Android Volley框架使用(二)

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Android Volley框架使用(一)

使用 Volley 提供的 ImageLoader 工具类，来实现图片的加载、缓存、二次采样。

在使用Volley来从网络获取图片的时候，我们前面介绍了ImageRequest的使用，而其实Volley还提供了一个NetworkImageView类。利用这个类，我们可以更有效率地去从网络去获取图片，因为它里面帮我们多设置了一个缓存，帮我们自己去处理请求的队列。

例:
在activity_main.xml中定义一个GridView

<GridViewandroid:id="@+id/gridview"android:clickable="true"android:numColumns="3"android:layout_width="match_parent"android:layout_height="match_parent"/>

同时定义GridView中的子布局 item.xml:使用NetworkImageView

<com.android.volley.toolbox.NetworkImageViewandroid:id="@+id/networkimage"android:layout_width="300dp"android:layout_height="300dp"/>

MainActivity代码

package com.example.hfs.volleyimageloaderdemo;import android.graphics.Bitmap;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.util.LruCache;import android.widget.GridView;import com.android.volley.RequestQueue;import com.android.volley.toolbox.ImageLoader;import com.android.volley.toolbox.Volley;import com.example.hfs.volleyimageloaderdemo.adapters.MyAdapter;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity {//    imageloader是批量加载图片    private ImageLoader mImageLoader;    private GridView mGridView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initImageLoader();//        使用imageLoader ListView中使用的效果才能体现        initView();        initData();    }    private void initData() {        List<String> list=new ArrayList<>();        String[] imageurls = ImageUrl.imageurls;        for (int i = 0; i < imageurls.length; i++) {            list.add(imageurls[i]);        }        MyAdapter adapter=new MyAdapter(this,list,mImageLoader);        mGridView.setAdapter(adapter);    }    private void initView() {        mGridView = (GridView) findViewById(R.id.gridview);    }    private void initImageLoader() {//        参数1 一个请求队列 实例化一个请求队列        RequestQueue queue= Volley.newRequestQueue(this);        ImageLoader.ImageCache imageCache=new ImageLoader.ImageCache() {//            内存缓存            int maxSize= (int) (Runtime.getRuntime().totalMemory()/8);            LruCache<String,Bitmap> mLruCache=new LruCache<String,Bitmap>(maxSize){//                告诉LruCache存入的数据多大                @Override                protected int sizeOf(String key, Bitmap value) {//                    存入每张图片的大小                    return value.getRowBytes()*value.getHeight();                }            };//            从缓存中获取数据            @Override            public Bitmap getBitmap(String url) {                return mLruCache.get(url);            }//          第一次使用肯定没有数据,联网请求 ,将数据存起来,方便以后使用            @Override            public void putBitmap(String url, Bitmap bitmap) {            mLruCache.put(url,bitmap);            }        };        mImageLoader=new ImageLoader(queue,imageCache);    }}

图片地址类：

package com.example.hfs.volleyimageloaderdemo;/** * Created by HFS on 2016/4/26. */public class ImageUrl {    public static String imageurls[] = new String[] {            "http://img.my.csdn.net/uploads/201407/26/1406383299_1976.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383291_6518.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383291_8239.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383290_9329.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383290_1042.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383275_3977.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383265_8550.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383264_3954.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383264_4787.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383264_8243.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383248_3693.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383243_5120.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383242_3127.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383242_9576.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383242_1721.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383219_5806.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383214_7794.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383213_4418.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383213_3557.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383210_8779.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383172_4577.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383166_3407.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383166_2224.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383166_7301.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383165_7197.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383150_8410.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383131_3736.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383130_5094.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383130_7393.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383129_8813.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383100_3554.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383093_7894.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383092_2432.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383092_3071.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383091_3119.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383059_6589.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383059_8814.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383059_2237.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383058_4330.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406383038_3602.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382942_3079.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382942_8125.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382942_4881.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382941_4559.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382941_3845.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382924_8955.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382923_2141.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382923_8437.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382922_6166.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382922_4843.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382905_5804.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382904_3362.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382904_2312.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382904_4960.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382900_2418.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382881_4490.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382881_5935.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382880_3865.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382880_4662.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382879_2553.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382862_5375.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382862_1748.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382861_7618.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382861_8606.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382861_8949.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382841_9821.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382840_6603.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382840_2405.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382840_6354.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382839_5779.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382810_7578.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382810_2436.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382809_3883.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382809_6269.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382808_4179.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382790_8326.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382789_7174.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382789_5170.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382789_4118.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382788_9532.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382767_3184.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382767_4772.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382766_4924.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382766_5762.jpg",            "http://img.my.csdn.net/uploads/201407/26/1406382765_7341.jpg"};}

自定义的Adapter：

package com.example.hfs.volleyimageloaderdemo.adapters;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import com.android.volley.toolbox.ImageLoader;import com.android.volley.toolbox.NetworkImageView;import com.example.hfs.volleyimageloaderdemo.R;import java.util.List;/** * Created by HFS on 2016/4/26. */public class MyAdapter extends BaseAdapter {    private Context mContext;    private List<String> mList;    private ImageLoader mImageLoader;    public MyAdapter(Context context, List<String> list, ImageLoader imageLoader) {        mContext = context;        mList = list;        mImageLoader = imageLoader;    }    @Override    public int getCount() {        int ret = 0;        if (mList != null) {            ret = mList.size();        }        return ret;    }    @Override    public Object getItem(int position) {        return mList.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        View ret = null;        if (convertView != null) {            ret = convertView;        } else {            ret = LayoutInflater.from(mContext).inflate(R.layout.item, null);        }/*******************************ViewHolde*****************************/        ViewHolder holder = (ViewHolder) ret.getTag();        if (holder == null) {            holder = new ViewHolder();            holder.mImageView = ((ImageView) ret.findViewById(R.id.showImage));            holder.mNetworkImageView= (NetworkImageView) ret.findViewById(R.id.networkimage);            ret.setTag(holder);        }//        //holder.mImageView.setImageResource(R.mipmap.ic_launcher);////        创建一个空的Bitmap//        Bitmap bitmap=Bitmap.createBitmap(300,300, Bitmap.Config.ALPHA_8);//        holder.mImageView.setImageBitmap(bitmap);/*******************************进行赋值**********************************///        final ViewHolder finalHolder = holder;//        mImageLoader.get(mList.get(position), new ImageLoader.ImageListener() {//            @Override//            public void onResponse(ImageLoader.ImageContainer imageContainer, boolean b) {////                Bitmap bitmap = imageContainer.getBitmap();////                if (bitmap != null) {//                    finalHolder.mImageView.setImageBitmap(bitmap);//                }////            }////            @Override//            public void onErrorResponse(VolleyError volleyError) {//                finalHolder.mImageView.setImageResource(R.mipmap.ic_launcher);//            }//        }, 300, 300);        /*******************使用NetworkImageView**************************/        holder.mNetworkImageView.setImageUrl(mList.get(position),mImageLoader);        return ret;    }    private class ViewHolder {        public ImageView mImageView;        public NetworkImageView mNetworkImageView;    }}

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