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
| version | 1.1, 03/09/22 |
| since | 1.5 |
| Methods |
|---|
| abstract public CacheResponse |
get(URI uri, String rqstMethod, Map rqstHeaders) throws IOException
Retrieve the cached response based on the requesting uri,
request method and request headers. Typically this method is
called by the protocol handler before it sends out the request
to get the network resource. If a cached response is returned,
that resource is used instead.
|
| abstract public 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 a WriteableByteChannel 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 |
| return | a CacheRequest for recording the
response to be cached. Null return indicates that
the caller does not intend to cache the response. |
| Throws | IOException: if an I/O error occurs |
| Throws | IllegalArgumentException: if any one of the arguments is
null |
|
