[Android] dialog,activity 屏蔽Home键详解

 相信在Android应用上，很多时候逻辑是需要屏蔽Home键的，但这个用户体验是否需要，就看各位的需求了。 
    一般的方法屏蔽Home键，大家一定看过不少文章了。我总结一下，先说一下一般情况下Activity的屏蔽按键和Home键吧。 
屏蔽其他键，重写onKeyDown 

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    Log.i(TAG,"keycode="+keyCode + "   isBan="+isBan);
    switch (keyCode) {
        case KeyEvent.KEYCODE_BACK:
        Log.i(TAG,"KEYCODE_BACK");
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

大家会发现，这里屏蔽Home键是捕捉不到的，因为大家的权限一般是User所以是无效的。 
而其实android处理Home键等系统级按键是有一定的处理的。 

引用

看看源码是怎样处理的 \frameworks\policies\base\phone\com\android\internal\policy\impl\PhoneWindowManager.java #1092

// First we always handle the home key here, so applications
// can never break it, although if keyguard is on, we do let
// it handle it, because that gives us the correct 5 second
// timeout.
if (code == KeyEvent.KEYCODE_HOME) {

    // If a system window has focus, then it doesn't make sense
    // right now to interact with applications.
    WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;
    if (attrs != null) {
        final int type = attrs.type;
        if (type == WindowManager.LayoutParams.TYPE_KEYGUARD
           || type == WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG) {
            // the "app" is keyguard, so give it the key
            return false;
        }
        final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;
        for (int i=0; i
            if (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {
                // don't do anything, but also don't pass it to the app
                return true;
            }
        }
    }

通过源码，我们不难发现两个的参数 WindowManager.LayoutParams.TYPE_KEYGUARD和 
WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG 
借鉴于此，重写onAttachedToWindow，以实现屏蔽Home键

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

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轮到dialog了，如果在Activity弹出dialog，在Activity设置以上2个方法是没办法屏蔽的。 
其实，原理是一样的，只是地方不一样而已。 

final Dialog dialog = new Dialog(this);
dialog.setContentView(R.layout.mydailog);
dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
dialog.show();

dialog.setOnKeyListener(new android.content.DialogInterface.OnKeyListener(){
    @Override
    public boolean onKey(DialogInterface dialog, int keyCode,KeyEvent event) {
        switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
            Log.i(TAG,"KEYCODE_BACK");
            return true;
        }
        return false;
    }
});

这样运行后，出错如下： 

10-18 13:27:06.380: ERROR/AndroidRuntime(4684): Caused by: android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRoot$W@2b046d68 -- permission denied for this window type

其实，只需要把dialog.getWindow().setType的位置放在show后面就可以了 

dialog.show();
dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);

这么，就完成了Back键的屏蔽 和Home键盘的屏蔽了！ 

总结： 
1:)在以上用WindowManager.LayoutParams.TYPE_KEYGUARD的地方改用 
WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG 效果一样。至于两者的具体差别，得以后再研究研究。 

2:)其实，在源码里是这样调用的。

final AlertDialog dialog = new AlertDialog.Builder(mContext)
    .setTitle(null)
    .setMessage(message)
    .setNeutralButton(R.string.ok, null)
    .create();
dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
dialog.show();

    但我们如果这样调用就会出现之前的那个error：permission denied for this window type 这就显而易见了吧~~ 

3:)ProgressDialog 默认屏蔽 Back键，Dialog，AlertDialog则需setOnKeyListener 

4:)其实屏蔽Home键，在页面的某个地方，例如一个Button的onClick里，去设置setType就可以了,如： 

button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
    }
});

但前提是重载Activity的onAttachedToWindow()，哪怕只是一个空实现，然后返回父类方法。 

@Override
public void onAttachedToWindow() {
    super.onAttachedToWindow();
}

5:)其实它们，都是常用的~

switch (keyCode) {
    case KeyEvent.KEYCODE_HOME:
        Log.i(TAG,"KEYCODE_HOME");
        return true;
    case KeyEvent.KEYCODE_BACK:
        Log.i(TAG,"KEYCODE_BACK");
        return true;
    case KeyEvent.KEYCODE_CALL:
        Log.i(TAG,"KEYCODE_CALL");
        return true;
    case KeyEvent.KEYCODE_SYM:
        Log.i(TAG,"KEYCODE_SYM");
        return true;
    case KeyEvent.KEYCODE_VOLUME_DOWN:
        Log.i(TAG,"KEYCODE_VOLUME_DOWN");
        return true;
    case KeyEvent.KEYCODE_VOLUME_UP:
        Log.i(TAG,"KEYCODE_VOLUME_UP");
        return true;
    case KeyEvent.KEYCODE_STAR:
        Log.i(TAG,"KEYCODE_STAR");
        return true;
}

希望大家看到这个文章能觉得有用，谢谢已阅者！