UtilCache (jdonframework 6.9 API)

java.lang.Object
- com.jdon.cache.UtilCache

```
public class UtilCache
extends Object
```
Generalized caching utility. Provides a number of caching features:
- Limited or unlimited element capacity
- If limited, removes elements with the LRU (Least Recently Used) algorithm
- Keeps track of when each element was loaded into the cache
- Using the expireTime can report whether a given element has expired
- Counts misses and hits

字段概要

字段
限定符和类型	字段和说明
`Map`	`cacheLineTable` A hashtable containing a CacheLine object with a value and a loadTime for each element. for above jdk1.5
`protected long`	`expireTime` Specifies the amount of time since initial loading before an element will be reported as expired.
`protected long`	`hitCount` A count of the number of cache hits
`ConcurrentLinkedList`	`keyLRUList` A list of the elements order by Least Recent Use
`protected long`	`maxSize` The maximum number of elements in the cache.
`protected long`	`missCount` A count of the number of cache misses
`static String`	`module`
`protected boolean`	`useSoftReference` Specifies whether or not to use soft references for this cache, defaults to false

构造器概要

构造器
构造器和说明
`UtilCache(int maxSize, long expireTime, boolean useSoftReference)`
`UtilCache(PropsUtil propsUtil)` Default constructor, all members stay at default values as defined in cache.properties, or the defaults in this file if cache.properties is not found, or there are no 'default' entries in it.

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`void`	`clear()` Removes all elements from this cache
`void`	`clearAllCaches()` Removes all elements from this cache
`void`	`clearCounters()` Clears the hit and miss counters
`void`	`clearExpired()` Clears all expired cache entries; also clear any cache entries where the SoftReference in the CacheLine object has been cleared by the gc
`boolean`	`containsKey(Object key)` Returns a boolean specifying whether or not an element with the specified key is in the cache.
`Object`	`get(Object key)` Gets an element from the cache according to the specified key.
`long`	`getExpireTime()` return the current expire time for the cache elements
`long`	`getHitCount()` Returns the number of successful hits on the cache
`long`	`getMaxSize()` Returns the current maximum number of elements in the cache
`long`	`getMissCount()` Returns the number of cache misses
`boolean`	`getUseSoftReference()` Return whether or not the cache lines should use a soft reference to the data
`protected boolean`	`hasExpired(CacheLine line)`
`boolean`	`hasExpired(Object key)` Returns a boolean specifying whether or not the element corresponding to the key has expired.
`Set`	`keySet()`
`void`	`put(Object key, Object value)` Puts or loads the passed element into the cache
`void`	`remove(Object key)` Removes an element from the cache according to the specified key
`void`	`setExpireTime(long expireTime)` Sets the expire time for the cache elements.
`void`	`setMaxSize(long maxSize)` Sets the maximum number of elements in the cache.
`protected void`	`setPropertiesParams(PropsUtil propsUtil, String cacheName)`
`long`	`size()` Returns the number of elements currently in the cache
`void`	`startMon(long expireTime)`
`void`	`stop()`
`Collection`	`values()`

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - module
```
public static String module
```
  - keyLRUList
```
public final ConcurrentLinkedList keyLRUList
```
    A list of the elements order by Least Recent Use
  - cacheLineTable
```
public final Map cacheLineTable
```
    A hashtable containing a CacheLine object with a value and a loadTime for each element. for above jdk1.5
  - hitCount
```
protected volatile long hitCount
```
    A count of the number of cache hits
  - missCount
```
protected volatile long missCount
```
    A count of the number of cache misses
  - maxSize
```
protected volatile long maxSize
```
    The maximum number of elements in the cache. If set to 0, there will be no limit on the number of elements in the cache.
  - expireTime
```
protected volatile long expireTime
```
    Specifies the amount of time since initial loading before an element will be reported as expired. If set to 0, elements will never expire.
  - useSoftReference
```
protected volatile boolean useSoftReference
```
    Specifies whether or not to use soft references for this cache, defaults to false
- 构造器详细资料
  - UtilCache
```
public UtilCache(PropsUtil propsUtil)
```
    Default constructor, all members stay at default values as defined in cache.properties, or the defaults in this file if cache.properties is not found, or there are no 'default' entries in it.
  - UtilCache
```
public UtilCache(int maxSize,
                 long expireTime,
                 boolean useSoftReference)
```
- 方法详细资料
  - startMon
```
public void startMon(long expireTime)
```
  - setPropertiesParams
```
protected void setPropertiesParams(PropsUtil propsUtil,
                                   String cacheName)
```
  - put
```
public void put(Object key,
                Object value)
```
    Puts or loads the passed element into the cache
    
