android4.0屏蔽home键

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

Java代码 

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。
Java代码 

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; 
    } 
    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
Java代码 

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
Java代码 

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。