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 這里使用的是android.provider.Settings.System.WIFI_SLEEP_POLICY *  而不是Settings.System.WIFI_SLEEP_POLICY!!!!!!!!!!!!!!!!!!!!!!! *   * 2 權限<uses-permission android:name="android.permission.WRITE_SETTINGS"/> *  * 3 在實際項目中,這么強制性地設置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,待我們的邏輯完成后再還原回去為好. */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("---> 修改后的Wifi休眠策略值 WIFI_SLEEP_POLICY="+wifiSleepPolicy); } }<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" > <TextView  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="@string/hello_world" /></RelativeLayout>