Android官方终于支持 Navigation Drawer(导航抽屉)模式

Posted 2020-09-24 youseiraws

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Android官方终于支持 Navigation Drawer(导航抽屉)模式相关的知识，希望对你有一定的参考价值。

在2013 google IO当天，android团的更新了Support库，新版本（V13）的Support库中新加入了几个比较重要的功能。

添加 DrawerLayout 控件，支持创建 Navigation Drawer模式。可以设置从左边划出菜单或者右边，也可以左右菜单同时存在。
添加 SlidingPaneLayout 控件来支持各种屏幕上的摘要、详情界面模式。比如 Gmail邮件列表和单个邮件详情界面。当在手机上显示的时候，邮件列表和详情界面分别为两个界面；当在平板上显示的时候，则为一个界面。
添加 ActionBarDrawerToggle 工具类，方便把 DrawerLayout 和 ActionBar 功能结合起来。

下面来介绍下如何使用DrawerLayout 控件来实现抽屉菜单

创建Drawer Layout

在需要抽屉菜单的界面，用DrawerLayout 作为界面根控件。在DrawerLayout里面第一个View为当前界面主内容；第二个和第三个View为抽屉菜单内容。如果当前界面只需要一个抽屉菜单，则第三个View可以省略。

下面的例子中DrawerLayout里面包含两个View，第一个FrameLayout中是当前界面主要内容显示区域；第二个ListView为抽屉菜单内容。

<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>

<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">

<FrameLayout

android:id="@+id/content_frame"

android:layout_width="match_parent"

android:layout_height="match_parent"/>

<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>

上面的代码中有如下几点需要注意：

显示界面主要内容的View (上面的 FrameLayout ) 必须为DrawerLayout的第一个子View， 原因在于 XML 布局文件中的View顺序为Android系统中的 z-ordering顺序，而抽屉必须出现在内容之上。
显示界面内容的View宽度和高度设置为和父View一样，原因在于当抽屉菜单不可见的时候，界面内容代表整个界面UI。
抽屉菜单 (上面的 ListView) 必须使用android:layout_gravity属性设置水平的 gravity值 .如果要支持 right-to-left (RTL，从右向左阅读)语言用 "start" 代替 "left" (当在 RTL语言运行时候，菜单出现在右侧)。
抽屉菜单的宽度为 dp 单位而高度和父View一样。抽屉菜单的宽度应该不超过320dp，这样用户可以在菜单打开的时候看到部分内容界面。

初始化抽屉菜单

在您的Activity中需要先初始化抽屉菜单内容，根据您的应用需要抽屉菜单的内容可能不是ListView。

在上面的示例中，我们需要给菜单的ListView设置一个Adapter来提供数据。如下所示：

public class MainActivity extends Activity {
    private String[] mPlanetTitles;
    private ListView mDrawerList;
    ...

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mPlanetTitles = getResources().getStringArray(R.array.planets_array);
        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());

        ...
    }
}

publicclassMainActivityextendsActivity{

privateString[]mPlanetTitles;

privateListView mDrawerList;

...

@Override

publicvoidonCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mPlanetTitles=getResources().getStringArray(R.array.planets_array);

mDrawerList=(ListView)findViewById(R.id.left_drawer);

// Set the adapter for the list view

mDrawerList.setAdapter(newArrayAdapter<String>(this,

R.layout.drawer_list_item,mPlanetTitles));

// Set the list‘s click listener

mDrawerList.setOnItemClickListener(newDrawerItemClickListener());

...

}

上面的代码调用了 setOnItemClickListener() 函数来接受菜单条目点击事件。下面会介绍如何更加点击菜单来显示主界面内容。

处理菜单点击事件

当用户选择菜单List中的条目时，系统会调用 OnItemClickListener的 onItemClick()函数。

根据您的应用需要onItemClick函数的实现方式可能不同。下面的示例中，选择菜单条目会在程序主界面中插入不同的 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);
}

privateclassDrawerItemClickListener implementsListView.OnItemClickListener{

@Override

publicvoidonItemClick(AdapterView parent,View view,intposition,longid){

selectItem(position);

}

/** Swaps fragments in the main content view */

privatevoidselectItem(intposition){

// Create a new fragment and specify the planet to show based on position

Fragment fragment=newPlanetFragment();

Bundle args=newBundle();

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

publicvoidsetTitle(CharSequence title){

mTitle=title;

getActionBar().setTitle(mTitle);

}

监听菜单打开关闭事件

如果需要监听菜单打开关闭事件，则需要调用 DrawerLayout类的 setDrawerListener() 函数，参数为 DrawerLayout.DrawerListener接口的实现。该接口提供了菜单打开关闭等事件的回调函数，例如 onDrawerOpened() 和onDrawerClosed().

