Android利用Volley异步载入数据完整具体演示样例 _Android

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MainActivity例如以下:

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描写叙述: * 去年一个项目中简单的使用了Volley,參见: * http://blog.csdn.net/lfdfhl/article/details/12223345 * 近期guolin写了几篇文章具体介绍Volley,所以在此比較系统地学习一下. * 在本演示样例中,主要包含: * 1 利用ImageRequest为ImageView载入网络图片 * 2 利用ImageLoader为ImageView载入网络图片 * 3 利用NetworkImageView为ImageView载入网络图片 * * 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源代码分析,请參见: *http://blog.csdn.net/guolin_blog/article/details/17656437 * 4 自己定义的XMLRequest和GsonRequest,请參见: *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载入网络图片 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() { @Override public void onErrorResponse(VolleyError error) { System.out.println(" 获取图片失败,所以载入一个默认图片" ); mImageView.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_launcher)); } }); mRequestQueue.add(mImageRequest); } //利用ImageLoader为ImageView载入网络图片 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 //请參见: //http://blog.csdn.net/lfdfhl/article/details/18350601 private class ImageCacheImpl implements ImageCache { private LruCache< String, Bitmap> mLruCache; public ImageCacheImpl() { int maxSize = 15 * 1024 * 1024; mLruCache = new LruCache< String, Bitmap> (maxSize) { @Override protected int sizeOf(String key, Bitmap bitmap) { return bitmap.getRowBytes() * bitmap.getHeight(); } }; }@Override public Bitmap getBitmap(String url) { return mLruCache.get(url); } @Override public void putBitmap(String url, Bitmap bitmap) { mLruCache.put(url, bitmap); } } //利用NetworkImageView为ImageView载入网络图片 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); } }

【Android利用Volley异步载入数据完整具体演示样例】main.xml例如以下:

< ?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>