Android 网络本地显示图片Picasso优化封装使用

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) {
loadCenterC
12114
rop(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);
}
}
}