//屏蔽返回键的代码:
public boolean onKeyDown(int keyCode,KeyEvent event)
{
	switch(keyCode)
	{
		case KeyEvent.KEYCODE_HOME:return true;
		case KeyEvent.KEYCODE_BACK:return true;
		case KeyEvent.KEYCODE_CALL:return true;
		case KeyEvent.KEYCODE_SYM: return true;
		case KeyEvent.KEYCODE_VOLUME_DOWN: return true;
		case KeyEvent.KEYCODE_VOLUME_UP: return true;
		case KeyEvent.KEYCODE_STAR: return true;
	}
	return super.onKeyDown(keyCode, event);
}

//屏蔽home键的代码:
public void onAttachedToWindow() 
{
	this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
	super.onAttachedToWindow();
}