从Android 2.2开始，加入了一个新的锁屏API位于android.app.admin.DevicePolicyManager包，DevicePolicyManager类的lockNow方法可以锁住屏幕，查看Android源代码发现其实是从IDevicePolicyManager实现的，整个AIDL接口调用代码为:

        

private final IDevicePolicyManager mService;mService = IDevicePolicyManager.Stub.asInterface(
ServiceManager.getService(Context.DEVICE_POLICY_SERVICE));if (mService != null) {
try {
mService.lockNow();
} catch (RemoteException e) {
Log.w(TAG, "Failed talking with device policy service", e);
}
}

这里Android123提示大家传统的方法加入<uses-permission android:name="android.permission.DISABLE_KEYGUARD"></uses-permission>权限，使用下面代码可以锁住键盘，但屏幕不行

KeyguardManager km = (KeyguardManager)getSystemService(Context.KEYGUARD_SERVICE); 
KeyguardLock kl= km.newKeyguardLock(KEYGUARD_SERVICE); 
kl.reenableKeyguard();