## org.apache.http.impl.client.cache.ehcache
Class EhcacheHttpCacheStorage

    java.lang.Object
      org.apache.http.impl.client.cache.ehcache.EhcacheHttpCacheStorage

All Implemented Interfaces:
  HttpCacheStorage

    public class EhcacheHttpCacheStorage

extends Object
implements HttpCacheStorage

This class is a storage backend for cache entries that uses the popular Ehcache cache implementation. In particular, this backend allows for spillover to disk, where the cache can be effectively larger than memory, and cached responses are paged into and out of memory from disk as needed.

N.B. Since the Ehcache is configured ahead of time with a maximum number of cache entries, this effectively ignores the `maximum cache entries` specified by a provided `CacheConfig`.

Please refer to the Ehcache documentation for details on how to configure the Ehcache itself.

Since:
  4.1

Constructor Summary
`EhcacheHttpCacheStorage(net.sf.ehcache.Ehcache cache)` Constructs a storage backend using the provided Ehcache with default configuration options.
`EhcacheHttpCacheStorage(net.sf.ehcache.Ehcache cache, CacheConfig config)` Constructs a storage backend using the provided Ehcache with the given configuration options.
`EhcacheHttpCacheStorage(net.sf.ehcache.Ehcache cache, CacheConfig config, HttpCacheEntrySerializer serializer)` Constructs a storage backend using the provided Ehcache with the given configuration options, but using an alternative cache entry serialization strategy.

Method Summary
`HttpCacheEntry` `getEntry(String key)` Retrieves the cache entry stored under the given key or null if no entry exists under that key.
`void` `putEntry(String key, HttpCacheEntry entry)` Store a given cache entry under the given key.
`void` `removeEntry(String key)` Deletes/invalidates/removes any cache entries currently stored under the given key.
`void` `updateEntry(String key, HttpCacheUpdateCallback callback)` Atomically applies the given callback to update an existing cache entry under a given key.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### EhcacheHttpCacheStorage

    public EhcacheHttpCacheStorage(net.sf.ehcache.Ehcache cache)

  Constructs a storage backend using the provided Ehcache with default configuration options.

  Parameters:
    `cache` - where to store cached origin responses

### EhcacheHttpCacheStorage

    public EhcacheHttpCacheStorage(net.sf.ehcache.Ehcache cache,
                                   CacheConfig config)

  Constructs a storage backend using the provided Ehcache with the given configuration options.

  Parameters:
    `cache` - where to store cached origin responses
    `config` - cache storage configuration options - note that the setting for max object size will be ignored and should be configured in the Ehcache instead.

### EhcacheHttpCacheStorage

    public EhcacheHttpCacheStorage(net.sf.ehcache.Ehcache cache,
                                   CacheConfig config,
                                   HttpCacheEntrySerializer serializer)

  Constructs a storage backend using the provided Ehcache with the given configuration options, but using an alternative cache entry serialization strategy.

  Parameters:
    `cache` - where to store cached origin responses
    `config` - cache storage configuration options - note that the setting for max object size will be ignored and should be configured in the Ehcache instead.
    `serializer` - alternative serialization mechanism

Method Detail

### putEntry

    public void putEntry(String key,
                         HttpCacheEntry entry)
                  throws IOException

  Description copied from interface: `HttpCacheStorage`
  Store a given cache entry under the given key.

  Specified by:
    `putEntry` in interface `HttpCacheStorage`
  Parameters:
    `key` - where in the cache to store the entry
    `entry` - cached response to store
  Throws:
    `IOException`

### getEntry

    public HttpCacheEntry getEntry(String key)
                            throws IOException

  Description copied from interface: `HttpCacheStorage`
  Retrieves the cache entry stored under the given key or null if no entry exists under that key.

  Specified by:
    `getEntry` in interface `HttpCacheStorage`
  Parameters:
    `key` - cache key
  Returns:
    an `HttpCacheEntry` or `null` if no entry exists
  Throws:
    `IOException`

### removeEntry

    public void removeEntry(String key)

  Description copied from interface: `HttpCacheStorage`
  Deletes/invalidates/removes any cache entries currently stored under the given key.

  Specified by:
    `removeEntry` in interface `HttpCacheStorage`

### updateEntry

    public void updateEntry(String key,
                            HttpCacheUpdateCallback callback)
                     throws IOException,
                            HttpCacheUpdateException

  Description copied from interface: `HttpCacheStorage`
  Atomically applies the given callback to update an existing cache entry under a given key.

  Specified by:
    `updateEntry` in interface `HttpCacheStorage`
  Parameters:
    `key` - indicates which entry to modify
    `callback` - performs the update; see `HttpCacheUpdateCallback` for details, but roughly the callback expects to be handed the current entry and will return the new value for the entry.
  Throws:
    `IOException`
    `HttpCacheUpdateException`

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