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.getBytes("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：

wemall doraemonAndroid app商城详情地址：

wemall官网地址：

wemall 开源微商城 ，微信商城，商城源码，三级分销，微生鲜，微水果，微外卖，微订餐---专业的o2o系统