MediaRecorder & MediaPlayer ~ 個人錄音(五)

以Service來紀錄各種state,

在 Android 有四種 application components:

1. Activities

2. Services

3. Content providers

4. Intent

在 Android 應用程式裡，有一種沒有 UI 的類別（android.app.Service），稱之為 Service。

Service (import android.app.Service) 是一個 background process（背景程序），不像 Activity 有著介面可以讓使用者操作, Service 的生命周期都是比較長，可以在背景長駐執行一些不中斷的程式, 像是背景錄音, 播放音樂, 定期自動更新

PersonRecordService.java

public class PersonRecordService extends Service{
    static final int IDLE_STATE = 0;
    static final int RECORDING_STATE = 1;
    static final int PLAYING_STATE = 2;
    static final int PAUSE_STATE = 3;
    int mState = 0;

    public interface OnStateChangedListener {
        public void onStateChanged(int state);
        public void onError(int error);
    }

    OnStateChangedListener mOnStateChangedListener = null;

    public void setOnStateChangedListener(OnStateChangedListener listener) {
        mOnStateChangedListener = listener;
    }

    private void setState(int state) {
        mState = state;
        signalStateChanged(mState);
    }
    private void signalStateChanged(int state) {
        if (mOnStateChangedListener != null)
            mOnStateChangedListener.onStateChanged(state);
    }
}

PersonRecordActivity.java

public class PersonRecordActivity extends Activity implements PersonRecordService.OnStateChangedListener {

    PersonRecordService personRecordService = new PersonRecordService();
    personRecordService.setOnStateChangedListener(this);
    WakeLock mWakeLock;
    public void onCreate(Bundle savedInstanceState) {
        PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
        mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "PersonRecord");

        @Override
        public void onStateChanged(int state) {
            if (state == PersonRecordService.PLAYING_STATE || state == PersonRecordService.RECORDING_STATE) {
                // 背景恆亮
                mWakeLock.acquire(); 
            } else {
                if (mWakeLock.isHeld())
                    // 取消背景恆亮
                    mWakeLock.release();
            }
            updateUi();
        }

        @Override
        public void onError(int error) {
  
        }
    }
}

當手機在螢幕醒著的狀態, 長時間不觸碰面板則螢幕會自動暗掉, 進而進入待機狀態,

為防止手機進入待機狀態, 則需使用到 PowerManage 這個功能

AndroidManifest.xml