android - 线圈图像缓存不适用于 Jetpack Compose

Question

我正在使用 coil(version 2.1.0)从 URL 加载图像。当有网络连接时，图像加载正常。但是，当没有网络连接时，图像不会像我预期的那样从缓存中提取出来。这是我的一段代码。

class App : Application(), ImageLoaderFactory {

    override fun newImageLoader(): ImageLoader {
       return ImageLoader.Builder(this)
            .memoryCache {
                MemoryCache.Builder(this)
                    .maxSizePercent(0.25)
                    .build()
            }
            .diskCache {
                DiskCache.Builder()
                    .directory(cacheDir.resolve("image_cache"))
                    .maxSizeBytes(5 * 1024 * 1024)
                    .build()
            }
            .build()
    }
  }

在撰写中:

                val context = LocalContext.current
                val placeholderImage = R.drawable.ic_placeholder
    
                val imageRequest = ImageRequest.Builder(context)
                    .data(imageUrl)
                    .memoryCacheKey(imageUrl)
                    .diskCacheKey(imageUrl)
                    .placeholder(placeholderImage)
                    .error(placeholderImage)
                    .fallback(placeholderImage)
                    .diskCachePolicy(CachePolicy.ENABLED)
                    .memoryCachePolicy(CachePolicy.ENABLED)
                    .transformations(CircleCropTransformation())
                    .build()

                AsyncImage(
                    model = imageRequest,
                    modifier = Modifier.size(64.dp),
                    contentDescription = null,
                    imageLoader = context.imageLoader
                )

当设备处于离线状态时，它只会加载占位符图像，而不是像预期的那样从缓存中加载图像。我在这里缺少什么？

Answer 1

coil 将根据 http header 中的 Cache-Control 字段来决定是否需要磁盘缓存。

这里是coil 2.0.0的更新日志

• New: Introduce a public DiskCache API.
  • Use ImageLoader.Builder.diskCache and DiskCache.Builder to configure the disk cache.
  • You should not use OkHttp's Cache with Coil 2.0. See here for moreinfo.
  • Cache-Control and other cache headers are still supported - except Vary headers, as the cache only checks that the URLs match.Additionally, only responses with a response code in the range[200..300) are cached.
  • Existing disk caches will be cleared when upgrading to 2.0.

如果需要强制缓存，参见https://coil-kt.github.io/coil/recipes/#headers .而且我认为最好使用 addHeader 来避免丢弃其他 http header 字段。