如何使用 Kotlin Multiplatform(Android, iOS) Ktor Client 实现自定义缓存机制

Question

我正在从事Kotlin多平台项目。我使用Ktor客户端进行网络调用。我想根据一些不基于响应头的自定义逻辑缓存一些请求。

HttpCache提供的功能Ktor是响应头驱动的，我无法覆盖它，因为类的数量是Internal.

如何启用Ktor自定义缓存？

Answer 1

我认为您应该创建一个自定义 HttpClient 功能来拦截请求和响应并处理缓存

1 创建Cache接口并实现：

interface Cache {
    suspend fun get(request: HttpRequest): HttpResponse?
    suspend fun store(request: HttpRequest, response: HttpResponse) }

class InMemoryCache : Cache {
    private val cache = mutableMapOf<String, HttpResponse>()

    override suspend fun get(request: HttpRequest): HttpResponse? {
        return cache[request.url.toString()]
    }

    override suspend fun store(request: HttpRequest, response: HttpResponse) {
        cache[request.url.toString()] = response
    }
}

2 创建自定义 HttpClient：

class CustomCache(private val cache: Cache) {
    class Config {
        lateinit var cache: Cache
    }

    companion object Feature : HttpClientFeature<Config, CustomCache> {
        override val key: AttributeKey<CustomCache> = AttributeKey("CustomCache")

        override fun prepare(block: Config.() -> Unit): CustomCache {
            val config = Config().apply(block)
            return CustomCache(config.cache)
        }

        override fun install(feature: CustomCache, scope: HttpClient) {
            scope.sendPipeline.intercept(HttpSendPipeline.Before) {
                val cachedResponse = cache.get(context.request)
                if (cachedResponse != null) {
                    context.response = cachedResponse
                    finish()
                }
            }

            scope.receivePipeline.intercept(HttpReceivePipeline.After) { response ->
                cache.store(context.request, response)
            }
        }
    }
}

3 在 HttpClient 中使用它：

val httpClient = HttpClient {
    install(CustomCache) {
        cache = InMemoryCache()
    }
}

毕竟 CustomCache 功能将拦截请求和响应，使用提供的 Cache 实现来存储和检索缓存的响应

如果对你有帮助我会很高兴