Android studio 使用Service生成随机数

可以使用 Service 在后台生成随机数。以下是一份示例代码：

public class RandomNumberService extends Service {
    private static final String TAG = "RandomNumberService";
    private final IBinder mBinder = new LocalBinder();
    private final Random mGenerator = new Random();

    @Override
    public void onCreate() {
        Log.d(TAG, "onCreate");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d(TAG, "onStartCommand");
        return START_NOT_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        Log.d(TAG, "onBind");
        return mBinder;
    }

    public class LocalBinder extends Binder {
        RandomNumberService getService() {
            return RandomNumberService.this;
        }
    }

    public int getRandomNumber() {
        return mGenerator.nextInt();
    }
}

然后在你的 Activity 中，通过启动 Service 和绑定 Service 的方式获取随机数：

public class MainActivity extends AppCompatActivity {

    private boolean mBound = false;
    private RandomNumberService mService;

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

        Intent intent = new Intent(this, RandomNumberService.class);
        startService(intent);
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mBound) {
            unbindService(mConnection);
            mBound = false;
        }
    }

    private ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            RandomNumberService.LocalBinder binder = (RandomNumberService.LocalBinder) iBinder;
            mService = binder.getService();
            mBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            mBound = false;
        }
    };

    public void onGetRandomNumber(View view) {
        if (mBound) {
            int randomNumber = mService.getRandomNumber();
            Toast.makeText(this, "Random number: " + randomNumber, Toast.LENGTH_SHORT).show();
        }
    }
}

其中 `onGetRandomNumber` 是一个按钮的点击事件，当用户点击按钮时，会调用 `getRandomNumber` 方法获取随机数，并通过 Toast 显示出来。