android 4.0 屏蔽home键实现

最近研究锁屏，按照常规的方法，常规方法如下

public void onAttachedToWindow(){         this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);            super.onAttachedToWindow(); }

但是这个方法到了4.0的系统上就失效了，按home照样会返回桌面。apktool了几个锁屏的软件之后发现其实现方法，即用WindowManager的addview方法将view加到窗口上，加上的时候将view的layoutparamas的type设为LayoutParams.TYPE_SYSTEM_ERROR，这个值sdk的解释为

public static final int TYPE_SYSTEM_ERROR Since: API Level 1 Window type: internal system error windows, appear on top of everything they can.

如果直接这样用会报错，还要在AndroidManifest.xml里面加上权限<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>，ok上完整代码，封装了一个类，其中Lock和hide方法实现锁屏和解锁。

public class LockLayer {private Activity mActivty;private WindowManager mWindowManager;private View mLockView;private LayoutParams mLockViewLayoutParams;public LockLayer(Activity act) {mActivty = act;init();}private void init(){mWindowManager = mActivty.getWindowManager();mLockViewLayoutParams = new LayoutParams();mLockViewLayoutParams.width = LayoutParams.MATCH_PARENT;mLockViewLayoutParams.height = LayoutParams.MATCH_PARENT;//实现关键mLockViewLayoutParams.type = LayoutParams.TYPE_SYSTEM_ERROR;//apktool value，这个值具体是哪个变量还请网友帮忙mLockViewLayoutParams.flags = 1280;        //1280=LayoutParams.FLAG_FULLSCREEN | LayoutParams.FLAG_LAYOUT_IN_SCREEN}public void lock() {if(mLockView!=null){mWindowManager.addView(mLockView, mLockViewLayoutParams);}}public void unlock() {if(mWindowManager!=null){mWindowManager.removeView(mLockView);}}public void setLockView(View v){mLockView = v;}}

使用方法如下

public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        View lock = View.inflate(this, R.layout.main, null);        LockLayer lockLayer = new LockLayer(this);        lockLayer.setLockView(lock);        lockLayer.lock();    }

ok,这时可以实现按home键不返回桌面的效果，其他的键需要用另外的代码实现，网上都有。这段代码只调用一次的时候没有问题，但是如果遇到多线程或者多次lock和hide就会有问题，修改如下，一是将LockLayer改为单例模式，二是在hide和lock的时候先判断状态。修改后代码如下

public class LockLayer {private Activity mActivty;private WindowManager mWindowManager;private View mLockView;private LayoutParams mLockViewLayoutParams;private static LockLayer mLockLayer;private boolean isLocked;public static synchronized LockLayer getInstance(Activity act){if(mLockLayer == null){mLockLayer = new LockLayer(act);}return mLockLayer;}private LockLayer(Activity act) {mActivty = act;init();}private void init(){isLocked = false;mWindowManager = mActivty.getWindowManager();mLockViewLayoutParams = new LayoutParams();mLockViewLayoutParams.width = LayoutParams.MATCH_PARENT;mLockViewLayoutParams.height = LayoutParams.MATCH_PARENT;//实现关键mLockViewLayoutParams.type = LayoutParams.TYPE_SYSTEM_ERROR;//apktool value，这个值具体是哪个变量还请网友帮忙mLockViewLayoutParams.flags = 1280;}public synchronized void lock() {if(mLockView!=null&&!isLocked){mWindowManager.addView(mLockView, mLockViewLayoutParams);}isLocked = true;}public synchronized void unlock() {if(mWindowManager!=null&&isLocked){mWindowManager.removeView(mLockView);}isLocked = false;}public synchronized void setLockView(View v){mLockView = v;}}

还有个问题是mLockViewLayoutParams.flags = 1280;1280这个值具体是哪个变量还不知道，有知道的留个言。

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