wemall app商城源码中基于JAVA的Android异步加载图片管理器代码

wemall doraemon是Android客户端程序，服务端采用wemall微信商城，不对原商城做任何修改，只需要在原商城目录下上传接口文件即可完成服务端的配置，客户端可随意定制修改。本文分享其中关于异步加载图片管理器，供技术员参考学习。

package com.inuoer.util;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.lang.ref.SoftReference;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Map;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

/**
*
* @author Administrator
* @desc 异步加载图片管理器
*
*/
public class LoaderImpl {
//内存中的软应用缓存
private Map<String, SoftReference<Bitmap>> imageCache;

//是否缓存图片至本地文件
private boolean cache2FileFlag = false;

//缓存目录,默认是/data/data/package/cache/目录
private String cachedDir;

public LoaderImpl(Map<String, SoftReference<Bitmap>> imageCache){
this.imageCache = imageCache;
}

/**
* 是否缓存图片至外部文件
* @param flag
*/
public void setCache2File(boolean flag){
cache2FileFlag = flag;
}

/**
* 设置缓存图片到外部文件的路径
* @param cacheDir
*/
public void setCachedDir(String cacheDir){
this.cachedDir = cacheDir;
}

/**
* 从网络端下载图片
* @param url 网络图片的URL地址
* @param cache2Memory 是否缓存(缓存在内存中)
* @return bitmap 图片bitmap结构
*
*/
public Bitmap getBitmapFromUrl(String url, boolean cache2Memory){
Bitmap bitmap = null;
try{
URL u = new URL(url);
HttpURLConnection conn = (HttpURLConnection)u.openConnection();
InputStream is = conn.getInputStream();
bitmap = BitmapFactory.decodeStream(is);

if(cache2Memory){
//1.缓存bitmap至内存软引用中
imageCache.put(url, new SoftReference<Bitmap>(bitmap));
if(cache2FileFlag){
//2.缓存bitmap至/data/data/packageName/cache/文件夹中
String fileName = getMD5Str(url);
String filePath = this.cachedDir + "/" +fileName;
FileOutputStream fos = new FileOutputStream(filePath);
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
}
}

is.close();
conn.disconnect();
return bitmap;
}catch(IOException e){
e.printStackTrace();
return null;
}
}

/**
* 从内存缓存中获取bitmap
* @param url
* @return bitmap or null.
*/
public Bitmap getBitmapFromMemory(String url){
Bitmap bitmap = null;
if(imageCache.containsKey(url)){
synchronized(imageCache){
SoftReference<Bitmap> bitmapRef = imageCache.get(url);
if(bitmapRef != null){
bitmap = bitmapRef.get();
return bitmap;
}
}
}
//从外部缓存文件读取
if(cache2FileFlag){
bitmap = getBitmapFromFile(url);
if(bitmap != null)
imageCache.put(url, new SoftReference<Bitmap>(bitmap));
}

return bitmap;
}

/**
* 从外部文件缓存中获取bitmap
* @param url
* @return
*/
private Bitmap getBitmapFromFile(String url){
Bitmap bitmap = null;
String fileName = getMD5Str(url);
if(fileName == null)
return null;

String filePath = cachedDir + "/" + fileName;

try {
FileInputStream fis = new FileInputStream(filePath);
bitmap = BitmapFactory.decodeStream(fis);
} catch (FileNotFoundException e) {
e.printStackTrace();
bitmap = null;
}
return bitmap;
}

/**
* MD5 加密
*/
private static String getMD5Str(String str) {
MessageDigest messageDigest = null;
try {
messageDigest = MessageDigest.getInstance("MD5");
messageDigest.reset();
messageDigest.update(str.getByt
4000
es("UTF-8"));
} catch (NoSuchAlgorithmException e) {
//          System.out.println("NoSuchAlgorithmException caught!");
return null;
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
return null;
}

byte[] byteArray = messageDigest.digest();
StringBuffer md5StrBuff = new StringBuffer();
for (int i = 0; i < byteArray.length; i++) {
if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));
else
md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
}

return md5StrBuff.toString();
}

/**
* MD5 加密
private static String getMD5Str(Object...objects){
StringBuilder stringBuilder=new StringBuilder();
for (Object object : objects) {
stringBuilder.append(object.toString());
}
return getMD5Str(stringBuilder.toString());
}*/
}

原文详情地址：http://git.oschina.net/zzunet/wemall-doraemon/commit/e8f303df5663dc69fe47bb9623222149d40e3956

wemall doraemonAndroid app商城详情地址：http://www.koahub.com/home/product/55

wemall官网地址：http://www.wemallshop.com

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