当点击back键时执行home键的操作，保留之前的操作记录

 //当点击back键的时候让它执行home键    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {        switch (keyCode) {            case KeyEvent.KEYCODE_BACK:                Intent intent = new Intent();                intent.setAction("android.intent.action.MAIN");                intent.addCategory("android.intent.category.HOME");                startActivity(intent);                break;        }        return false;    }