在 Android Service 未被绑定的情况下,调用 unbindService(connection) 会报错误:service Service not registered, 所以在解除绑定前要先判断连接是否处于绑定状态.

MainActivity类:

public class MainActivity extends AppCompatActivity {

private MyService.DownloadBinder downloadBinder;

private boolean isBind = false; //是否绑定服务

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

final Button startService = (Button)findViewById(R.id.start_service);

final Button stopService = (Button)findViewById(R.id.stop_service);

final Button bindService = (Button)findViewById(R.id.bind_service);

final Button unbindService = (Button)findViewById(R.id.unbind_service);

startService.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Intent startIntent = new Intent(MainActivity.this, MyService.class);

startService(startIntent);

}

});

stopService.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Intent stopIntent = new Intent(MainActivity.this, MyService.class);

stopService(stopIntent);

}

});

bindService.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Intent bindIntent = new Intent(MainActivity.this, MyService.class);

isBind = bindService(bindIntent, connection, BIND_AUTO_CREATE); //绑定服务

}

});

unbindService.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

if(isBind){ //解除绑定前要判断服务是否是绑定状态,其实此处应该还要加入 connection 是否为null 的判断

unbindService(connection); //解绑服务

isBind = false;

}

}

});

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.menu_main, menu);

return true;

}

@Override

public boolean onOptionsItemSelected(MenuItem item) {

// Handle action bar item clicks here. The action bar will

// automatically handle clicks on the Home/Up button, so long

// as you specify a parent activity in AndroidManifest.xml.

int id = item.getItemId();

//noinspection SimplifiableIfStatement

if (id == R.id.action_settings) {

return true;

}

return super.onOptionsItemSelected(item);

}

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) {

}

};

}

MyService类:

public class MyService extends Service {

private DownloadBinder mBinder = new DownloadBinder();

public MyService() {

}

@Override

public IBinder onBind(Intent intent) {

return mBinder;

}

@Override

public void onCreate() {

super.onCreate();

Log.d("MyService", "onCreate execute");

}

@Override

public int onStartCommand(Intent intent, int flags, int startId) {

Log.d("MyService", "onStartCommand execute");

return super.onStartCommand(intent, flags, startId);

}

@Override

public void onDestroy() {

super.onDestroy();

Log.d("MyService", "onDestroy execute");

}

class DownloadBinder extends Binder{

public void startDownload(){

Log.d("MyService", "startDownload executed");

}

public int getProgress(){

Log.d("MyService", "getProgress executed");

return 0;

}

}

}