手把手教你打造一个Material Design风格的App(三)

——接上文。

3.2添加抽屉导航

添加导航抽屉跟Android 5.0之前是一样的，只是以前我们使用ListView来作为菜单容器，现在我们则使用Material Design风格的RecyclerView。

（14）在你工程的java文件夹中，创建3个名为activity、adapter、model的包，将MainActivity.java移到activtiy包中，这样做使得你的代码可以很好地组织和管理。

（15）打开位于app模块下的build.gradle文件并添加如下依赖。添加完依赖之后，点击Build-->Rebuild Project下载所需要的类库。

build.gradle
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile 'com.android.support:recyclerview-v7:21.0.+'
}

（16）在model包里，创建名为NavDrawerItem.java的类，然后添加以下代码。这个模型类是一个简单的POJO（Plain Oridinary Java Object即简单的java对象）类，它定义了导航抽屉的菜单项。

NavDrawerItem.java
package androidhive.info.materialdesign.model;

public class NavDrawerItem {
    private boolean showNotify;
    private String title;

    public NavDrawerItem() {

    }

    public NavDrawerItem(boolean showNotify, String title) {
        this.showNotify = showNotify;
        this.title = title;
    }

    public boolean isShowNotify() {
        return showNotify;
    }

    public void setShowNotify(boolean showNotify) {
        this.showNotify = showNotify;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

（17）在res-->layout下，创建一个名为nav_drawer_row.xml的文件并添加如下代码。这个布局渲染了导航抽屉菜单的每一行，如果你想自定义抽屉菜单项，你需要修改这个布局文件。在这个例子中，它仅包含一个TextView。

nav_drawer_row.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clickable="true">

    <TextView
        android:id="@+id/title"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="30dp"
        android:paddingTop="10dp"
        android:paddingBottom="10dp"
        android:textSize="15dp"
        android:textStyle="bold" />

</RelativeLayout>

（18）下载个人资料图标并将它放入drawable文件夹，这一步是可选的，但是这个图标会在导航抽屉的头部用到。

（19）创建另一个名为fragment_navigation_drawer.xml的布局文件并添加如下代码。这个布局文件渲染了整个导航抽屉的视图，这个布局包括一个显示个人信息的头部和一个显示列表的RecycleView。

fragment_navigation_drawer.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white">

    <RelativeLayout
        android:id="@+id/nav_header_container"
        android:layout_width="match_parent"
        android:layout_height="140dp"
        android:layout_alignParentTop="true"
        android:background="@color/colorPrimary">

        <ImageView
            android:layout_width="70dp"
            android:layout_height="70dp"
            android:src="@drawable/ic_profile"
            android:scaleType="fitCenter"
            android:layout_centerInParent="true" />

    </RelativeLayout>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/drawerList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/nav_header_container"
        android:layout_marginTop="15dp" />

</RelativeLayout>

（20）因为RecycleView是自定义的，我们还需要一个adapter来渲染自定义的xml布局，所以在adapter包下面，创建一个名为NavgationDrawerAdapter.java的类并添加如下代码。这个适配器类inflate了nav_drawer_row.xml并渲染了RecycleView抽屉菜单。

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.Collections;
import java.util.List;

/**
 * Created by Ravi Tamada on 12-03-2015.
 */
public class NavigationDrawerAdapter extends RecyclerView.Adapter<NavigationDrawerAdapter.MyViewHolder> {
    List<NavDrawerItem> data = Collections.emptyList();
    private LayoutInflater inflater;
    private Context context;

    public NavigationDrawerAdapter(Context context, List<NavDrawerItem> data) {
        this.context = context;
        inflater = LayoutInflater.from(context);
        this.data = data;
    }

    public void delete(int position) {
        data.remove(position);
        notifyItemRemoved(position);
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.nav_drawer_row, parent, false);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        NavDrawerItem current = data.get(position);
        holder.title.setText(current.getTitle());
    }

    @Override
    public int getItemCount() {
        return data.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView title;

        public MyViewHolder(View itemView) {
            super(itemView);
            title = (TextView) itemView.findViewById(R.id.title);
        }
    }
}

（21）在activity包下，创建一个名为FragmentDrawer.java的Fragment。在Android Studio里面，按以下操作来创建一个新的Fragment，在activity包上右键-->New-->Fragment-->Fragment(Blank)，然后给Fragment命名。

FragmentDrawer.java
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.GestureDetector;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class FragmentDrawer extends Fragment {

    private static String TAG = FragmentDrawer.class.getSimpleName();

    private RecyclerView recyclerView;
    private ActionBarDrawerToggle mDrawerToggle;
    private DrawerLayout mDrawerLayout;
    private NavigationDrawerAdapter adapter;
    private View containerView;
    private static String[] titles = null;
    private FragmentDrawerListener drawerListener;

    public FragmentDrawer() {

    }

    public void setDrawerListener(FragmentDrawerListener listener) {
        this.drawerListener = listener;
    }

    public static List<NavDrawerItem> getData() {
        List<NavDrawerItem> data = new ArrayList<>();

