Class NullSafeCache<K,V>

java.lang.Object

cloud.opencode.base.cache.NullSafeCache<K,V>

Type Parameters:

K - the type of keys | 键类型

V - the type of values | 值类型

Security | 安全性:

• Thread-safe: Yes (delegates to thread-safe cache) - 线程安全: 是（委托给线程安全的缓存）
• Null-safe: Yes (primary purpose) - 空值安全: 是（主要功能）

All Implemented Interfaces:

Cache<K,V>

public class NullSafeCache<K,V>
extends Object
implements Cache<K,V>

Null-Safe Cache - Cache that can store and distinguish null values 空值安全缓存 - 可以存储和区分 null 值的缓存

Wraps null values in a sentinel object to distinguish between "key not present" and "key present with null value".

将 null 值包装在哨兵对象中，以区分"键不存在"和"键存在但值为 null"。

Features | 主要功能:

• Store null values - 存储 null 值
• Distinguish miss from null - 区分未命中和 null
• Optional-based API - 基于 Optional 的 API
• Transparent wrapping/unwrapping - 透明包装/解包

Usage Examples | 使用示例:

// Create null-safe cache
NullSafeCache<String, User> cache = NullSafeCache.wrap(baseCache);

// Store null value
cache.put("user:deleted", null);  // Stores null as sentinel

// Distinguish between miss and null
Optional<User> result = cache.getIfPresent("user:deleted");
if (result == null) {
    // Key not in cache
} else if (result.isEmpty()) {
    // Key present with null value
} else {
    // Key present with actual value
    User user = result.get();
}

// Or use containsKey first
if (cache.containsKey("user:deleted")) {
    User user = cache.get("user:deleted");  // May return null
}

Since:

JDK 25, opencode-base-cache V2.0.4

Author:

Leon Soo www.LeonSoo.com

See Also:

• OpenCode.cloud

Method Summary

Modifier and Type	Method	Description
ConcurrentMap<K,V>	asMap()	Get a concurrent map view of this cache 获取 ConcurrentMap 视图
AsyncCache<K,V>	async()	Get async view of this cache 获取异步视图
void	cleanUp()	Perform cleanup (expired entries, etc.)
boolean	containsKey(K key)	Check if key exists 检查键是否存在
boolean	containsNullValue(K key)	Check if the key is present with a null value 检查键是否存在且值为 null
Set<Map.Entry<K,V>>	entries()	Get snapshot of all entries 获取所有条目的快照
long	estimatedSize()	Get estimated entry count (fast) 获取估算条目数（快速）
V	get(K key)	Get value by key, returns null if not present 根据键获取值，不存在返回 null
V	get(K key, Function<? super K, ? extends V> loader)	Get value by key, load using loader if not present 根据键获取值，不存在时通过 loader 加载
Map<K,V>	getAll(Iterable<? extends K> keys)	Get all values for given keys, returns only existing entries 批量获取，仅返回存在的条目
Map<K,V>	getAll(Iterable<? extends K> keys, Function<? super Set<? extends K>, ? extends Map<K,V>> loader)	Get all values, load missing keys using loader 批量获取，缺失的键通过 loader 加载
Optional<V>	getIfPresent(K key)	Get value as Optional, distinguishing null from absent 以 Optional 形式获取值，区分 null 和不存在
void	invalidate(K key)	Invalidate a single key 使单个键失效
void	invalidateAll()	Invalidate all entries 清空所有缓存
void	invalidateAll(Iterable<? extends K> keys)	Invalidate multiple keys 批量失效
Set<K>	keys()	Get snapshot of all keys 获取所有键的快照
CacheMetrics	metrics()	Get detailed cache metrics with latency percentiles 获取带延迟百分位数的详细缓存指标
String	name()	Get cache name 获取缓存名称
void	put(K key, V value)	Put a key-value pair into cache 放入键值对
void	putAll(Map<? extends K, ? extends V> map)	Put all key-value pairs into cache 批量放入
void	putAllWithTtl(Map<? extends K, ? extends V> map, Duration ttl)	Put all entries with custom TTL 批量放入并指定自定义 TTL
boolean	putIfAbsent(K key, V value)	Put if the key is absent, returns true if successful 不存在时放入，成功返回 true
boolean	putIfAbsentWithTtl(K key, V value, Duration ttl)	Put if absent with custom TTL 不存在时放入并指定自定义 TTL
void	putWithTtl(K key, V value, Duration ttl)	Put a key-value pair with custom TTL (overrides default expiration) 放入键值对并指定自定义 TTL（覆盖默认过期时间）
long	size()	Get exact entry count (may be slow) 获取精确条目数（可能较慢）
CacheStats	stats()	Get cache statistics 获取缓存统计信息
Collection<V>	values()	Get snapshot of all values 获取所有值的快照
static <K,V> NullSafeCache<K,V>	wrap(Cache<K,V> cache)	Wrap an existing cache with null-safe behavior 用空值安全行为包装现有缓存

