java以编程方式在Android中锁定手机？

Question

我试图锁定设备，并试图使用以下代码启用它，但它不起作用。我还取得了以下两个许可证，没有显示手机已锁定。。。我还试图再次解锁它

public class LockPhoneActivity extends Activity implements OnClickListener {
    /** Called when the activity is first created. */

    Button lock, unlock;

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

        lock = (Button) findViewById(R.id.button1);
        unlock = (Button) findViewById(R.id.button2);

        lock.setOnClickListener(this);
        unlock.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub

        switch (v.getId()) {

        case R.id.button1:

            KeyguardManager mgr = (KeyguardManager) getSystemService(Activity.KEYGUARD_SERVICE);
            KeyguardLock lock = mgr.newKeyguardLock(KEYGUARD_SERVICE);
            lock.reenableKeyguard();

            Toast.makeText(getApplicationContext(), "Locked", Toast.LENGTH_LONG)
                    .show();

            break;

        case R.id.button2:

            KeyguardManager mgr1 = (KeyguardManager) getSystemService(Activity.KEYGUARD_SERVICE);
            KeyguardLock lock1 = mgr1.newKeyguardLock(KEYGUARD_SERVICE);

            lock1.disableKeyguard();

            break;
        }
    }
}

我还获得了以下许可

<uses-permission 安卓:name="安卓.permission.WAKE_LOCK"/>
<uses-permission 安卓:name="安卓.permission.DISABLE_KEYGUARD"/>