Navigation Drawer 的初了解以及 ActionBar 自定义视图(标题居中)

整个示例都是改造自 Google Android Training 中的 NavigationDrawer 示例(http://developer.android.com/training/implementing-navigation/nav-drawer.html)

因为我需要使用自定义的 ActionBar，而ActionBarDrawerToggle 只能通过 ActionBar 中的 Action Menu 进行触发，且需要提供一个indicator图片，而不支持自定义按钮的触发（如下代码）；

public boolean onOptionsItemSelected(MenuItem item) {
    if (item != null && item.getItemId() == ID_HOME && mDrawerIndicatorEnabled) {
        if (mDrawerLayout.isDrawerVisible(GravityCompat.START)) {
            mDrawerLayout.closeDrawer(GravityCompat.START);
        } else {
            mDrawerLayout.openDrawer(GravityCompat.START);
        }
        return true;
    }
    return false;
}

因此考虑参考 ActionBarDrawerToggle 重写自己的 MabDrawerToggle，然后去掉 onOptionsItemSelected 方式来触发 drawer，新增了一个 switchDrawer 方法，如下：

public void switchDrawer()
{
    if (mDrawerLayout.isDrawerVisible(GravityCompat.START))
    {
        mDrawerLayout.closeDrawer(GravityCompat.START);
    }
    else
    {
        mDrawerLayout.openDrawer(GravityCompat.START);
    }
}

下面看一下 ActionBar 自定义 View 中标题居中的问题，折腾了好久，最后采用 FrameLayout 方式解决的，如下 action_bar_title.xml：

在 onCreate 中实现如下：

protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mTitle = getTitle();
    mPlanetTitles = getResources().getStringArray(R.array.planets_array);
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerList = (ListView) findViewById(R.id.left_drawer);
    // set a custom shadow that overlays the main content when the drawer opens
    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
    mDrawerList.setAdapter(new ArrayAdapter(this,
            R.layout.drawer_list_item, mPlanetTitles));
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
    ActionBar.LayoutParams lp = new ActionBar.LayoutParams(
            ActionBar.LayoutParams.MATCH_PARENT,
            ActionBar.LayoutParams.MATCH_PARENT,
            Gravity.CENTER);
    View viewTitleBar = getLayoutInflater().inflate(R.layout.action_bar_title, null);
    getActionBar().setCustomView(viewTitleBar, lp);
    getActionBar().setDisplayShowHomeEnabled(false);
    getActionBar().setDisplayShowTitleEnabled(false);
    getActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
    getActionBar().setDisplayShowCustomEnabled(true);
    tvTitle = (TextView) getActionBar().getCustomView().findViewById(android.R.id.title);
    ImageButton ibtnNav = (ImageButton) getActionBar().getCustomView().findViewById(R.id.left_btn);
    ibtnNav.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mDrawerToggle.switchDrawer();
        }
    });
    // MabDrawerToggle ties together the the proper interactions
    // between the sliding drawer and the action bar app icon
    mDrawerToggle = new MabDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout,         /* DrawerLayout object */
            R.drawable.ic_drawer,  /* nav drawer p_w_picpath to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description for accessibility */
            R.string.drawer_close  /* "close drawer" description for accessibility */
            );
    mDrawerLayout.setDrawerListener(mDrawerToggle);
    if (savedInstanceState == null)
    {
        selectItem(0);
    }
}

下面为两张运行效果图：

选择 Navigation 列表中的项后，切换 Fragment 以及 标题：