注：Volley库的NetworkImageView怎么用，网上有很多资料，这里只是记述我在项目中使用NetworkImageView读取网络图片然后通过ListView显示出来的做法和步骤（由于是截取删减项目代码，可能会有遗漏的地方），以备我以后查用（能帮助其他人将是我的荣幸），因为我也是在同学的帮助以及查询网络下完成的。

<ListView
      android:id="@+id/lv_typelist"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:divider="@null"
      android:scrollbars="none"/>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <LinearLayout
        android:layout_width="80dp"
        android:layout_height="100dp">
        <com.android.volley.toolbox.NetworkImageView
            android:id="@+id/imageview_typeImg"
            android:layout_width="match_parent"
            android:layout_height="80dp"
            android:scaleType="centerCrop"
            android:layout_gravity="center"
            android:gravity="center">
        </com.android.volley.toolbox.NetworkImageView>

        <TextView
            android:id="@+id/textview_typeName"
            android:layout_width="match_parent"
            android:layout_height="20dp"
            android:layout_gravity="center"
            android:gravity="center"/>
    </LinearLayout>
</LinearLayout>

2、创建自定义的Application，用来获取Volley的队列对象

public class MyApplication extends Application {
    public static RequestQueue queue;
    @Override
    public void onCreate() {
        super.onCreate();
        queue = Volley.newRequestQueue(getApplicationContext());
    }
    public static RequestQueue getHttpQueue() {
        return queue;
    }
}

修改AndroidManifest.xml文件

android:name=".MyApplication

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.user.myfirstapp">
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:name=".MyApplication"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppBaseTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

import android.graphics.Bitmap;
import android.support.v4.util.LruCache;
import com.android.volley.toolbox.ImageLoader;

public class BitmapCache implements ImageLoader.ImageCache {
    //内存缓存
    private static LruCache<String, Bitmap> mMemoryCache;
    //单例
    private static BitmapCache lruImageCache;
    private BitmapCache(){
        // Get the Max available memory
        int maxMemory = (int) Runtime.getRuntime().maxMemory();
        int cacheSize = maxMemory/10;
        mMemoryCache = new LruCache<String, Bitmap>(cacheSize){
            @Override
            protected int sizeOf(String key, Bitmap bitmap){
                return bitmap.getRowBytes() * bitmap.getHeight();
            }
        };
    }
    //获取单例实例
    public static BitmapCache instance(){
        if(lruImageCache == null){
            lruImageCache = new BitmapCache();
        }
        return lruImageCache;
    }
    //从内存获取图片
    @Override
    public Bitmap getBitmap(String url){
        return mMemoryCache.get(url);
    }
    //图片放入到内存
    @Override
    public void putBitmap(String url, Bitmap bitmap){
        if(getBitmap(url) == null){
            mMemoryCache.put(url, bitmap);
        }
    }
}

4、Activity或Fragment中代码(我这里是在Fragment中)

    private View view;
    private ListView lv_type;
    private TextView typename;
    private ImageView right_top_img;
    private Gson gson;
    private List<GoodsType> list;
    private ArrayList<HashMap<String, Object>> listItem;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        view =inflater.inflate(R.layout.flg_type,container,false);

        lv_type=(ListView)view.findViewById(R.id.lv_typelist);
        ....此处省略一些代码....

        showImageList();

        ....此处省略一些代码....

        return view;
    }

    private void showImageList(){
        if(list!=null&&list.size()>0) {
            NetworkImageViewAdapter adapter = new NetworkImageViewAdapter(getActivity());
            lv_type.setAdapter(adapter);
            //点击事件
            lv_type.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                if(id==-1)
                    return;
                int realPosition=(int)id;
                ListView lv = (ListView)ListView;
                Object object=lv.getItemAtPosition(realPosition);
                //转对应的自定义的实体类型
                GoodsType gt = (GoodsType)object;
                //分类id
                int typeId = gt.getId();
                .........
            }
        }
    }

    public class NetworkImageViewAdapter extends BaseAdapter {
        private LayoutInflater layoutInflater = null;
        class ViewHolder {
            TextView name;
            NetworkImageView image;
        }
        public NetworkImageViewAdapter(Context context)
        {
            layoutInflater = LayoutInflater.from(context);
        }
        @Override
        public int getCount() {
            return list == null ? 0 : list.size();
        }

        @Override
        public Object getItem(int position) {
            return list == null ? null : list.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder viewHolder = null;
            if (convertView == null) {
                viewHolder = new ViewHolder();
                convertView = layoutInflater.inflate(R.layout.twoleveltypelist_item, null);
                viewHolder.name = (TextView) convertView.findViewById(R.id.textview_typeName);
                viewHolder.image = (NetworkImageView) convertView.findViewById(R.id.imageview_typeImg);
                convertView.setTag(viewHolder);
            } else {
                viewHolder = (ViewHolder) convertView.getTag();
            }
            GoodsType gt = list.get(position);
            viewHolder.name.setText(gt.getTypeName());
	    ImageLoader imageLoader = new ImageLoader(MyApplication.getHttpQueue(), BitmapCache.instance());
	    viewHolder.image.setTag("url");
            viewHolder.image.setImageUrl(gt.getTypeImg(), imageLoader);
            return convertView;
        }
    }