder onBind(Intent intent) { // it's not needed but we must override this method return null; } public class CounterClass extends CountDownTimer { public CounterClass(long millisInFuture, long countDownInterval) { super(millisInFuture, countDownInterval); } @Override public void onTick(long millisUntilFinished) { long millis = millisUntilFinished; hms = String.format("%02d:%02d:%02d", TimeUnit.MILLISECONDS.toHours(millis), TimeUnit.MILLISECONDS.toMinutes(millis) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millis)), TimeUnit.MILLISECONDS.toSeconds(millis) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis))); System.out.println(hms); textViewTime.setText(hms); } @Override public void onFinish() { textViewTime.setText("Completed."); } } 

Answer 1

这是你的解决方案很容易:)

活动xml

Java代码

 import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.os.Bundle; import android.support.v4.content.LocalBroadcastManager; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.TextView; import in.ashish29agre.stackoverflow.R; public class ServiceTimerActivity extends AppCompatActivity { TextView textViewTime; private TimerStatusReceiver receiver; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_service_timer); textViewTime = (TextView) findViewById(R.id.status_tv); receiver = new TimerStatusReceiver(); } @Override protected void onResume() { super.onResume(); LocalBroadcastManager.getInstance(this).registerReceiver(receiver, new IntentFilter(CountdownTimerService.TIME_INFO)); } @Override protected void onPause() { super.onPause(); LocalBroadcastManager.getInstance(this).unregisterReceiver(receiver); } public void startService(View view) { Intent intent = new Intent(this, CountdownTimerService.class); startService(intent); } public void stopService(View view) { Intent intent = new Intent(this, CountdownTimerService.class); stopService(intent); } private class TimerStatusReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { if (intent != null && intent.getAction().equals(CountdownTimerService.TIME_INFO)) { if (intent.hasExtra("VALUE")) { textViewTime.setText(intent.getStringExtra("VALUE")); } } } } } 

服务代码

 import android.app.Notification; import android.app.PendingIntent; import android.app.Service; import android.content.Intent; import android.os.CountDownTimer; import android.os.IBinder; import android.support.annotation.Nullable; import android.support.v4.content.LocalBroadcastManager; import android.support.v7.app.NotificationCompat; import java.util.concurrent.TimeUnit; import in.ashish29agre.stackoverflow.R; public class CountdownTimerService extends Service { public static final String TIME_INFO = "time_info"; private CounterClass timer; @Override public void onCreate() { super.onCreate(); } @Nullable @Override public IBinder onBind(Intent intent) { return null; } @Override public int onStartCommand(Intent intent, int flags, int startId) { timer = new CounterClass(90000, 1000); timer.start(); Intent notificationIntent = new Intent(this, ServiceTimerActivity.class); PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, Intent.FLAG_ACTIVITY_NEW_TASK); Notification notification = new NotificationCompat.Builder(this) .setSmallIcon(R.drawable.ic_launcher) .setContentText("Counter down service") .setContentIntent(pendingIntent).build(); startForeground(101, notification); return START_NOT_STICKY; } @Override public void onDestroy() { timer.cancel(); super.onDestroy(); Intent timerInfoIntent = new Intent(TIME_INFO); timerInfoIntent.putExtra("VALUE", "Stopped"); LocalBroadcastManager.getInstance(CountdownTimerService.this).sendBroadcast(timerInfoIntent); } public class CounterClass extends CountDownTimer { public CounterClass(long millisInFuture, long countDownInterval) { super(millisInFuture, countDownInterval); } @Override public void onTick(long millisUntilFinished) { long millis = millisUntilFinished; String hms = String.format("%02d:%02d:%02d", TimeUnit.MILLISECONDS.toHours(millis), TimeUnit.MILLISECONDS.toMinutes(millis) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millis)), TimeUnit.MILLISECONDS.toSeconds(millis) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis))); System.out.println(hms); Intent timerInfoIntent = new Intent(TIME_INFO); timerInfoIntent.putExtra("VALUE", hms); LocalBroadcastManager.getInstance(CountdownTimerService.this).sendBroadcast(timerInfoIntent); } @Override public void onFinish() { Intent timerInfoIntent = new Intent(TIME_INFO); timerInfoIntent.putExtra("VALUE", "Completed"); LocalBroadcastManager.getInstance(CountdownTimerService.this).sendBroadcast(timerInfoIntent); } } } 

忘记提及需要在清单中添加服务

Answer 2

首先 ：

您必须在MainActivity.java中编写Broadcast Receiver并在oncreate() register它，并在oncreate() unregister 。

其次

在onTick()方法的Service中，你必须发送sendbroadcast() ，它将在MainActivity.java中调用onReceive() ，然后在onReceive方法中你可以chage text of Textview活动chage text of Textview 。