Picasso封装优化

Picasso在使用过程中，经常忘记一些设置，比如图片的加载方式.centerCrop()，图片的加载优化.fit（），以及对图片的url的处理，因此对图片加载进行统一封装，使用相同的加载方式更有利于后期的维护和扩展。

图片的加载来源

图片的加载来源主要是String，file，Resource，我们都有相应的封装，

为了介绍方便

以下仅仅介绍String方式，以下同时有centerCrop和centerInside，同样我只是介绍centerCrop方式。
示例代码，对应三种加载方式：

public static void loadCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    Picasso.with(context)        .load(checkAndHandleUrl(path))        .placeholder(placeholderResId)        .error(errorResId)        .centerCrop()        .fit()        //.tag(context)        .into(target);  }  public static void loadCenterCrop(@NonNull Context context, @NonNull int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .centerCrop()          .fit()          .into(target);    }  }  public static void loadCenterCrop(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .centerCrop()          .fit()          .into(target);    }  }
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主要的封装场景

1.正常加载图片

public static void loadCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    Picasso.with(context)        .load(checkAndHandleUrl(path))        .placeholder(placeholderResId)        .error(errorResId)        .centerCrop()        .fit()        //.tag(context)        .into(target);  }
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加载带圆角的图片

public static void loaderRoundConnerCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (path == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(checkAndHandleUrl(path))          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerCrop()          .fit()          .into(target);    }  }
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加载圆形图片（常用于圆形头像）

public static void loaderCircleCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (path == null || path.trim().isEmpty()) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(checkAndHandleUrl(path))          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerCrop()          .fit()          .into(target);    }  }
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这些常用的方式都有封装，如果统一调用更方便代码的扩展和维护。

核心代码如下：

public class NewImageLoader {  private NewImageLoader() {    throw new IllegalStateException("no instance");  }  private static <T> void checkNull(T object, String message) {    if (object == null) {      throw new NullPointerException(message);    }  }  /**   * 检查传入的url或者数组中第一个url是不是为空   */  @SuppressWarnings("uncheck") public static boolean isUrlsEmpty(String... urls) {    return urls == null || urls.length == 0 || urls[0] == null || urls[0].trim().isEmpty();  }  @SuppressWarnings("uncheck") public static String checkAndHandleUrl(String... urls) {    if (isUrlsEmpty(urls)) {      return "empty_url";    }    return urls[0];  }  public static Picasso getInstance(Context context) {    return Picasso.with(context);  }  public static void load(@NonNull Context context, String path, @DrawableRes int placeholderResId,      @NonNull ImageView target) {    Picasso.with(context)        .load(checkAndHandleUrl(path))        .placeholder(placeholderResId)        .error(placeholderResId)        .into(target);  }  /**   * 默认图为{@link R.drawable.img_defult}   */  public static void loadCenterCrop(@NonNull Context context, String path,      @NonNull ImageView target) {    loadCenterCrop(context, path, R.drawable.img_defult, target);  }  public static void loadCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @NonNull ImageView target) {    loadCenterCrop(context, path, placeholderResId, placeholderResId, target);  }  public static void loadCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    Picasso.with(context)        .load(checkAndHandleUrl(path))        .placeholder(placeholderResId)        .error(errorResId)        .centerCrop()        .fit()        //.tag(context)        .into(target);  }  public static void loadCenterCrop(@NonNull Context context, @NonNull int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .centerCrop()          .fit()          .into(target);    }  }  public static void loadCenterCrop(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .centerCrop()          .fit()          .into(target);    }  }  /**   * 以下三个方法是centerCrop方式加载带圆角的图片   */  public static void loaderRoundConnerCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (path == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(checkAndHandleUrl(path))          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerCrop()          .fit()          .into(target);    }  }  public static void loaderRoundConnerCenterCrop(@NonNull Context context, int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerCrop()          .fit()          .into(target);    }  }  public static void loaderRoundConnerCenterCrop(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerCrop()          .fit()          .into(target);    }  }  /**   * 以下三个方法是centerCrop方式加载圆形的图片   */  public static void loaderCircleCenterCrop(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (path == null || path.trim().isEmpty()) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(checkAndHandleUrl(path))          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerCrop()          .fit()          .into(target);    }  }  public static void loaderCircleCenterCrop(@NonNull Context context, @NonNull int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerCrop()          .fit()          .into(target);    }  }  public static void loaderCircleCenterCrop(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerCrop()          .fit()          .into(target);    }  }  /****************************** CenterInside ***************************************/  public static void loaderCenterInside(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (path == null || path.trim().isEmpty()) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(checkAndHandleUrl(path))          .placeholder(placeholderResId)          .error(errorResId)          .centerInside()          .fit()          .into(target);    }  }  public static void loaderCenterInside(@NonNull Context context, @NonNull int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .centerInside()          .fit()          .into(target);    }  }  public static void loaderCenterInside(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .centerInside()          .fit()          .into(target);    }  }  /**   * 以下三个方法是centerInside方式加载带圆角的图片   */  public static void loaderRoundConnerCenterInside(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (path == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(checkAndHandleUrl(path))          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerInside()          .fit()          .into(target);    }  }  public static void loaderRoundConnerCenterInside(@NonNull Context context, int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerInside()          .fit()          .into(target);    }  }  public static void loaderRoundConnerCenterInside(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target,      @NonNull int radius, @NonNull int margin) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new RoundedCornersTransformation(DensityUtil.dip2px(context, radius), margin))          .centerInside()          .fit()          .into(target);    }  }  /**   * 以下三个方法是centerInside方式加载圆形的图片   */  public static void loaderCircleCenterInside(@NonNull Context context, String path,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (path == null || path.trim().isEmpty()) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(path)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerInside()          .fit()          .into(target);    }  }  public static void loaderCircleCenterInside(@NonNull Context context, @NonNull int resourceId,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (resourceId == 0) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(resourceId)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerInside()          .fit()          .into(target);    }  }  public static void loaderCircleCenterInside(@NonNull Context context, File file,      @DrawableRes int placeholderResId, @DrawableRes int errorResId, @NonNull ImageView target) {    if (file == null) {      target.setImageDrawable(context.getResources().getDrawable(placeholderResId));    } else {      Picasso.with(context)          .load(file)          .placeholder(placeholderResId)          .error(errorResId)          .transform(new CropCircleTransformation())          .centerInside()          .fit()          .into(target);    }  }}
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