联网加载图片，一个很原始，很古老的办法

加载图片的工具类package com.android1.news.common;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;import java.lang.ref.SoftReference;import java.net.HttpURLConnection;import java.net.URL;import java.util.HashMap;import java.util.Map;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Bitmap.CompressFormat;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.support.v4.util.LruCache;public class LoadImage {//private static Map<String, SoftReference<Bitmap>> softReferences=new HashMap<String, SoftReference<Bitmap>>();private static LruCache<String, Bitmap> cache=new LruCache<String, Bitmap>(1024*1024*3);private Context context;private ImageLoadListener listener;public LoadImage(Context context,ImageLoadListener listener){this.context=context;this.listener=listener;}public interface ImageLoadListener{void imageLoadOk(Bitmap bitmap,String url);}public Bitmap geBitmap(String url){Bitmap bitmap=null;if(url==null || url.length()<=0)return bitmap;//1.先看看内存中有没有  bitmap=getBitmapFromReference(url);if(bitmap!=null){System.out.println("1.内存中的图片");return bitmap;}//2.去看看缓存文件有没有bitmap=getBitmapFromCache(url);if(bitmap!=null){//存入内存//softReferences.put(url, new SoftReference<Bitmap>(bitmap));cache.put(url, bitmap);System.out.println("2.缓存中的图片");return bitmap;}//3.异步加载 getBitmapAsync(url);return bitmap;}private void getBitmapAsync(String url) {ImageAsyncTask imageAsyncTask=new ImageAsyncTask();imageAsyncTask.execute(url);}private Bitmap getBitmapFromCache(String url) {//http://www.baidu.com/gejge/jgejg/gg.jpgString name=url.substring(url.lastIndexOf("/")+1);//File cacheDir=context.getCacheDir();File cacheDir=context.getExternalCacheDir();File[] files=cacheDir.listFiles();if(files==null){return null;}File bitmapFile=null;for (File file : files) {if(file.getName().equals(name)){bitmapFile=file;break;}}if(bitmapFile==null){return null;}Bitmap bitmap=BitmapFactory.decodeFile(bitmapFile.getAbsolutePath());if(bitmap==null)return null;return bitmap;}private Bitmap getBitmapFromReference(String url) {Bitmap bitmap=null;//if(softReferences.containsKey(url)){//bitmap=softReferences.get(url).get();//}bitmap=cache.get(url);return bitmap;}private class ImageAsyncTask extends AsyncTask<String, Void, Bitmap>{private String url;@Overrideprotected Bitmap doInBackground(String... params) {url=params[0];//params[0]--->urlBitmap bitmap=null;try {URL url=new URL(params[0]);HttpURLConnection conn=(HttpURLConnection) url.openConnection();InputStream is=conn.getInputStream();bitmap=BitmapFactory.decodeStream(is);////软引用 //softReferences.put(params[0], new SoftReference<Bitmap>(bitmap));//System.out.println(softReferences.size());cache.put(params[0], bitmap);//缓存文件saveCacheFile(params[0],bitmap);System.out.println("3.网络中的图片");} catch (Exception e) {e.printStackTrace();}return bitmap;}@Overrideprotected void onPostExecute(Bitmap result) {super.onPostExecute(result);if(listener!=null){listener.imageLoadOk(result,url);}}}public void saveCacheFile(String url,Bitmap bitmap) {String name=url.substring(url.lastIndexOf("/")+1);//File cacheDir=context.getCacheDir();File cacheDir=context.getExternalCacheDir();if(!cacheDir.exists()){cacheDir.mkdirs();}OutputStream stream;try {stream = new FileOutputStream(new File(cacheDir, name));bitmap.compress(CompressFormat.JPEG, 100, stream);} catch (FileNotFoundException e) {e.printStackTrace();}}}适配器package com.android1.news.ui.adapter;import com.android1.news.R;import com.android1.news.common.CommonUtil;import com.android1.news.common.LoadImage;import com.android1.news.model.entity.News;import com.android1.news.ui.base.MyBaseAdapter;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.ListView;import android.widget.TextView;public class NewsAdapter extends MyBaseAdapter<news> {private Bitmap defaultBitmap;private LoadImage loadImage;private ListView listView;public NewsAdapter(Context context,ListView listView) {super(context);defaultBitmap=BitmapFactory.decodeResource(context.getResources(), R.drawable.defaultpic);loadImage=new LoadImage(context, listener);this.listView=listView;}@Overridepublic View getMyView(int position, View convertView, ViewGroup parent) {HoldView holdView=null;if(convertView==null){convertView=inflater.inflate(R.layout.item_list_news, null);holdView=new HoldView(convertView);convertView.setTag(holdView);}else{holdView=(HoldView) convertView.getTag();}News news=myList.get(position);holdView.tv_title.setText(news.getTitle());holdView.tv_text.setText(news.getSummary());holdView.tv_from.setText(news.getAuthor());holdView.iv_list_image.setImageBitmap(defaultBitmap);//默认图片String url=news.getList_image();holdView.iv_list_image.setTag(CommonUtil.APPURL+url);System.out.println(CommonUtil.APPURL+url);Bitmap bitmap=loadImage.geBitmap(CommonUtil.APPURL+url);if(bitmap!=null){holdView.iv_list_image.setImageBitmap(bitmap);}return convertView;}public class HoldView {public ImageView iv_list_image;public TextView tv_title;public TextView tv_text;public TextView tv_from;public HoldView(View view) {iv_list_image = (ImageView) view.findViewById(R.id.imageView1);tv_title = (TextView) view.findViewById(R.id.textView1);tv_text = (TextView) view.findViewById(R.id.textView2);tv_from = (TextView) view.findViewById(R.id.textView3);}}private LoadImage.ImageLoadListener listener=new LoadImage.ImageLoadListener(){@Overridepublic void imageLoadOk(Bitmap bitmap, String url) {ImageView iv=(ImageView) listView.findViewWithTag(url);if(iv!=null)   iv.setImageBitmap(bitmap);}};}</news>