Android利用Volley异步加载数据完整详细示例(二)

MainActivity如下:

package cc.y;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.os.Bundle;import android.util.LruCache;import android.widget.ImageView;import com.android.volley.RequestQueue;import com.android.volley.Response;import com.android.volley.VolleyError;import com.android.volley.toolbox.ImageLoader;import com.android.volley.toolbox.ImageLoader.ImageCache;import com.android.volley.toolbox.ImageLoader.ImageListener;import com.android.volley.toolbox.ImageRequest;import com.android.volley.toolbox.NetworkImageView;import com.android.volley.toolbox.Volley;/** * Demo描述: * 去年一个项目中简单的使用了Volley,参见: * http://blog.csdn.net/lfdfhl/article/details/12223345 * 最近guolin写了几篇文章详细介绍Volley,所以在此比较系统地学习一下. * 在本示例中,主要包括: * 1 利用ImageRequest为ImageView加载网络图片 * 2 利用ImageLoader为ImageView加载网络图片 * 3 利用NetworkImageView为ImageView加载网络图片 *  * 注意事项: * 1 引入jar包volley.jar * 2 网络权限<uses-permission android:name="android.permission.INTERNET"/> * 3 Volley源码分析,请参见: *   http://blog.csdn.net/guolin_blog/article/details/17656437 * 4 自定义的XMLRequest和GsonRequest,请参见: *   http://blog.csdn.net/guolin_blog/article/details/17612763 *  * 学习资料: * http://blog.csdn.net/guolin_blog/article/details/17482165 * Thank you very much * */public class MainActivity extends Activity {private Context mContext;private RequestQueue mRequestQueue;private String mUrl="http://avatar.csdn.net/6/6/D/1_lfdfhl.jpg";private ImageView mImageView;private ImageRequest mImageRequest;private ImageLoader mImageLoader;private ImageListener mImageListener;private NetworkImageView mNetworkImageView;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        init();        //volley_ImageRequest();        //volley_ImageLoader();        volley_NetworkImageView();    }        private void init(){    mContext=this;    mImageView=(ImageView) findViewById(R.id.imageView);    mNetworkImageView=(NetworkImageView) findViewById(R.id.networkImageView);    }        //利用ImageRequest为ImageView加载网络图片private void volley_ImageRequest() {mRequestQueue = Volley.newRequestQueue(mContext);mImageRequest = new ImageRequest(mUrl, new Response.Listener<Bitmap>() {  @Override  public void onResponse(Bitmap response) {mImageView.setImageBitmap(response);}},    0,    0,    Config.ARGB_8888,    new Response.ErrorListener() {@Overridepublic void onErrorResponse(VolleyError error) {System.out.println("获取图片失败,所以加载一个默认图片");mImageView.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_launcher));}});mRequestQueue.add(mImageRequest);}//利用ImageLoader为ImageView加载网络图片private void volley_ImageLoader(){mRequestQueue = Volley.newRequestQueue(mContext);mImageLoader=new ImageLoader(mRequestQueue, new ImageCacheImpl());mImageListener=ImageLoader.getImageListener(mImageView, R.drawable.ic_launcher, R.drawable.ic_launcher);mImageLoader.get(mUrl, mImageListener);//mImageLoader.get(mUrl, mImageListener,250,250);}//利用LruCache实现图片缓存机制//请参见://http://blog.csdn.net/lfdfhl/article/details/18350601private class ImageCacheImpl implements ImageCache {private LruCache<String, Bitmap> mLruCache;public ImageCacheImpl() {int maxSize = 15 * 1024 * 1024;mLruCache = new LruCache<String, Bitmap>(maxSize) {@Overrideprotected int sizeOf(String key, Bitmap bitmap) {return bitmap.getRowBytes() * bitmap.getHeight();}};}@Overridepublic Bitmap getBitmap(String url) {return mLruCache.get(url);}@Overridepublic void putBitmap(String url, Bitmap bitmap) {mLruCache.put(url, bitmap);}}//利用NetworkImageView为ImageView加载网络图片private void volley_NetworkImageView(){mRequestQueue = Volley.newRequestQueue(mContext);mImageLoader=new ImageLoader(mRequestQueue, new ImageCacheImpl());mNetworkImageView.setDefaultImageResId(R.drawable.ic_launcher);mNetworkImageView.setErrorImageResId(R.drawable.ic_launcher);mNetworkImageView.setImageUrl(mUrl, mImageLoader);}}

main.xml如下:

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="学习Volley(二)"         android:layout_centerHorizontal="true"     />        <ImageView         android:id="@+id/imageView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:layout_marginTop="50dip"        />        <com.android.volley.toolbox.NetworkImageView        android:id="@+id/networkImageView"        android:layout_width="120dip"        android:layout_height="120dip"        android:layout_centerHorizontal="true"        android:layout_marginTop="150dip"    /></RelativeLayout>