标签：super build color 状态 void layout XML hand xtend
10.3 Service的基本用法
10.3.1 定义一个服务
New——>Service
public class MyService extends Service { public MyService() { } @Override public IBinder onBind(Intent intent) { // TODO: Return the communication channel to the service. throw new UnsupportedOperationException("Not yet implemented"); } }
重写3个方法
//服务创建时调用
@Override public void onCreate() { super.onCreate(); } //每次服务启动时调用 @Override public int onStartCommand(Intent intent, int flags, int startId) { return super.onStartCommand(intent, flags, startId); } //服务销毁时调用 @Override public void onDestroy() { super.onDestroy(); }
在AndroidManifest.xml中已经自动注册好
<service android:name=".MyService" android:enabled="true" android:exported="true"></service>
10.3.2 启动和停止服务
修改activity_main中的代码，在布局中加两个按钮用于启动和停止服务
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <Button android:id="@+id/start_service" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Start Service"/> <Button android:id="@+id/stop_service" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Stop Service"/> </LinearLayout>
修改MainActivity中的代码，构建Intent对象来启动和停止服务
public class MainActivity extends AppCompatActivity implements View.OnClickListener{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button startService = (Button)findViewById(R.id.start_service); Button stopService = (Button)findViewById(R.id.stop_service); startService.setOnClickListener(this); stopService.setOnClickListener(this); } @Override public void onClick(View v) { switch(v.getId()){ case R.id.start_service: Intent startIntent = new Intent(this, MyService.class); startService(startIntent); break; case R.id.stop_service: Intent stopIntent = new Intent(this, MyService.class); stopService(stopIntent); break; } } }
在MyService中增加打印日志
@Override public void onCreate() { super.onCreate(); Log.d("MyService","onCreate executed"); } @Override public int onStartCommand(Intent intent, int flags, int startId) { Log.d("MyService","onStartCommand executed"); return super.onStartCommand(intent, flags, startId); } @Override public void onDestroy() { Log.d("MyService","onDestroy executed"); super.onDestroy(); }
运行程序，点击按钮
10.3.3 活动和服务进行通信
活动和服务之间通信需要借助onBind()方法。
比如希望在MyService中提供一个下载功能，然后在活动中决定何时开始下载，以及随时查看下载进度。
创建一个专门的Binder对象来对下载功能进行管理。修改MyService中的代码。
public class MyService extends Service { private DownloadBinder mBinder = new DownloadBinder(); class DownloadBinder extends Binder { public void startDownload(){ Log.d("MyService","startDownload executed"); } public int getProgress(){ Log.d("MyService","getProgress executed"); return 0; } } public MyService() { } @Override public IBinder onBind(Intent intent) { 1 } @Override public void onCreate() { super.onCreate(); Log.d("MyService","onCreate executed"); } @Override public int onStartCommand(Intent intent, int flags, int startId) { Log.d("MyService","onStartCommand executed"); return super.onStartCommand(intent, flags, startId); } @Override public void onDestroy() { Log.d("MyService","onDestroy executed"); super.onDestroy(); } }
在activity_main中添加两个按钮用于绑定和解绑服务
<Button android:id="@+id/bind_service" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Bind Service"/> <Button android:id="@+id/unbind_service" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Unbind Service"/>
修改MainActivity中的代码
当活动和服务绑定后，就可以调用该服务中Binder提供的方法了。
首先创建一个ServiceConnection的匿名类，在里面重写onServiceConnected()方法和onServiceDisconnected()方法，分别在活动与服务成功绑定以及活动与服务的连接断开的时候调用。
在onServiceConnected()方法中调用了DownloadBinder的startDownload()和getProgress()方法。
public class MainActivity extends AppCompatActivity implements View.OnClickListener{ private MyService.DownloadBinder downloadBinder; private ServiceConnection connection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { downloadBinder = (MyService.DownloadBinder) service; downloadBinder.startDownload(); downloadBinder.getProgress(); } @Override public void onServiceDisconnected(ComponentName name) { } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button startService = (Button)findViewById(R.id.start_service); Button stopService = (Button)findViewById(R.id.stop_service); Button bindService = (Button)findViewById(R.id.bind_service); Button unbindService = (Button)findViewById(R.id.unbind_service); startService.setOnClickListener(this); stopService.setOnClickListener(this); bindService.setOnClickListener(this); unbindService.setOnClickListener(this); } @Override public void onClick(View v) { switch(v.getId()){ case R.id.start_service: Intent startIntent = new Intent(this, MyService.class); startService(startIntent); break; case R.id.stop_service: Intent stopIntent = new Intent(this, MyService.class); stopService(stopIntent); break; case R.id.bind_service: Intent bindIntent = new Intent(this, MyService.class); bindService(bindIntent, connection, BIND_AUTO_CREATE); //绑定服务 break; case R.id.unbind_service: unbindService(connection); //解绑服务 break; default: break; } } }
运行程序：
10.4 Service的生命周期
10.5 Service的更多技巧
10.5.1 使用前台服务
希望服务可以一直保持运行状态，而不会由于系统内存不足的原因导致被回收，可以考虑使用前台服务。
前台服务和普通服务最大的区别在于，它会有一个正在运行的图标在系统的状态栏显示，下拉状态栏可以看到更加详细的信息，非常类似于通知的效果。
修改MyService中的代码
@Override public void onCreate() { super.onCreate(); Log.d("MyService","onCreate executed"); Intent intent = new Intent(this,MainActivity.class); PendingIntent pi = PendingIntent.getActivity(this, 0, intent, 0); Notification notification = new NotificationCompat.Builder(this,"default") .setContentTitle("This is content title") .setContentText("This is content text") .setWhen(System.currentTimeMillis()) .setSmallIcon(R.mipmap.ic_launcher) .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher)) .setContentIntent(pi) .build(); startForeground(1, notification); }
类似于创建通知的方法。
运行程序：
10.5.2 使用IntentService
服务中的代码都是默认运行在主线程当中的，如果直接在服务里去处理一些耗时的逻辑，就很容易出现ANR（Application Not Responding/应用程序未响应）的情况。
Android专门提供了一个IntentService类，这个类很好的解决了忘记开启线程或忘记停止服务。
新建一个类继承IntentService
public class MyIntentService extends IntentService { public MyIntentService(){ super("MyIntentService"); } @Override protected void onHandleIntent(Intent intent) { //打印当前线程的id Log.d("MyIntentService", "Thread id is " + Thread.currentThread().getId()); } @Override public void onDestroy() { super.onDestroy(); Log.d("MyIntentService","onDestroy executed"); //打印日志以证明服务停止 } }
在activity_main中添加一个Button
<Button android:id="@+id/start_intent_service" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Start IntentService"/>
修改MainActivity中的代码
public class MainActivity extends AppCompatActivity implements View.OnClickListener{ private MyService.DownloadBinder downloadBinder; private ServiceConnection connection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { downloadBinder = (MyService.DownloadBinder) service; downloadBinder.startDownload(); downloadBinder.getProgress(); } @Override public void onServiceDisconnected(ComponentName name) { } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button startService = (Button)findViewById(R.id.start_service); Button stopService = (Button)findViewById(R.id.stop_service); Button bindService = (Button)findViewById(R.id.bind_service); Button unbindService = (Button)findViewById(R.id.unbind_service); Button startIntentService = (Button)findViewById(R.id.start_intent_service); startService.setOnClickListener(this); stopService.setOnClickListener(this); bindService.setOnClickListener(this); unbindService.setOnClickListener(this); startIntentService.setOnClickListener(this); } @Override public void onClick(View v) { switch(v.getId()){ case R.id.start_service: Intent startIntent = new Intent(this, MyService.class); startService(startIntent); break; case R.id.stop_service: Intent stopIntent = new Intent(this, MyService.class); stopService(stopIntent); break; case R.id.bind_service: Intent bindIntent = new Intent(this, MyService.class); bindService(bindIntent, connection, BIND_AUTO_CREATE); //绑定服务 break; case R.id.unbind_service: unbindService(connection); //解绑服务 break; case R.id.start_intent_service: Log.d("MainActivity", "Thread id is " + Thread.currentThread().getId()); Intent intentService = new Intent(this, MyIntentService.class); startService(intentService); break; default: break; } } }
最后在AndroidManifest中注册
<service android:name=".MyIntentService"/>
运行程序：
MyIntentService和MainActivity所在的线程id不一样，而且onDestroy()方法也得到了执行，说明MyIntentService在运行完毕确实自动停止了，集开启线程和自动停止于一身。
<Android基础> (十）Service Part 2 基本用法
标签：super build color 状态 void layout XML hand xtend
原文地址：https://www.cnblogs.com/HarSong13/p/10833051.html
