Service

生命周期

image

1、简介

服务存在两种，
一种事本地服务Local Service，本地服务用于应用程序内部
一种是远程服务Remote Service，用于android 系统内部的应用程序之间

2、本地服务

本地服务通常有两种启动方式: start 启动方式  和 bind启动方式

a、start启动方式

1，onCreate() 创建服务，多次创建方法只运行一次
2，onStartCommand() start一次执行一次
3，onDestroy() 外部调用了stopService或者stopSelf 时执行

• Service代码

  /**
   * start启动
   */
  
  public class LocalService extends Service {
  
    @Override
    public void onCreate() {
        Log.i("Kathy", "onCreate - Thread ID = " + Thread.currentThread().getId());
        super.onCreate();
    }
  
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i("Kathy", "onStartCommand - startId = " + startId + ", Thread ID = " + Thread.currentThread().getId());
        return super.onStartCommand(intent, flags, startId);
    }
  
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        Log.i("Kathy", "onBind - Thread ID = " + Thread.currentThread().getId());
        return null;
    }
  
    @Override
    public void onDestroy() {
        Log.i("Kathy", "onDestroy - Thread ID = " + Thread.currentThread().getId());
        super.onDestroy();
    }
  }
  

• AndroidManifest代码

• Activity代码

  //start启动方式
  Intent service = new Intent(this, LocalService.class);
  startService(service);
  

b，bind启动方式

1，bindService启动的服务和调用者是 client-service 模式，一个service 可以被多个client绑定，
2，同一个界面绑定多次，onCreate、onStartCommand只会执行一次，bind方法可以执行多次
3，当client被销毁时自动与Service解除绑定，client也可以调用unbindService与Service解除绑定，
4，当时Service没有任何client与Service绑定的时候，自动会被销毁

• Service代码

  /**
     * bind服务
  */
  
  public class LocalBindService extends Service {
  
    //client 可以通过Binder 获取Service
    public class LocalBinder extends Binder {
        public LocalBindService getService() {
            return LocalBindService.this;
        }
    }
  
    //Client与Service 之间通讯
    private LocalBinder localBinder = new LocalBinder();
    private final Random random = new Random();
  
    @Override
    public void onCreate() {
        Log.i("Kathy", "LocalBindService - onCreate - Thread = " + Thread.currentThread().getName());
        super.onCreate();
    }
  
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i("Kathy", "LocalBindService - onStartCommand - startId = " + startId + ", Thread = " + Thread.currentThread().getName());
        return super.onStartCommand(intent, flags, startId);
    }
  
  
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        Log.i("Kathy", "LocalBindService - onBind - Thread = " + Thread.currentThread().getName());
        return localBinder;
    }
  
  
    @Override
    public boolean onUnbind(Intent intent) {
        Log.i("Kathy", "LocalBindService - onUnbind - from = " + intent.getStringExtra("from"));
        return super.onUnbind(intent);
    }
  
    @Override
    public void onDestroy() {
        Log.i("Kathy", "LocalBindService - onDestroy - Thread = " + Thread.currentThread().getName());
        super.onDestroy();
    }
  
    //getRandomNumber是Service暴露出去供client调用的公共方法
    public int getRandomNumber() {
        return random.nextInt();
    }
  }
  

• Activity代码

  /**
     * 绑定界面
  */
  
  public class BindServiceActivity extends AppCompatActivity {
  
    private LocalBindService localBindService;
    private boolean isBind = false;
  
    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            isBind = true;
            LocalBindService.LocalBinder localBinder = (LocalBindService.LocalBinder) iBinder;
            localBindService = localBinder.getService();
            Log.i("Kathy", "BindServiceActivity - onServiceConnected");
            int num = localBindService.getRandomNumber();
            Log.i("Kathy", "BindServiceActivity - getRandomNumber = " + num);
        }
  
        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            isBind = false;
            Log.i("Kathy", "BindServiceActivity - onServiceDisconnected");
        }
    };
  
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.bind_service_main);
  
    }
  
    //绑定服务
    public void bind(View view) {
        Intent bindService = new Intent(this, LocalBindService.class);
        Log.i("Kathy", "BindServiceActivity - bind");
        bindService(bindService, serviceConnection, BIND_AUTO_CREATE);
    }
  
