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Android组件创建DrawerLayout导航

时间:2022-07-24 10:16:12 | 栏目:Android代码 | 点击:

概述
本篇博客是对developer.android.com/上的Training课程的简单翻译,若是觉得翻译出来的理解有困难,请点击下方链接查看原文!
关于DrawerLayout的Training:http://developer.android.com/training/implementing-navigation/nav-drawer.html
关于DrawerLayout的API:http://developer.android.com/reference/android/support/v4/widget/DrawerLayout.html

创建抽屉布局

        创建一个抽屉布局必须得以DrawerLayout作为XML文件的根节点,记住,DrawerLayout引用的是Android.support.v4.DrawerLayout,然后在布局内部添加内容视图区域和一个或者两个抽屉视图区域,这里理解抽屉视图即为上面描述的菜单视图。例如下面一段布局中显示,在布局中添加一个FrameLayout作为内容区域(通常用来呈现Fragment),另外在下面定义了一个listView用来呈现抽屉菜单视图:

<android.support.v4.widget.DrawerLayout 
  xmlns:android="http://schemas.android.com/apk/res/android" 
  android:id="@+id/drawer_layout" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent"> 
  <!-- The main content view --> 
  <FrameLayout 
    android:id="@+id/content_frame" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" /> 
  <!-- The navigation drawer --> 
  <ListView android:id="@+id/left_drawer" 
    android:layout_width="240dp" 
    android:layout_height="match_parent" 
    android:layout_gravity="start" 
    android:choiceMode="singleChoice" 
    android:divider="@android:color/transparent" 
    android:dividerHeight="0dp" 
    android:background="#111"/> 
</android.support.v4.widget.DrawerLayout> 

这个布局文件示范了一些重要的布局特征.

初始化抽屉列表

        在你的Activity中, 第一件事就是初始化导航抽屉列表里面的元素, 你如何做取决于你的应用程序的内容,但一个导航抽屉通常包括一个ListView, 因此清单应该由一个Adapter填充(例如ArrayAdapter或SimpleCursorAdapter).
例如, 这里演示了如何用String array来初始化一个导航列表.

public class MainActivity extends Activity { 
  private String[] mPlanetTitles; 
  private DrawerLayout mDrawerLayout; 
  private ListView mDrawerList; 
  ... 
 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
 
    mPlanetTitles = getResources().getStringArray(R.array.planets_array); 
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
    mDrawerList = (ListView) findViewById(R.id.left_drawer); 
 
    // Set the adapter for the list view 
    mDrawerList.setAdapter(new ArrayAdapter<String>(this, 
        R.layout.drawer_list_item, mPlanetTitles)); 
    // Set the list's click listener 
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener()); 
 
    ... 
  } 
} 

这个代码调用setOnItemClickListener()去接收导航抽屉列表的点击事件. 下一节将展示如何实现这个接口,当用户选择一个Item时改变内容视图.

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 
  mDrawerList.setItemChecked(position, true); 
  setTitle(mPlanetTitles[position]); 
  mDrawerLayout.closeDrawer(mDrawerList); 
} 
 
@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) { 
        super.onDrawerClosed(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) { 
        super.onDrawerOpened(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:

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) { 
        super.onDrawerClosed(view); 
        getActionBar().setTitle(mTitle); 
      } 
 
      /** Called when a drawer has settled in a completely open state. */ 
      public void onDrawerOpened(View drawerView) { 
        super.onDrawerOpened(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); 
  } 
 
  ... 
} 

官方Demo:http://xiazai.jb51.net/201701/yuanma/NavigationDrawer(jb51.net).rar

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