/**
  * 注意: 次構造器不支持下載進度提示功能
  * @param context
  * @param withCache 是否支持緩存
  *     false--不帶緩存
  *     true--支持緩存功能，默認緩存路徑在外置存儲緩沖目錄中的picasso-big-cache文件夾中
  */
 public ImageLoader(Context context, boolean withCache) {
  this(context, null, withCache);
 }

 /**
  * 支持下載進度提示，以及設置緩存路徑
  * @param context
  * @param listener 下載進度監(jiān)聽器
  * @param cachePath 緩存路徑字符串
  */
 public ImageLoader(Context context, ProgressListener listener, String cachePath) {
  // TODO extend to support multiple libraries as Glide
  // TODO must be initialized and kept as an member instance to avoid losing cache
  Picasso.Builder builder = setupLoaderClientWithCachePath(context, listener, cachePath);
  setupListener(builder);

  picasso = builder.build();
  picasso.setIndicatorsEnabled(BuildConfig.DEBUG);
  picasso.setLoggingEnabled(BuildConfig.DEBUG);
 }

 /**
  * 支持下載進度提示，以及設置緩存路徑為默認路徑picasso-big-cache
  * @param context
  * @param listener 下載進度監(jiān)聽器
  * @param withCache 是否支持緩存
  */
 public ImageLoader(Context context, ProgressListener listener, boolean withCache) {
  // TODO extend to support multiple libraries as Glide
  // TODO must be initialized and kept as an member instance to avoid losing cache
  Picasso.Builder builder = setupLoaderClient(context, listener, withCache);
  setupListener(builder);

  picasso = builder.build();
  picasso.setIndicatorsEnabled(BuildConfig.DEBUG);
  picasso.setLoggingEnabled(BuildConfig.DEBUG);
 }

public void shutdown() {
  if (picasso == null) return;

  Logger.d(Logger.TAG, "Image loader has been shutdown");
  picasso.shutdown();
  callback = null;
 }

public ImageLoader cancelRequest(ImageView imageView) {
  picasso.cancelRequest(imageView);
  return this;
 }

public ImageLoader load(final int resourceId) {
  cleanResources();
  this.imageResourceId = resourceId;
  return this;
 }

public ImageLoader load(final String imageUri) {
  cleanResources();
  this.imageUri = imageUri;
  return this;
 }

public ImageLoader withPlaceholder(final int placeholder) {
  this.placeholder = placeholder;
  return this;
 }

public ImageLoader withErrorImage(final int errorImage) {
  this.errorImage = errorImage;
  return this;
 }

public ImageLoader withTag(final String tag) {
  this.tag = tag;
  return this;
 }

public void pause(final String tag) {
  if (picasso == null) return;

  picasso.pauseTag(tag);
 }

public void resume(final String tag) {
  if (picasso == null) return;

  picasso.resumeTag(tag);
 }

public ImageLoader withCallback(final Callback callback) {
  this.callback = callback;
  return this;
 }

public ImageLoader fit() {
  this.fit = true;
  return this;
 }

 public ImageLoader centerCrop() {
  this.centerCrop = true;
  return this;
 }

 public ImageLoader centerInside() {
  this.centerInside = true;
  return this;
 }

 public ImageLoader resize(final int widthResId, final int heightResId) {
  this.widthResId = widthResId;
  this.heigthResId = heightResId;
  return this;
 }

public void into(final ImageView imageView) {
  run(imageView);
 }