package com.example.asyncloadpicture;

 import java.util.ArrayList;

 import android.app.Activity;

 import android.content.Context;

 import android.graphics.Bitmap;

 import android.graphics.BitmapFactory;

 import android.os.AsyncTask;

 import android.os.Bundle;

 import android.widget.GridView;

 /**

  * @author ymw

  * @data 2014-12-03

  */

 public class MainActivity extends Activity {

     private GridView gridViewImg;

     private ArrayList<ImageEntity> imageList = new ArrayList<ImageEntity>();

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_main);

         gridViewImg = (GridView) findViewById(R.id.gridViewImg);

         initData();

     }

     private void initData() {

         for (int i = 0; i < 15; i++) {

             ImageEntity b = new ImageEntity();

             b.setImage(BitmapFactory.decodeResource(getResources(),

                     R.drawable.nopicture));

             imageList.add(b);

         }

         ImageAdapter adapter = new ImageAdapter(getApplicationContext(),

                 imageList);

         gridViewImg.setAdapter(adapter);

         String[] params = {

                 "https://images0.cnblogs.com/i/169207/201408/112229149526951.png",

                 "p2" };

         new ImageLoadTask(getApplicationContext(), adapter).execute(params);

     }

     /** 图片异步加载类 */

     public class ImageLoadTask extends AsyncTask<String, Void, Void> {

         private ImageAdapter adapter;

         public ImageLoadTask(Context context, ImageAdapter adapter) {

             this.adapter = adapter;

         }

         @Override

         protected Void doInBackground(String... params) {

             String url = params[0];// 获取传来的参数，图片uri地址

             String p2 = params[1];

             for (int i = 0; i < adapter.getCount(); i++) {

                 ImageEntity bean = (ImageEntity) adapter.getItem(i);

                 Bitmap bitmap = BitmapFactory.decodeStream(Request

                         .HandlerData(url));

                 bean.setImage(bitmap);

                 publishProgress(); // 通知去更新UI

             }

             return null;

         }

         public void onProgressUpdate(Void... voids) {

             if (isCancelled())

                 return;

             // 更新UI

             adapter.notifyDataSetChanged();

         }

     }

     /** 图片实体 */

     public class ImageEntity {

         private Bitmap image;

         public Bitmap getImage() {

             return image;

         }

         public void setImage(Bitmap image) {

             this.image = image;

         }

     }

 }

 package com.example.asyncloadpicture;

 import java.util.ArrayList;

 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.example.asyncloadpicture.MainActivity.ImageEntity;

 /**

  *

  * @author ymw

  * @data 2014-12-03 图片适配器

  */

 public class ImageAdapter extends BaseAdapter {

     private Context _context;

     private ArrayList<ImageEntity> _list;

     public ImageAdapter(Context context, ArrayList<ImageEntity> imageList) {

         this._context = context;

         this._list = imageList;

     }

     @Override

     public int getCount() {

         return _list.size();

     }

     @Override

     public Object getItem(int position) {

         return _list.get(position);

     }

     @Override

     public long getItemId(int position) {

         return position;

     }

     @Override

     public View getView(int position, View convertView, ViewGroup parent) {

         LayoutInflater inflater = LayoutInflater.from(_context);

         convertView = inflater.inflate(R.layout.gridview_item, null);

         ImageView imgView = (ImageView) convertView.findViewById(R.id.imgView);

         ImageEntity b = _list.get(position);

         // 如果有图片则读取，没有则跳过

         if (b.getImage() != null) {

             imgView.setImageBitmap(b.getImage());

         }

         return convertView;

     }

 }

 package com.example.asyncloadpicture;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import java.net.URLConnection;

 import android.graphics.drawable.Drawable;

 import android.util.Log;

 /**

  * 工具类，主要根据url读取图片返回流的方法

  *

  * @author ymw

  *

  */

 public class Request {

     public static InputStream HandlerData(String url) {

         InputStream inStream = null;

         try {

             URL feedUrl = new URL(url);

             URLConnection conn = feedUrl.openConnection();

             conn.setConnectTimeout(10 * 1000);

             inStream = conn.getInputStream();

         } catch (Exception e) {

             e.printStackTrace();

         }

         return inStream;

     }

     /** 直接返回Drawable对象设置图片 */

     public static Drawable loadImageFromNetwork(String imageUrl) {

         Drawable drawable = null;

         try {

             // 可以在这里通过文件名来判断，是否本地有此图片

             drawable = Drawable.createFromStream(

                     new URL(imageUrl).openStream(), "image.jpg");

         } catch (IOException e) {

             Log.d("test", e.getMessage());

         }

         if (drawable == null) {

             Log.d("test", "null drawable");

         } else {

             Log.d("test", "not null drawable");

         }

         return drawable;

     }

 }