预加载一堆图像，当所有图像都完成时 return

Question

这里是一个相对的代码示例。基本上我想做的是预加载一些图像（因此是 for 循环）。预加载有效，但我不知道它何时完成。我知道有听众，但我不确定它们是如何工作的

当for循环中的所有图片完全加载时，是否有解决方法仅return来自该方法。这有意义吗？

public void method(){
    final Activity activity = getCurrentActivity();
            activity.runOnUiThread(new Runnable() {

                @Override
                public void run() {
                    for (int i = 0; i < sources.size(); i++) {


                        final ReadableMap source = sources.getMap(i);
                        final GlideUrl glideUrl = FastImageViewConverter.glideUrl(source);
                        final Priority priority = FastImageViewConverter.priority(source);
                        Glide
                                .with(activity.getApplicationContext())
                                .load(glideUrl)
                                .priority(priority)
                                .placeholder(TRANSPARENT_DRAWABLE)
                                .diskCacheStrategy(DiskCacheStrategy.SOURCE)
                                .preload()
                                .listener(new RequestListener<Uri, GlideDrawable>() {
                                    @Override public boolean onException(Exception e, Uri model, Target<GlideDrawable> target, boolean isFirstResource) {
                                        return false;
                                    }
                                    @Override public boolean onResourceReady(GlideDrawable resource, Uri model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
                                        // easy
                                        return false;
                                        // impossible?
                                    }
                                });
                    }
                }
            });

}

Answer 1

因为您知道要预加载多少张图片，也许您可以设置一个计数器，然后在 onResourceReady 中您可以递增该计数器。一旦达到您要预加载的图像数量，您就完成了，您可以继续执行其他操作

Answer 2

这不是最佳答案，但可能适合您的情况:)

public void method(){
    final Activity activity = getCurrentActivity();
            activity.runOnUiThread(new Runnable() {

                @Override
                public void run() {
                    int counter = sources.size();
                    for (int i = 0; i < sources.size(); i++) {


                        final ReadableMap source = sources.getMap(i);
                        final GlideUrl glideUrl = FastImageViewConverter.glideUrl(source);
                        final Priority priority = FastImageViewConverter.priority(source);
                        Glide
                                .with(activity.getApplicationContext())
                                .load(glideUrl)
                                .priority(priority)
                                .placeholder(TRANSPARENT_DRAWABLE)
                                .diskCacheStrategy(DiskCacheStrategy.SOURCE)
                                .preload()
                                .listener(new RequestListener<Uri, GlideDrawable>() {
                                    @Override public boolean onException(Exception e, Uri model, Target<GlideDrawable> target, boolean isFirstResource) {
                                        counter--;
                                        if counter == 0 {
                                            return your result here
                                        }
                                        return false;
                                    }
                                    @Override public boolean onResourceReady(GlideDrawable resource, Uri model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
                                        counter--;
                                        if counter == 0 {
                                            return your result here
                                        }
                                        return false;
                                        // impossible?
                                    }
                                });
                    }
                }
            });

}

预加载一堆图像，当所有图像都完成时 return

Preload a bunch of images, and return when all of them are complete

java

android

android-glide