如果您的Activity使用了 action bar，则您可以使用Support库提供的 ActionBarDrawerToggle 类，该类实现了 DrawerLayout.DrawerListener接口，并且您还可以根据需要重写相关的函数。该类实现了菜单和Action bar相关的操作。

根据在 Navigation Drawer 设计指南中的介绍，当菜单显示的时候您应该根据情况隐藏ActionBar上的功能菜单并且修改ActionBar的标题。下面的代码演示了如何重写 ActionBarDrawerToggle 类的相关函数来实现该功能。

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);
    }
}

publicclassMainActivityextendsActivity{

privateDrawerLayout mDrawerLayout;

privateActionBarDrawerToggle mDrawerToggle;

privateCharSequence mDrawerTitle;

privateCharSequence mTitle;

...

@Override

publicvoidonCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

...

mTitle=mDrawerTitle=getTitle();

mDrawerLayout=(DrawerLayout)findViewById(R.id.drawer_layout);

mDrawerToggle=newActionBarDrawerToggle(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. */

publicvoidonDrawerClosed(View view){

getActionBar().setTitle(mTitle);

invalidateOptionsMenu();// creates call to onPrepareOptionsMenu()

}

/** Called when a drawer has settled in a completely open state. */

publicvoidonDrawerOpened(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

publicbooleanonPrepareOptionsMenu(Menu menu){

// If the nav drawer is open, hide action items related to the content view

booleandrawerOpen=mDrawerLayout.isDrawerOpen(mDrawerList);

menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);

returnsuper.onPrepareOptionsMenu(menu);

}

最后来介绍下 ActionBarDrawerToggle 类的功能。

应用图标指示抽屉开关

用户可以从屏幕边缘滑动来打开抽屉菜单，如果您使用了 action bar，应该让用户通过点击应用图标也可以打开抽屉菜单。并且应用图标也应该使用一个特殊的图标来指示抽屉菜单。您可以使用 ActionBarDrawerToggle 类来实现这些功能。

要使用 ActionBarDrawerToggle ，先通过其构造函数来创建该对象，构造函数需要如下参数：

显示抽屉的 Activity 对象
DrawerLayout 对象
一个用来指示抽屉的 drawable资源
一个用来描述打开抽屉的文本 (用于支持可访问性)。
一个用来描述关闭抽屉的文本(用于支持可访问性).

无论你是否继承 ActionBarDrawerToggle 来实现抽屉监听器，您都需要在Activity的生命周期函数中调用ActionBarDrawerToggle 的一些函数。

如下所示：

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, 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);
            }

            /** 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.
        <span style="color: #ff0000;">mDrawerToggle.syncState();</span>
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        <span style="color: #ff0000;">mDrawerToggle.onConfigurationChanged(newConfig);</span>
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Pass the event to ActionBarDrawerToggle, if it returns
        // true, then it has handled the app icon touch event
        <span style="color: #ff0000;">if (mDrawerToggle.onOptionsItemSelected(item)) {</span>
<span style="color: #ff0000;"> return true;</span>
<span style="color: #ff0000;"> }</span>
        // Handle your other action bar items...

        return super.onOptionsItemSelected(item);
    }

    ...
}

publicclassMainActivityextendsActivity{

privateDrawerLayout mDrawerLayout;

privateActionBarDrawerToggle mDrawerToggle;

...

publicvoidonCreate(Bundle savedInstanceState){

...

mDrawerLayout=(DrawerLayout)findViewById(R.id.drawer_layout);

mDrawerToggle=newActionBarDrawerToggle(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. */

publicvoidonDrawerClosed(View view){

getActionBar().setTitle(mTitle);

}

/** Called when a drawer has settled in a completely open state. */

publicvoidonDrawerOpened(View drawerView){

getActionBar().setTitle(mDrawerTitle);

}

};

// Set the drawer toggle as the DrawerListener

mDrawerLayout.setDrawerListener(mDrawerToggle);

getActionBar().setDisplayHomeAsUpEnabled(true);

getActionBar().setHomeButtonEnabled(true);

}

@Override

protectedvoidonPostCreate(Bundle savedInstanceState){

super.onPostCreate(savedInstanceState);

// Sync the toggle state after onRestoreInstanceState has occurred.

mDrawerToggle.syncState();

}

@Override

publicvoidonConfigurationChanged(Configuration newConfig){

super.onConfigurationChanged(newConfig);

mDrawerToggle.onConfigurationChanged(newConfig);

}

@Override

publicbooleanonOptionsItemSelected(MenuItem item){

// Pass the event to ActionBarDrawerToggle, if it returns

// true, then it has handled the app icon touch event

if(mDrawerToggle.onOptionsItemSelected(item)){

returntrue;

}

// Handle your other action bar items...

returnsuper.onOptionsItemSelected(item);

}

...

}

猛击我下载示例项目代码。

以上是关于Android官方终于支持 Navigation Drawer(导航抽屉)模式的主要内容，如果未能解决你的问题，请参考以下文章

Android：Navigation使用safe args插件传递参数

Android Jetpack之Navigation源码分析

Android终于要推出Google官方的二维码扫描库了？