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface Cache

clear, compute, computeIfAbsent, computeIfPresent, containsValue, entryIterator, entryParallelStream, entryStream, forEach, forEachKey, forEachValue, getAndRemove, getByPattern, getOptional, getOrDefault, getOrNull, invalidateByPattern, invalidateByValue, invalidateIf, isEmpty, keyIterator, keyParallelStream, keyStream, merge, putAllIfAbsent, putIfPresent, removeIfEquals, removeIfPresent, replace, replace, replaceAll, resetStats, updateAll, updateTtl, updateTtl, updateTtlAll, valueParallelStream, valueStream

Method Details

wrap

public static <K,V> NullSafeCache<K,V> wrap(Cache<K,V> cache)

Wrap an existing cache with null-safe behavior 用空值安全行为包装现有缓存

Type Parameters:

K - key type | 键类型

V - value type | 值类型

Parameters:

cache - the cache to wrap | 要包装的缓存

Returns:

null-safe cache | 空值安全缓存

get

public V get(K key)

Description copied from interface: Cache

Get value by key, returns null if not present 根据键获取值，不存在返回 null

Specified by:

get in interface Cache<K,V>

Parameters:

key - the key | 键

Returns:

the value or null | 值或 null

get

public V get(K key,
 Function<? super K, ? extends V> loader)

Description copied from interface: Cache

Get value by key, load using loader if not present 根据键获取值，不存在时通过 loader 加载

Specified by:

get in interface Cache<K,V>

Parameters:

key - the key | 键

loader - the loader function | 加载函数

Returns:

the value | 值

getIfPresent

public Optional<V> getIfPresent(K key)

Get value as Optional, distinguishing null from absent 以 Optional 形式获取值，区分 null 和不存在

Returns:

• null - key not present in cache
• Optional.empty() - key present with null value
• Optional.of(value) - key present with non-null value

Specified by:

getIfPresent in interface Cache<K,V>

Parameters:

key - the key | 键

Returns:

Optional containing value, empty Optional for cached null, or null if not present

getAll

public Map<K,V> getAll(Iterable<? extends K> keys)

Description copied from interface: Cache

Get all values for given keys, returns only existing entries 批量获取，仅返回存在的条目

Specified by:

getAll in interface Cache<K,V>

Parameters:

keys - the keys | 键集合

Returns:

map of existing entries | 存在的条目 Map

getAll

public Map<K,V> getAll(Iterable<? extends K> keys,
 Function<? super Set<? extends K>, ? extends Map<K,V>> loader)

Description copied from interface: Cache

Get all values, load missing keys using loader 批量获取，缺失的键通过 loader 加载

Specified by:

getAll in interface Cache<K,V>

Parameters:

keys - the keys | 键集合

loader - the batch loader function | 批量加载函数

Returns:

map of all entries | 所有条目 Map

put

public void put(K key,
 V value)

Description copied from interface: Cache

Put a key-value pair into cache 放入键值对

Specified by:

put in interface Cache<K,V>

Parameters:

key - the key | 键

value - the value | 值

putAll

public void putAll(Map<? extends K, ? extends V> map)

Description copied from interface: Cache

Put all key-value pairs into cache 批量放入

Specified by:

putAll in interface Cache<K,V>

Parameters:

map - the key-value pairs | 键值对 Map

putIfAbsent

public boolean putIfAbsent(K key,
 V value)

Description copied from interface: Cache

Put if the key is absent, returns true if successful 不存在时放入，成功返回 true

Specified by:

putIfAbsent in interface Cache<K,V>

Parameters:

key - the key | 键

value - the value | 值

Returns:

true if put successfully | 成功放入返回 true

putWithTtl

public void putWithTtl(K key,
 V value,
 Duration ttl)

Description copied from interface: Cache

Put a key-value pair with custom TTL (overrides default expiration) 放入键值对并指定自定义 TTL（覆盖默认过期时间）

