android listview 滚动时异步加载图片的问题
LoadImage.java
Java代码
package com.gowin.cach;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import android.graphics.Bitmap;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
public class LoadImage {
private ExecutorService executorService; // 固定五个线程来
private ImageMemoryCache memoryCache;// 内存缓存
private ImageFileCache fileCache;// 文件缓存
private Map<String, ImageView> taskMap;// 存放任务
public LoadImage() {
executorService = Executors.newFixedThreadPool(10);
memoryCache = new ImageMemoryCache();
fileCache = new ImageFileCache();
taskMap = new HashMap<String, ImageView>();
}
public void addTask(String url, ImageView img) {
Bitmap bitmap=memoryCache.getBitmapFromCache(url);
if(bitmap!=null)
{
img.setImageBitmap(bitmap);
}else
{
synchronized (taskMap) {
taskMap.put(Integer.toString(img.hashCode()), img);
}
}
}
public void doTask() {
synchronized (taskMap) {
Collection<ImageView> con = taskMap.values();
for (ImageView i : con) {
if (i != null) {
if (i.getTag() != null) {
loadImage((String) i.getTag(), i);
}
}
}
taskMap.clear();
}
}
private void loadImage(String url, ImageView img) {
/*** 加入新的任务***/
executorService.submit(new TaskWithResult(new TaskHandler(url, img),
url));
}
/*** 获得一个图片,从三个地方获取,首先是内存缓存,然后是文件缓存,最后从网络获取***/
private Bitmap getBitmap(String url) {
// 从内存缓存中获取图片
Bitmap result;
result = memoryCache.getBitmapFromCache(url);
if (result == null) {
// 文件缓存中获取
result = fileCache.getImage(url);
if (result == null) {
// 从网络获取
result = ImageGetForHttp.downloadBitmap(url);
if (result != null) {
memoryCache.addBitmapToCache(url, result);
fileCache.saveBmpToSd(result, url);
}
} else {
// 添加到内存缓存
memoryCache.addBitmapToCache(url, result);
}
}
return result;
}
/*** 完成消息***/
private class TaskHandler extends Handler {
String url;
ImageView img;
public TaskHandler(String url, ImageView img) {
this.url = url;
this.img = img;
}
@Override
&nbs
补充：移动开发 , Android ,
