Module java.base

Class ResponseCache

  • public abstract class ResponseCache
    extends Object
    Represents implementations of URLConnection caches. An instance of such a class can be registered with the system by doing ResponseCache.setDefault(ResponseCache), and the system will call this object in order to:
    • store resource data which has been retrieved from an external source into the cache
    • try to fetch a requested resource that may have been stored in the cache
    The ResponseCache implementation decides which resources should be cached, and for how long they should be cached. If a request resource cannot be retrieved from the cache, then the protocol handlers will fetch the resource from its original location. The settings for URLConnection#useCaches controls whether the protocol is allowed to use a cached response. For more information on HTTP caching, see RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1
    • Constructor Detail

      • ResponseCache

        public ResponseCache()
    • Method Detail

      • setDefault

        public static void setDefault​(ResponseCache responseCache)
        Sets (or unsets) the system-wide cache. Note: non-standard procotol handlers may ignore this setting.
        responseCache - The response cache, or null to unset the cache.
        SecurityException - If a security manager has been installed and it denies NetPermission("setResponseCache")
        See Also:
      • put

        public abstract CacheRequest put​(URI uri,
                                         URLConnection conn)
                                  throws IOException
        The protocol handler calls this method after a resource has been retrieved, and the ResponseCache must decide whether or not to store the resource in its cache. If the resource is to be cached, then put() must return a CacheRequest object which contains an OutputStream that the protocol handler will use to write the resource into the cache. If the resource is not to be cached, then put must return null.
        uri - a URI used to reference the requested network resource
        conn - - a URLConnection instance that is used to fetch the response to be cached
        a CacheRequest for recording the response to be cached. Null return indicates that the caller does not intend to cache the response.
        IOException - if an I/O error occurs
        IllegalArgumentException - if any one of the arguments is null