Retrieve the cached response based on the requesting uri, request method and request headers.

  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.
Returns: a CacheResponse instance if available from cache, or null otherwise
Parameters:
- uri - a URI used to reference the requested network resource
- rqstMethod - a String representing the request method
- rqstHeaders - - a Map from request header field names to lists of field values representing the current request headers
Throws:
- IOException - if an I/O error occurs
- IllegalArgumentException - if any one of the arguments is null
See Also: URLConnection.setUseCaches(boolean), URLConnection.getUseCaches(), URLConnection.setDefaultUseCaches(boolean), URLConnection.getDefaultUseCaches(),

  Gets the system-wide response cache.

  Gets the system-wide response cache.
Returns: the system-wide ResponseCache
Throws:
- SecurityException - If a security manager has been installed and it denies {@link NetPermission}("getResponseCache")
Since: 1.5
See Also: ResponseCache.setDefault(ResponseCache),

  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.

  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.
Returns: a CacheRequest for recording the response to be cached. Null return indicates that the caller does not intend to cache the response.
Parameters:
- uri - a URI used to reference the requested network resource
- conn - - a URLConnection instance that is used to fetch the response to be cached
Throws:
- IOException - if an I/O error occurs
- IllegalArgumentException - if any one of the arguments is null

  Sets (or unsets) the system-wide cache.

  Sets (or unsets) the system-wide cache.

Note: non-standard procotol handlers may ignore this setting.
Parameters:
- responseCache - The response cache, or null to unset the cache.
Throws:
- SecurityException - If a security manager has been installed and it denies {@link NetPermission}("setResponseCache")
Since: 1.5
See Also: ResponseCache.getDefault(),