    //解除绑定
    public void unbind(View view) {
        Log.i("Kathy", "BindServiceActivity - unbind");
        unbindService(serviceConnection);
    }
  
    //下一个页面
    public void next(View view) {
        Intent intent = new Intent(this, BindServiceActivity.class);
        startActivity(intent);
        finish();
    }
  
    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("Kathy", "BindServiceActivity - onDestroy");
    }
  }
  

2、远程服务

远程服务也被称为独立进程，它可以用于两种情况
1，同一个app中运行
2，不同app中运行

a，AIDL接口的创建

远程服务需要通过AIDL定义的接口提供给client

注：如果服务端与客户端不在同一App上，需要在客户端、服务端两侧都建立该aidl文件。

Android Studio 中的新建栏目里面存在一个可以直接创建的选择

image.png

• IMyAidlInterface代码

  // IMyAidlInterface.aidl
  package poetry.com.service.remote;
  
  // Declare any non-default types here with import statements
  
  interface IMyAidlInterface {
      /**
       * Demonstrates some basic types that you can use as parameters
       * and return values in AIDL.
       */
      String getValue();
  }
  

b，Service的创建

/**
 * 远程服务
 */

public class RemoteService extends Service {

    private final Random random = new Random();

    //实现接口中暴露给客户端的stub
    private IMyAidlInterface.Stub stub = new IMyAidlInterface.Stub() {
        @Override
        public String getValue() throws RemoteException {
            return getRandomNumber();
        }
    };

    @Override
    public void onCreate() {
        Log.i("Kathy", "RemoteService - onCreate - Thread = " + Thread.currentThread().getName());
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i("Kathy", "RemoteService - onStartCommand - startId = " + startId + ", Thread = " + Thread.currentThread().getName());
        return super.onStartCommand(intent, flags, startId);
    }


    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        Log.i("Kathy", "RemoteService - onBind - Thread = " + Thread.currentThread().getName());
        return stub;
    }


    @Override
    public boolean onUnbind(Intent intent) {
        Log.i("Kathy", "RemoteService - onUnbind - from = " + intent.getStringExtra("from"));
        return super.onUnbind(intent);
    }

    @Override
    public void onDestroy() {
        Log.i("Kathy", "RemoteService - onDestroy - Thread = " + Thread.currentThread().getName());
        super.onDestroy();
    }

    //getRandomNumber是Service暴露出去供client调用的公共方法
    public String getRandomNumber() {
        return random.nextInt() + "";
    }
}

c，AndroidMainfest配置

注意：
andorid:process属性设置
1，私有进程以冒号‘:’为前缀，这表示新的进程名为yourPackage:remote，其他应用的组件不可以和它运行在同一进程中
2，全局进程不以冒号‘:’为前缀，以小写字母开头，表示其他应用可以通过设置相同的ShareUID和它运行在同一个进程中

d，Activity的使用

/**
 * 远程服务界面
 */

public class RemoteServiceActivity extends AppCompatActivity {

    private IMyAidlInterface iMyAidlInterface;


    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            iMyAidlInterface = IMyAidlInterface.Stub.asInterface(iBinder);

            Log.i("Kathy", "RemoteServiceActivity - onServiceConnected");
            String num = null;
            try {
                num = iMyAidlInterface.getValue();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
             Log.i("Kathy", "RemoteServiceActivity - getRandomNumber = " + num);
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            Log.i("Kathy", "RemoteServiceActivity - onServiceDisconnected");
            // 断开连接
            iMyAidlInterface = null;
        }
    };


    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.bind_service_main);

    }

    //绑定服务
   public void bind(View view) {
        Intent bindService = new Intent(this, RemoteService.class);
        Log.i("Kathy", "RemoteServiceActivity - bind");
        bindService(bindService, serviceConnection, BIND_AUTO_CREATE);
    }

    //解除绑定
    public void unbind(View view) {
        Log.i("Kathy", "RemoteServiceActivity - unbind");
        unbindService(serviceConnection);
    }

    //下一个页面
    public void next(View view) {
        Intent intent = new Intent(this, RemoteSecondeActivity.class);
        startActivity(intent);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("Kathy", "RemoteServiceActivity - onDestroy");
        if (serviceConnection != null) {
            unbindService(serviceConnection);
        }
    }
}