設置Android設備在睡眠期間始終保持WLAN開啟的代碼實現

package cc.ab;

import android.os.Bundle;
import android.provider.Settings;
import android.app.Activity;
/**
 * Demo描述:
 * 設置設備在睡眠期間始終保持WLAN開啟.
 * 
 * 參考資料:
 * 1 http://stackoverflow.com/questions/8652031/how-to-modify-wi-fi-sleep-policy-programmatically/8655070#8655070
 * 2 http://blog.csdn.net/mrlixirong/article/details/24938637
 *   Thank you very much
 *   
 *  注意事項:
 *  1 這裡使用的是android.provider.Settings.System.WIFI_SLEEP_POLICY
 *    而不是Settings.System.WIFI_SLEEP_POLICY!!!!!!!!!!!!!!!!!!!!!!!
 *    
 *  2 權限
 *  
 *  3 在實際項目中,這麼強制性地設置WIFI在休眠時永不斷開有些粗魯了.
 *    可以先記錄下WIFI原本的策略,待我們的邏輯完成後再還原回去為好.
 */
public class MainActivity extends Activity {

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

	private void setWifiNeverSleep(){
		int wifiSleepPolicy=0;
		wifiSleepPolicy=Settings.System.getInt(getContentResolver(),
				                               android.provider.Settings.System.WIFI_SLEEP_POLICY,
				                               Settings.System.WIFI_SLEEP_POLICY_DEFAULT);
		System.out.println("---> 修改前的Wifi休眠策略值 WIFI_SLEEP_POLICY="+wifiSleepPolicy);
		
		
		Settings.System.putInt(getContentResolver(),
				               android.provider.Settings.System.WIFI_SLEEP_POLICY,
				               Settings.System.WIFI_SLEEP_POLICY_NEVER);
		
		
		wifiSleepPolicy=Settings.System.getInt(getContentResolver(),
                android.provider.Settings.System.WIFI_SLEEP_POLICY,
                Settings.System.WIFI_SLEEP_POLICY_DEFAULT);
        System.out.println("---> 修改後的Wifi休眠策略值 WIFI_SLEEP_POLICY="+wifiSleepPolicy);
	}
	
}

main.xml如下: