android 安卓 捕获屏幕变黑，变亮，解锁事件

package com.lock.muskmelon;

import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

public class Lock8secondActivity extends Activity {

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

final String TAG = null;

final IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_USER_PRESENT);

final BroadcastReceiver mBatInfoReceiver = new BroadcastReceiver() {
@Override
public void onReceive(final Context context, final Intent intent) {

String action = intent.getAction();

if(Intent.ACTION_SCREEN_ON.equals(action))
{
Log.d(TAG, "screen is on...");

}

else if(Intent.ACTION_SCREEN_OFF.equals(action))
{
Log.d(TAG, "screen is off...");
}

else if(Intent.ACTION_USER_PRESENT.equals(action))
{
Log.d(TAG, "screen is unlock...");
}

}
};

registerReceiver(mBatInfoReceiver, filter);

}

}