处理导航点击事件

当用户选择了抽屉列表里面的一个Item时, 系统调用onItemClickListener上的onItemClick(), 给setOnItemClickListener().

你在onItemClick()方法里面做什么, 取决于你的app实现的结构. 在下面的例子中, 选择每一个Item都会在主要内容的布局中插入一个不同的Fragment.

private class DrawerItemClickListener implements ListView.OnItemClickListener {      @Override      public void onItemClick(AdapterView parent, View view, int position, long id) {          selectItem(position);      }  }    /** Swaps fragments in the main content view */  private void selectItem(int position) {      // Create a new fragment and specify the planet to show based on position      Fragment fragment = new PlanetFragment();      Bundle args = new Bundle();      args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);      fragment.setArguments(args);        // Insert the fragment by replacing any existing fragment      FragmentManager fragmentManager = getFragmentManager();      fragmentManager.beginTransaction()                     .replace(R.id.content_frame, fragment)                     .commit();        // Highlight the selected item, update the title, and close the drawer      mDrawer.setItemChecked(position, true);      setTitle(mPlanetTitles[position]);      mDrawerLayout.closeDrawer(mDrawer);  }    @Override  public void setTitle(CharSequence title) {      mTitle = title;      getActionBar().setTitle(mTitle);  }

监听打开和关闭事件

侦听抽屉打开和关闭事件,调用你的DrawerLayout setDrawerListener(), 并将其传递给DrawerLayout.DrawerListener的实现. 这个接口提供了回调抽屉事件, 如onDrawerOpened()和onDrawerClosed ()。

然而, 相对于实现DrawerLayout.DrawerListener, 如果你的Activity包括工具栏, 可以代替继承ActionBarDrawerToggle类. ActionBarDrawerToggle实现了DrawerLayout.DrawerListener. 所以你仍然可以覆盖这些回调, 但它也有助于正确的交互行为, 在工具栏的图标和导航抽屉之间(下一节将进一步讨论)。

就像在导航抽屉设计指南一样,当抽屉是可见的时候, 你应该修改工具栏的内容, 如改变标题和删除操作Item. 下面的代码用ActionBarDrawerToggle类的一个实例, 显示了如何重写DrawerLayout.DrawerListener的回调方法:

public class MainActivity extends Activity {      private DrawerLayout mDrawerLayout;      private ActionBarDrawerToggle mDrawerToggle;      private CharSequence mDrawerTitle;      private CharSequence mTitle;      ...        @Override      public void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main);          ...            mTitle = mDrawerTitle = getTitle();          mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);          mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,                  R.drawable.ic_drawer, R.string.drawer_open, R.string.drawer_close) {                /** Called when a drawer has settled in a completely closed state. */              public void onDrawerClosed(View view) {                  getActionBar().setTitle(mTitle);                  invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()              }                /** Called when a drawer has settled in a completely open state. */              public void onDrawerOpened(View drawerView) {                  getActionBar().setTitle(mDrawerTitle);                  invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()              }          };            // Set the drawer toggle as the DrawerListener          mDrawerLayout.setDrawerListener(mDrawerToggle);      }        /* Called whenever we call invalidateOptionsMenu() */      @Override      public boolean onPrepareOptionsMenu(Menu menu) {          // If the nav drawer is open, hide action items related to the content view          boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);          menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);          return super.onPrepareOptionsMenu(menu);      }  }

下一节描述ActionBarDrawerToggle构造函数参数和其他所需的步骤来设置它来处理工具栏的图标.

打开关闭应用图标

用户可以打开和关闭导航抽屉, 通过手指从屏幕左侧的边缘滑动, 但如果你使用工具栏, 你应该也能允许用户打开和关闭它, 通过触摸应用程序图标. 应用程序图标也可以显示一个特殊的图标关于导航抽屉的状态. 你可以实现所有这些行为通过使用ActionBarDrawerToggle, 如前一节所示。

让ActionBarDrawerToggle工作, 创建一个它的实例用它的构造方法, 这就需要以下参数:

• 持有抽屉的Activity.
• DrawerLayout对象.
• 一个Drawable资源作为抽屉指示器.
• 字符串资源描述"打开抽屉"动作.
• 字符串资源描述"关闭抽屉"动作.

然后, 无论你是否已经创建了一个ActionBarDrawerToggle的子类作为你的抽屉的Listener, 你需要在几个Activity生命周期的地方, 调用你的ActionBarDrawerToggle:

public class MainActivity extends Activity {      private DrawerLayout mDrawerLayout;      private ActionBarDrawerToggle mDrawerToggle;      ...        public void onCreate(Bundle savedInstanceState) {          ...            mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);          mDrawerToggle = new ActionBarDrawerToggle(                  this,                  /* host Activity */                  mDrawerLayout,         /* DrawerLayout object */                  R.drawable.ic_drawer,  /* nav drawer icon to replace 'Up' caret */                  R.string.drawer_open,  /* "open drawer" description */                  R.string.drawer_close  /* "close drawer" description */                  ) {                /** Called when a drawer has settled in a completely closed state. */              public void onDrawerClosed(View view) {                  getActionBar().setTitle(mTitle);              }                /** Called when a drawer has settled in a completely open state. */              public void onDrawerOpened(View drawerView) {                  getActionBar().setTitle(mDrawerTitle);              }          };            // Set the drawer toggle as the DrawerListener          mDrawerLayout.setDrawerListener(mDrawerToggle);            getActionBar().setDisplayHomeAsUpEnabled(true);          getActionBar().setHomeButtonEnabled(true);      }        @Override      protected void onPostCreate(Bundle savedInstanceState) {          super.onPostCreate(savedInstanceState);          // Sync the toggle state after onRestoreInstanceState has occurred.          mDrawerToggle.syncState();      }        @Override      public void onConfigurationChanged(Configuration newConfig) {          super.onConfigurationChanged(newConfig);          mDrawerToggle.onConfigurationChanged(newConfig);      }        @Override      public boolean onOptionsItemSelected(MenuItem item) {          // Pass the event to ActionBarDrawerToggle, if it returns          // true, then it has handled the app icon touch event          if (mDrawerToggle.onOptionsItemSelected(item)) {            return true;          }          // Handle your other action bar items...            return super.onOptionsItemSelected(item);      }        ...  }