CacheInterceptor class

Interceptor that provides response caching with configurable strategies.

Supports multiple caching strategies:

• CacheStrategy.cacheFirst: serve cache immediately — stale included — and revalidate in the background
• CacheStrategy.networkFirst: try network first, fall back to cache (possibly stale) on failure
• CacheStrategy.httpCacheAware: follow the server's Cache-Control / ETag directives
• CacheStrategy.cacheOnly: only use cache, and only while it is valid
• CacheStrategy.networkOnly: always use network, never read cache

The TTL is enforced here, not by the CacheStorage: a backend only stores and returns. See CacheStorage.get.

Whenever a cached body is handed back, Response.extra carries fromCacheKey, plus fromCacheStaleKey when that body had expired — read them through response.isFromCache / response.isStale.

Example:

final cacheInterceptor = CacheInterceptor(
  config: CacheConfig(
    strategy: CacheStrategy.networkFirst,
    defaultTtl: Duration(minutes: 5),
  ),
);
dio.interceptors.add(cacheInterceptor);