Android利用Volley异步载入数据完整具体演示样例(二)

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);

	}

}

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>