        // preparing navigation drawer items
        for (int i = 0; i < titles.length; i++) {
            NavDrawerItem navItem = new NavDrawerItem();
            navItem.setTitle(titles[i]);
            data.add(navItem);
        }
        return data;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // drawer labels
        titles = getActivity().getResources().getStringArray(R.array.nav_drawer_labels);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflating view layout
        View layout = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
        recyclerView = (RecyclerView) layout.findViewById(R.id.drawerList);

        adapter = new NavigationDrawerAdapter(getActivity(), getData());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), recyclerView, new ClickListener() {
            @Override
            public void onClick(View view, int position) {
                drawerListener.onDrawerItemSelected(view, position);
                mDrawerLayout.closeDrawer(containerView);
            }

            @Override
            public void onLongClick(View view, int position) {

            }
        }));

        return layout;
    }

    public void setUp(int fragmentId, DrawerLayout drawerLayout, final Toolbar toolbar) {
        containerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;
        mDrawerToggle = new ActionBarDrawerToggle(getActivity(), drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) {
            @Override
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
                getActivity().invalidateOptionsMenu();
            }

            @Override
            public void onDrawerClosed(View drawerView) {
                super.onDrawerClosed(drawerView);
                getActivity().invalidateOptionsMenu();
            }

            @Override
            public void onDrawerSlide(View drawerView, float slideOffset) {
                super.onDrawerSlide(drawerView, slideOffset);
                toolbar.setAlpha(1 - slideOffset / 2);
            }
        };

        mDrawerLayout.setDrawerListener(mDrawerToggle);
        mDrawerLayout.post(new Runnable() {
            @Override
            public void run() {
                mDrawerToggle.syncState();
            }
        });

    }

    public static interface ClickListener {
        public void onClick(View view, int position);

        public void onLongClick(View view, int position);
    }

    static class RecyclerTouchListener implements RecyclerView.OnItemTouchListener {

        private GestureDetector gestureDetector;
        private ClickListener clickListener;

        public RecyclerTouchListener(Context context, final RecyclerView recyclerView, final ClickListener clickListener) {
            this.clickListener = clickListener;
            gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
                @Override
                public boolean onSingleTapUp(MotionEvent e) {
                    return true;
                }

                @Override
                public void onLongPress(MotionEvent e) {
                    View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
                    if (child != null && clickListener != null) {
                        clickListener.onLongClick(child, recyclerView.getChildPosition(child));
                    }
                }
            });
        }

        @Override
        public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {

            View child = rv.findChildViewUnder(e.getX(), e.getY());
            if (child != null && clickListener != null && gestureDetector.onTouchEvent(e)) {
                clickListener.onClick(child, rv.getChildPosition(child));
            }
            return false;
        }

        @Override
        public void onTouchEvent(RecyclerView rv, MotionEvent e) {
        }
    }

    public interface FragmentDrawerListener {
        public void onDrawerItemSelected(View view, int position);
    }
}

（22）最后打开主Activity的布局文件（activity_main.xml）并按下面所示来修改布局。在这个布局里面，我们添加了android.support.v4.widget.DrawerLayout来展示导航抽屉菜单。

当然在<fragment>标签里，你需要给出fragmentDrawer正确的路径。

actiivty_main.xml
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <LinearLayout
            android:id="@+id/container_toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <include
                android:id="@+id/toolbar"
                layout="@layout/toolbar" />
        </LinearLayout>

        <FrameLayout
            android:id="@+id/container_body"
            android:layout_width="fill_parent"
            android:layout_height="0dp"
            android:layout_weight="1" />

    </LinearLayout>

    <fragment
        android:id="@+id/fragment_navigation_drawer"
        android:name="androidhive.info.materialdesign.activity.FragmentDrawer"
        android:layout_width="@dimen/nav_drawer_width"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        app:layout="@layout/fragment_navigation_drawer"
        tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>

现在所有的布局文件和java类文件都准备到位了，让我们对MainActivity做一些修改来使导航抽屉工作起来。

（23）打开MainActivity.java文件并做如下修改。

>实现FragmentDrawer.FragmentDrawerListener接口并添加onDrawerItemSelected()重载。

MainActivity.java
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

public class MainActivity extends ActionBarActivity implements FragmentDrawer.FragmentDrawerListener {

    private Toolbar mToolbar;
    private FragmentDrawer drawerFragment;

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

        mToolbar = (Toolbar) findViewById(R.id.toolbar);

        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        drawerFragment = (FragmentDrawer)
                getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
        drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
        drawerFragment.setDrawerListener(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onDrawerItemSelected(View view, int position) {

    }
}

现在如果你运行App，可以看到导航抽屉，在里面有一个头部视图以及一些列表项。

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原文地址：http://www.androidhive.info/2015/04/android-getting-started-with-material-design/