调用openOptionsMenu()菜单不显示

来源：互联网发布：centos无法输入密码编辑：程序博客网时间：2024/05/07 03:17

最近在实际开发中碰到按遥控器菜单键没有显示出菜单的情况，使用onKeyDown(int keyCode, KeyEvent event)监听：

    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {       if(keyCode == KeyEvent.KEYCODE_MENU){            Log.d("tag","keydown keycode:"+keyCode);            return true;        }        return super.onKeyDown(keyCode, event);    }output:keydown keycode:82

这里我们可以看到已经监听到了菜单点击事件，既然系统没有为我们执行显示菜单的代码，那我们可以自己手动的去调用：

    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {       if(keyCode == KeyEvent.KEYCODE_MENU){            //手动调用            super.openOptionsMenu();            return true;        }        return super.onKeyDown(keyCode, event);    }

可惜，实际情况是没什么效果…为什么了跟踪到openOptionsMenu()源码里面发现执行了Window下的抽象方法：

    /**     * Programmatically opens the options menu. If the options menu is already     * open, this method does nothing.     */    public void openOptionsMenu() {        if (mWindow.hasFeature(Window.FEATURE_OPTIONS_PANEL) &&                (mActionBar == null || !mActionBar.openOptionsMenu())) {            mWindow.openPanel(Window.FEATURE_OPTIONS_PANEL, null);        }    }

public abstract void openPanel(int featureId, KeyEvent event);

openPanel()方法最终被Window的子类PhoneWindow实现(window操作系统双击shift可搜索)

PhoneWindow 类直接搜索openPanel()方法可以看到：

 ... private void openPanel(final PanelFeatureState st, KeyEvent event) {             // Don't open an options panel for honeycomb apps on xlarge devices.        // (The app should be using an action bar for menu items.)        if (st.featureId == FEATURE_OPTIONS_PANEL) {            Context context = getContext();            Configuration config = context.getResources().getConfiguration();            boolean isXLarge = (config.screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) ==                    Configuration.SCREENLAYOUT_SIZE_XLARGE;            boolean isHoneycombApp = context.getApplicationInfo().targetSdkVersion >=                    android.os.Build.VERSION_CODES.HONEYCOMB;            if (isXLarge && isHoneycombApp) {                return;            }        }  ...

从上面这段源码中可以看到，通过判断当前设备的屏幕及sdk的版本，若屏幕是大屏并且当前sdk版本大于11，则不再做其他处理，直接return;

既然已经知道了原因，那么我们可以在调用openOptionsMenu()的时候做一些处理:

    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {        if(keyCode == KeyEvent.KEYCODE_MENU){            openOptionsMenu();            return true;        }        return super.onKeyDown(keyCode, event);    }  @Override    public void openOptionsMenu() {        Configuration config = getResources().getConfiguration();        //如果是大屏幕        if((config.screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK)> Configuration.SCREENLAYOUT_SIZE_LARGE) {            int originalScreenLayout = config.screenLayout;            config.screenLayout = Configuration.SCREENLAYOUT_SIZE_LARGE;            super.openOptionsMenu();            config.screenLayout = originalScreenLayout;        } else {            super.openOptionsMenu();        }    }

首先判断当前设备是否是大屏，如果是则先调整为较小屏调用菜单显示后在还原，到此菜单功能已经调整完成；最后在说源码中的一段注释：

 // Don't open an options panel for honeycomb apps on xlarge devices.// (The app should be using an action bar for menu items.)

这个是Android 源码里面的注释，意思也就是在说在大屏幕上推荐使用action bar来实现菜单功能

关于本文内容更多详细资料：

http://blog.csdn.net/mailyiran200101/article/details/9281177
http://stackoverflow.com/questions/9996333/openoptionsmenu-function-not-working-in-ics**

0 0