com.hannesdorfmann.httpkit.cache

Interface Cache<K,V>

Type Parameters:

K - The type of the key. Usually its String

V - The type of the value. Usually Object, if you want to create a all in one cache.

All Known Implementing Classes:

HybridCache

public interface Cache<K,V>

A cache is a kind of Key Value Map. But its just a public api. The real caches can be plugged in to fit your requirements. There are basically two types of caches that can be plugged in:

• MemoryCache: Can be accessed directly and should have O(1) implementation. The requested object is already in memory and does not need to be parsed
• DiskCache: Is a cache that must be read from disk. The real object must be parsed and therefore it can take some time to query this type of cache

Author:

Hannes Dorfmann

Method Summary

Methods

Modifier and Type	Method and Description
void	addDiskCache(DiskCache<K,V> cache) Add a disk cache
void	addMemoryCache(MemoryCache<K,V> cache) Adds a memory cache
void	clear() Cleans the cache, by removing all cache entries
CacheEntry<V>	getFromDiskCache(K key, Class<?> targetClass, int collectionType) Get a value from the cache by passing additional information for the ParserWriter
CacheEntry<V>	getFromMemoryCache(K key) Do a quick look up.
ParserWriterPool	getParserWriterPool() Get the ParserWriterPool.
void	onLowMemory() This method is called, when the memory of the device runs low (RAM).
void	putRawToDiskCache(K key, byte[] value, String mimeType, String charsetEncoding, Long expirationTimeStamp, String eTag) Write as raw bytes
void	putToDiskCache(K key, V value, String mimeType, String charsetEncoding, Long expirationTimeStamp, String eTag) Write
void	putToMemoryCache(K key, CacheEntry<V> value) Put a already existing CacheEntry to the memory cache.
void	putToMemoryCache(K key, V value, String mimeType, String charsetEncoding, Long expirationTimeStamp, String eTag) Adds and create a new CacheEntry to the cache.
void	remove(K key) Removes the Entry
void	removeDiskCache(DiskCache<K,V> cache) remove a Disk cache
void	removeMemoryCache(MemoryCache<K,V> cache) remove a memory cache
void	updateExpirationTimestamp(K key, long expirationTimestamp) Updates the cached entries expiration timestamp (identified by the key)

Method Detail

getFromDiskCache

CacheEntry<V> getFromDiskCache(K key,
                             Class<?> targetClass,
                             int collectionType)
                               throws Exception

Get a value from the cache by passing additional information for the ParserWriter

Parameters:

key - The key

targetClass - The target class, to where the retrieved entry should be mapped (with an objectmapper)

collectionType - The returning collection type, like List, etc. This must be one of the constatns specified int ParserWriter.COLLECTION_TYPE_NONE, ParserWriter.COLLECTION_TYPE_LIST, etc. ...

Returns:

Throws:

Exception

getFromMemoryCache

CacheEntry<V> getFromMemoryCache(K key)

Do a quick look up. Quick means, that no long running action like loading a resource file or something from the disk cache is done with this method call. So this one is used for memory cache lookups.

Parameters:

key - The key

Returns:

The value you try to find, or null if not found quickly and a longer resource loading must be done

addMemoryCache

void addMemoryCache(MemoryCache<K,V> cache)

Adds a memory cache

Parameters:

cache -

removeMemoryCache

void removeMemoryCache(MemoryCache<K,V> cache)

remove a memory cache

Parameters:

cache -

addDiskCache

void addDiskCache(DiskCache<K,V> cache)

Add a disk cache

Parameters:

cache -

removeDiskCache

void removeDiskCache(DiskCache<K,V> cache)

remove a Disk cache

Parameters:

cache -

putToMemoryCache

void putToMemoryCache(K key,
                    V value,
                    String mimeType,
                    String charsetEncoding,
                    Long expirationTimeStamp,
                    String eTag)

Adds and create a new CacheEntry to the cache.

Parameters:

key - The key

value - The Value for the given key

mimeType - The mime type of the value. This is important to find the correct parser for the stored cache value

charsetEncoding - The charset like, UTF-8 etc. that is used, to encode the string content (is useless for binary data)

expirationTimeStamp - The expiration value

eTag - The ETag

putToMemoryCache

void putToMemoryCache(K key,
                    CacheEntry<V> value)

Put a already existing CacheEntry to the memory cache. This will normally be called if you want to put a entry retrieved from disc cache to the meme

Parameters:

key -

value -

putToDiskCache

void putToDiskCache(K key,
                  V value,
                  String mimeType,
                  String charsetEncoding,
                  Long expirationTimeStamp,
                  String eTag)
                    throws Exception

Write

Parameters:

key -

value -

mimeType -

charsetEncoding -

expirationTimeStamp -

eTag -

Throws:

Exception

putRawToDiskCache

void putRawToDiskCache(K key,
                     byte[] value,
                     String mimeType,
                     String charsetEncoding,
                     Long expirationTimeStamp,
                     String eTag)
                       throws Exception

Write as raw bytes

Parameters:

key -

value -

mimeType -

charsetEncoding -

expirationTimeStamp -

eTag -

Throws:

Exception

remove

void remove(K key)
            throws IOException

Removes the Entry

Parameters:

key -

Throws:

IOException

getParserWriterPool

ParserWriterPool getParserWriterPool()

Get the ParserWriterPool. Add in there any ParserWriter your cache should be able to handle and parse

onLowMemory

void onLowMemory()

This method is called, when the memory of the device runs low (RAM).

clear

void clear()
           throws IOException

Cleans the cache, by removing all cache entries

Throws:

IOException

updateExpirationTimestamp

void updateExpirationTimestamp(K key,
                             long expirationTimestamp)
                               throws IOException

Updates the cached entries expiration timestamp (identified by the key)

Parameters:

key -

expirationTimestamp -

Throws:

IOException