Specified by:

putWithTtl in interface Cache<K,V>

Parameters:

key - the key | 键

value - the value | 值

ttl - the time-to-live for this entry | 此条目的存活时间

putAllWithTtl

public void putAllWithTtl(Map<? extends K, ? extends V> map,
 Duration ttl)

Description copied from interface: Cache

Put all entries with custom TTL 批量放入并指定自定义 TTL

Specified by:

putAllWithTtl in interface Cache<K,V>

Parameters:

map - the key-value pairs | 键值对 Map

ttl - the time-to-live for all entries | 所有条目的存活时间

putIfAbsentWithTtl

public boolean putIfAbsentWithTtl(K key,
 V value,
 Duration ttl)

Description copied from interface: Cache

Put if absent with custom TTL 不存在时放入并指定自定义 TTL

Specified by:

putIfAbsentWithTtl in interface Cache<K,V>

Parameters:

key - the key | 键

value - the value | 值

ttl - the time-to-live | 存活时间

Returns:

true if put successfully | 成功放入返回 true

invalidate

public void invalidate(K key)

Description copied from interface: Cache

Invalidate a single key 使单个键失效

Specified by:

invalidate in interface Cache<K,V>

Parameters:

key - the key to invalidate | 要失效的键

invalidateAll

public void invalidateAll(Iterable<? extends K> keys)

Description copied from interface: Cache

Invalidate multiple keys 批量失效

Specified by:

invalidateAll in interface Cache<K,V>

Parameters:

keys - the keys to invalidate | 要失效的键集合

invalidateAll

public void invalidateAll()

Description copied from interface: Cache

Invalidate all entries 清空所有缓存

Specified by:

invalidateAll in interface Cache<K,V>

containsKey

public boolean containsKey(K key)

Description copied from interface: Cache

Check if key exists 检查键是否存在

Specified by:

containsKey in interface Cache<K,V>

Parameters:

key - the key | 键

Returns:

true if exists | 存在返回 true

containsNullValue

public boolean containsNullValue(K key)

Check if the key is present with a null value 检查键是否存在且值为 null

Parameters:

key - the key | 键

Returns:

true if key is present with null value | 键存在且值为 null 返回 true

size

public long size()

Description copied from interface: Cache

Get exact entry count (may be slow) 获取精确条目数（可能较慢）

Specified by:

size in interface Cache<K,V>

Returns:

entry count | 条目数

estimatedSize

public long estimatedSize()

Description copied from interface: Cache

Get estimated entry count (fast) 获取估算条目数（快速）

Specified by:

estimatedSize in interface Cache<K,V>

Returns:

estimated count | 估算数量

keys

public Set<K> keys()

Description copied from interface: Cache

Get snapshot of all keys 获取所有键的快照

Specified by:

keys in interface Cache<K,V>

Returns:

set of keys | 键集合

values

public Collection<V> values()

Description copied from interface: Cache

Get snapshot of all values 获取所有值的快照

Specified by:

values in interface Cache<K,V>

Returns:

collection of values | 值集合

entries

public Set<Map.Entry<K,V>> entries()

Description copied from interface: Cache

Get snapshot of all entries 获取所有条目的快照

Specified by:

entries in interface Cache<K,V>

Returns:

set of entries | 条目集合

asMap

public ConcurrentMap<K,V> asMap()

Description copied from interface: Cache

Get a concurrent map view of this cache 获取 ConcurrentMap 视图

Specified by:

asMap in interface Cache<K,V>

Returns:

concurrent map view | ConcurrentMap 视图

stats

public CacheStats stats()

Description copied from interface: Cache

Get cache statistics 获取缓存统计信息

Specified by:

stats in interface Cache<K,V>

Returns:

cache statistics | 缓存统计

metrics

public CacheMetrics metrics()

Description copied from interface: Cache

Get detailed cache metrics with latency percentiles 获取带延迟百分位数的详细缓存指标

Specified by:

metrics in interface Cache<K,V>

Returns:

cache metrics or null if not enabled | 缓存指标，未启用则返回 null

cleanUp

public void cleanUp()

Description copied from interface: Cache

Perform cleanup (expired entries, etc.) 执行清理（过期条目等）

Specified by:

cleanUp in interface Cache<K,V>

async

public AsyncCache<K,V> async()

Description copied from interface: Cache

Get async view of this cache 获取异步视图

Specified by:

async in interface Cache<K,V>

Returns:

async cache view | 异步缓存视图

name

public String name()

Description copied from interface: Cache

Get cache name 获取缓存名称

Specified by:

name in interface Cache<K,V>

Returns:

cache name | 缓存名称