    参数:
    
    key - The key for the element, used to reference it in the hastables and LRU linked list
    
    value - The value of the element
  - get
```
public Object get(Object key)
```
    Gets an element from the cache according to the specified key. If the requested element hasExpired, it is removed before it is looked up which causes the function to return null.
    
    参数:
    
    key - The key for the element, used to reference it in the hastables and LRU linked list
    
    返回:
    
    The value of the element specified by the key
  - remove
```
public void remove(Object key)
```
    Removes an element from the cache according to the specified key
    
    参数:
    
    key - The key for the element, used to reference it in the hastables and LRU linked list
  - keySet
```
public Set keySet()
```
  - values
```
public Collection values()
```
  - clear
```
public void clear()
```
    Removes all elements from this cache
  - clearAllCaches
```
public void clearAllCaches()
```
    Removes all elements from this cache
  - getHitCount
```
public long getHitCount()
```
    Returns the number of successful hits on the cache
    
    返回:
    
    The number of successful cache hits
  - getMissCount
```
public long getMissCount()
```
    Returns the number of cache misses
    
    返回:
    
    The number of cache misses
  - clearCounters
```
public void clearCounters()
```
    Clears the hit and miss counters
  - setMaxSize
```
public void setMaxSize(long maxSize)
```
    Sets the maximum number of elements in the cache. If 0, there is no maximum.
    
    参数:
    
    maxSize - The maximum number of elements in the cache
  - getMaxSize
```
public long getMaxSize()
```
    Returns the current maximum number of elements in the cache
    
    返回:
    
    The maximum number of elements in the cache
  - setExpireTime
```
public void setExpireTime(long expireTime)
```
    Sets the expire time for the cache elements. If 0, elements never expire.
    
    参数:
    
    expireTime - The expire time for the cache elements
  - getExpireTime
```
public long getExpireTime()
```
    return the current expire time for the cache elements
    
    返回:
    
    The expire time for the cache elements
  - getUseSoftReference
```
public boolean getUseSoftReference()
```
    Return whether or not the cache lines should use a soft reference to the data
  - size
```
public long size()
```
    Returns the number of elements currently in the cache
    
    返回:
    
    The number of elements currently in the cache
  - containsKey
```
public boolean containsKey(Object key)
```
    Returns a boolean specifying whether or not an element with the specified key is in the cache. If the requested element hasExpired, it is removed before it is looked up which causes the function to return false.
    
    参数:
    
    key - The key for the element, used to reference it in the hastables and LRU linked list
    
    返回:
    
    True is the cache contains an element corresponding to the specified key, otherwise false
  - hasExpired
```
public boolean hasExpired(Object key)
```
    Returns a boolean specifying whether or not the element corresponding to the key has expired. Only returns true if element is in cache and has expired. Error conditions return false, if no expireTable entry, returns true. Always returns false if expireTime <= 0. Also, if SoftReference in the CacheLine object has been cleared by the gc return true.
    
    参数:
    
    key - The key for the element, used to reference it in the hastables and LRU linked list
    
    返回:
    
    True is the element corresponding to the specified key has expired, otherwise false
  - hasExpired
```
protected boolean hasExpired(CacheLine line)
```
  - clearExpired
```
public void clearExpired()
```
    Clears all expired cache entries; also clear any cache entries where the SoftReference in the CacheLine object has been cleared by the gc
  - stop
```
public void stop()
```

类 UtilCache

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

module

keyLRUList

cacheLineTable

hitCount

missCount

maxSize

expireTime

useSoftReference

构造器详细资料

UtilCache

UtilCache

方法详细资料

startMon

setPropertiesParams

put

get

remove

keySet

values

clear

clearAllCaches

getHitCount

getMissCount

clearCounters

setMaxSize

getMaxSize

setExpireTime

getExpireTime

getUseSoftReference

size

containsKey

hasExpired

hasExpired

clearExpired

stop