android 实现类似微信缓存和即时更新好友头像示例

 /**
 * @param context 上下文
 */
public BitmapUtils(Context context) {
  this(context, null);
}

/**
 * @param context 上下文
 * @param diskCachePath 磁盘高速缓存路径
 */
public BitmapUtils(Context context, String diskCachePath) {
  if (context == null) {
    throw new IllegalArgumentException("context may not be null");
  }

  this.context = context.getApplicationContext();
  globalConfig = BitmapGlobalConfig.getInstance(this.context, diskCachePath);
  defaultDisplayConfig = new BitmapDisplayConfig();
}

/**
 * 
 * @param context 上下文
 * @param diskCachePath 磁盘高速缓存路径
 * @param memoryCacheSize 内存缓存空间大小
 */
public BitmapUtils(Context context, String diskCachePath, int memoryCacheSize) {
  this(context, diskCachePath);
  globalConfig.setMemoryCacheSize(memoryCacheSize);
}

/**
 * 
 * @param context 上下文
 * @param diskCachePath 磁盘高速缓存路径
 * @param memoryCacheSize 内存缓存空间大小
 * @param diskCacheSize 磁盘高速缓存空间大小
 */
public BitmapUtils(Context context, String diskCachePath, int memoryCacheSize, int diskCacheSize) {
  this(context, diskCachePath);
  globalConfig.setMemoryCacheSize(memoryCacheSize);
  globalConfig.setDiskCacheSize(diskCacheSize);
}

/**
 * 
 * @param context 上下文
 * @param diskCachePath 磁盘高速缓存路径
 * @param memoryCachePercent 内存缓存百分比
 */
public BitmapUtils(Context context, String diskCachePath, float memoryCachePercent) {
  this(context, diskCachePath);
  globalConfig.setMemCacheSizePercent(memoryCachePercent);
}
   /**
 * 
 * @param context 上下文
 * @param diskCachePath 磁盘高速缓存路径
 * @param memoryCachePercent 内存缓存百分比
 * @param diskCacheSize 磁盘缓存空间大小
 */
public BitmapUtils(Context context, String diskCachePath, float memoryCachePercent, int diskCacheSize) {
  this(context, diskCachePath);
  globalConfig.setMemCacheSizePercent(memoryCachePercent);
  globalConfig.setDiskCacheSize(diskCacheSize);
}

BitmapUtils bitmap = new BitmapUtils(context);

 /**
 * 根据图片路径，显示到具体的View上
 * @param container 要把图片显示到的View
 * @param uri 图片路径
 */
public <T extends View> void display(T container, String uri) {
  display(container, uri, null, null);
}

/**
 * 根据图片路径，显示到具体的View上
 * @param container 要把图片显示到的View
 * @param uri 图片路径
 * @param displayConfig
 */
public <T extends View> void display(T container, String uri, BitmapDisplayConfig displayConfig) {
  display(container, uri, displayConfig, null);
}

/**
 * 根据图片路径，显示到具体的View上
 * @param container 要把图片显示到的View
 * @param uri 图片路径
 * @param callBack 加载过程回调各种状态
 */
public <T extends View> void display(T container, String uri, BitmapLoadCallBack<T> callBack) {
  display(container, uri, null, callBack);
}  
 
 /**
 * 根据图片路径，显示到具体的View上
 * @param container 要把图片显示到的View
 * @param uri 图片路径
 * @param displayConfig 位图显示配置
 * @param callBack
 */
public <T extends View> void display(T container, String uri, BitmapDisplayConfig displayConfig, BitmapLoadCallBack<T> callBack) {
  if (container == null) {
    return;
  }

  if (callBack == null) {
    callBack = new DefaultBitmapLoadCallBack<T>();
  }

  if (displayConfig == null || displayConfig == defaultDisplayConfig) {
    displayConfig = defaultDisplayConfig.cloneNew();
  }
  // Optimize Max 
  BitmapSize size = displayConfig.getBitmapMaxSize();SizedisplayConfig.setBitmapMaxSize(BitmapCommonUtils.optimizeMaxSizeByView(container, size.getWidth(), size.getHeight()));

  container.clearAnimation();

  if (TextUtils.isEmpty(uri)) {
    callBack.onLoadFailed(container, uri, displayConfig.getLoadFailedDrawable());
    return;
  }

  // start loading
  callBack.onPreLoad(container, uri, displayConfig);

  // find bitmap from mem cache.
  Bitmap bitmap = globalConfig.getBitmapCache().getBitmapFromMemCache(uri, displayConfig);

  if (bitmap != null) {
    callBack.onLoadStarted(container, uri, displayConfig);
    callBack.onLoadCompleted(
        container,
        uri,
        bitmap,
        displayConfig,
        BitmapLoadFrom.MEMORY_CACHE);
  } else if (!bitmapLoadTaskExist(container, uri, callBack)) {

    final BitmapLoadTask<T> loadTask = new BitmapLoadTask<T>(container, uri, displayConfig, callBack);

    // get executor
    PriorityExecutor executor = globalConfig.getBitmapLoadExecutor();
    File diskCacheFile = this.getBitmapFileFromDiskCache(uri);
    boolean diskCacheExist = diskCacheFile != null && diskCacheFile.exists();
    if (diskCacheExist && executor.isBusy()) {
      executor = globalConfig.getDiskCacheExecutor();
    }
    // set loading image
    Drawable loadingDrawable = displayConfig.getLoadingDrawable();
    callBack.setDrawable(container, new AsyncDrawable<T>(loadingDrawable, loadTask));

    loadTask.setPriority(displayConfig.getPriority());
    loadTask.executeOnExecutor(executor);
  }
}