监视屏幕开关,关闭和打开wifi

//屏幕监视类
public class ScreenObserver {
	private static String TAG = "ScreenObserver";
	private Context mContext;
	private ScreenBroadcastReceiver mScreenReceiver;
	private ScreenStateListener mScreenStateListener;
	private static Method mReflectScreenState;

	public ScreenObserver(Context context) {
		mContext = context;
		mScreenReceiver = new ScreenBroadcastReceiver();
		try {
			mReflectScreenState = PowerManager.class.getMethod("isScreenOn",
					new Class[] {});
		} catch (NoSuchMethodException nsme) {
			Log.d(TAG, "API < 7," + nsme);
		}
	}

	// screen状态广播接收者
	private class ScreenBroadcastReceiver extends BroadcastReceiver {
		private String action = null;

		@Override
		public void onReceive(Context context, Intent intent) {
			action = intent.getAction();
			if (Intent.ACTION_SCREEN_ON.equals(action)) {
				mScreenStateListener.onScreenOn();
			} else if (Intent.ACTION_SCREEN_OFF.equals(action)) {
				mScreenStateListener.onScreenOff();
			}
		}
	}

	// 请求screen状态更新
	public void requestScreenStateUpdate(ScreenStateListener listener) {
		mScreenStateListener = listener;
		startScreenBroadcastReceiver();

		firstGetScreenState();
	}

	// 第一次请求screen状态
	private void firstGetScreenState() {
		PowerManager manager = (PowerManager) mContext
				.getSystemService(Activity.POWER_SERVICE);
		if (isScreenOn(manager)) {
			if (mScreenStateListener != null) {
				mScreenStateListener.onScreenOn();
			}
		} else {
			if (mScreenStateListener != null) {
				mScreenStateListener.onScreenOff();
			}
		}
	}

	// 停止screen状态更新
	public void stopScreenStateUpdate() {
		mContext.unregisterReceiver(mScreenReceiver);
	}

	// 启动screen状态广播接收器
	private void startScreenBroadcastReceiver() {
		IntentFilter filter = new IntentFilter();
		filter.addAction(Intent.ACTION_SCREEN_ON);
		filter.addAction(Intent.ACTION_SCREEN_OFF);
		mContext.registerReceiver(mScreenReceiver, filter);
	}

	// screen是否打开状态
	private static boolean isScreenOn(PowerManager pm) {
		boolean screenState;
		try {
			screenState = (Boolean) mReflectScreenState.invoke(pm);
		} catch (Exception e) {
			screenState = false;
		}
		return screenState;
	}

	public interface ScreenStateListener {
		public void onScreenOn();

		public void onScreenOff();
	}
}



//调用的例子
public class MainActivity extends Activity {

	private ScreenObserver mScreenObserver;
	private WifiManager wifiManager;

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

		wifiManager = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);

		mScreenObserver = new ScreenObserver(this);
		mScreenObserver.requestScreenStateUpdate(new ScreenStateListener() {
			@Override
			public void onScreenOn() {
				doSomethingOnScreenOn();
			}

			@Override
			public void onScreenOff() {
				doSomethingOnScreenOff();
			}
		});
	}

	private void doSomethingOnScreenOn() {
		System.out.println("Screen is on");
		wifiManager.setWifiEnabled(true);

	}

	private void doSomethingOnScreenOff() {
		System.out.println("Screen is off");
		wifiManager.setWifiEnabled(false);
	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
		// 停止监听screen状态
		mScreenObserver.stopScreenStateUpdate();
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.activity_main, menu);
		return true;
	}

}