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public abstract class

ResponseCache

extends Object
java.lang.Object
   ↳ java.net.ResponseCache

Class Overview

ResponseCache implements URLConnection caches. System default cache can be registered by invoking ResponseCache.setDefault(ResponseCache), and can be retrieved by invoking ResponseCache.getDefault. If URLConnection#useCaches is set, URLConnection class will use ResponseCache to store and get resources. Whether the resource is cached depends on ResponseCache implementation. If a request resource is cached, protocol handler will fecth it from the cache. If the protocol handler fails to get resource from the cache, it turns to get the resource from its original location.

Summary

Public Constructors
ResponseCache()
Constructor method.
Public Methods
abstract CacheResponse get(URI uri, String rqstMethod, Map<String, List<String>> rqstHeaders)
Gets the cached response according to requesting uri,method and headers.
static ResponseCache getDefault()
Gets system default response cache.
abstract CacheRequest put(URI uri, URLConnection conn)
Protocol handler calls this method after retrieving resources.
static void setDefault(ResponseCache responseCache)
Sets the system default response cache when responseCache is not null.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public ResponseCache ()

Constructor method.

Public Methods

public abstract CacheResponse get (URI uri, String rqstMethod, Map<String, List<String>> rqstHeaders)

Gets the cached response according to requesting uri,method and headers.

Parameters
uri A URL represents requesting uri.
rqstMethod A String represents requesting method.
rqstHeaders A Map from request header field names to lists of field values represents requesting headers.
Returns
  • A CacheResponse object if the request is available in the cache. Otherwise, this method returns null.
Throws
IOException If an I/O error is encountered.
IllegalArgumentException If any one of the parameters is null

public static ResponseCache getDefault ()

Gets system default response cache.

Returns
  • default ResponseCache.
Throws
SecurityException If a security manager is installed and it doesn't have NetPermission("getResponseCache").

public abstract CacheRequest put (URI uri, URLConnection conn)

Protocol handler calls this method after retrieving resources. The ResponseCache decides whether the resource should be cached. If the resource needs to be cached, this method will return a CacheRequest with a WriteableByteChannel, and then, protocol handler will use this channel to write the resource data into the cache. Otherwise, if the resource doesn't need to be cached, it returns null.

Returns
  • a CacheRequest which contains WriteableByteChannel if the resource is cached. Otherwise, it returns null.
Throws
IOException If an I/O error is encountered.
IllegalArgumentException If any one of the parameters is null.

public static void setDefault (ResponseCache responseCache)

Sets the system default response cache when responseCache is not null. Otherwise, the method unsets the system default response cache. This setting may be ignored by some non-standard protocols.

Parameters
responseCache Set default ResponseCache. If responseCache is null, it unsets the cache.
Throws
SecurityException If a security manager is installed and it doesn't have NetPermission("setResponseCache").