Type Parameters:: V - the type of values | 值类型

Functional Interface:: This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface public interface ValueWeigher<V>

Value Weigher - Calculate weight of cache entries for memory-based eviction 值权重计算器 - 计算缓存条目权重用于基于内存的淘汰

Used to calculate the weight of cache values for memory-aware caching. When cache reaches maximum weight, entries are evicted based on their weight.

用于计算缓存值的权重以实现内存感知的缓存。当缓存达到最大权重时，根据权重淘汰条目。

Features | 主要功能:

Custom weight calculation - 自定义权重计算
Memory-based eviction support - 基于内存的淘汰支持
Built-in weighers for common types - 常见类型的内置权重计算器

Usage Examples | 使用示例:

// Fixed weight per entry - 每个条目固定权重
ValueWeigher<String> fixed = ValueWeigher.fixed(1);

// String length as weight - 字符串长度作为权重
ValueWeigher<String> stringWeigher = ValueWeigher.stringLength();

// Collection size as weight - 集合大小作为权重
ValueWeigher<List<User>> listWeigher = ValueWeigher.collectionSize();

// Custom weigher - 自定义权重计算器
ValueWeigher<User> userWeigher = user -> user.getDataSize();

// Use in cache config - 在缓存配置中使用
Cache<String, User> cache = OpenCache.builder()
    .maximumWeight(1_000_000)  // 1MB
    .weigher(user -> user.getSerializedSize())
    .build();

Security | 安全性:

Thread-safe: Depends on implementation - 线程安全: 取决于实现
Weight must be non-negative - 权重必须非负

Since:

JDK 25, opencode-base-cache V1.0.0

Author:

Leon Soo www.LeonSoo.com

See Also:

Nested Class Summary

Nested Classes

Modifier and Type

Interface

Description

static interface

ValueWeigher.EntryWeigher<K,V>

Entry weigher interface for key-value pairs 键值对的条目权重计算器接口
Method Summary

Modifier and Type

Method

Description

static <V> ValueWeigher<V>

arrayLength()

Create a weigher using array length 创建使用数组长度的权重计算器

default ValueWeigher<V>

bounded(long minWeight, long maxWeight)

Create a weigher bounded between min and max 创建在最小和最大之间的权重计算器

static ValueWeigher<byte[]>

byteArrayLength()

Create a weigher using byte array length 创建使用字节数组长度的权重计算器

static <V extends Collection<?>> ValueWeigher<V>

collectionSize()

Create a weigher using collection size 创建使用集合大小的权重计算器

static <K,V> ValueWeigher.EntryWeigher<K,V>

combined(ValueWeigher<K> keyWeigher, ValueWeigher<V> valueWeigher)

Create a weigher that considers both key and value 创建同时考虑键和值的权重计算器

static <V> ValueWeigher<V>

estimatedMemory()

Create a weigher that estimates memory size for common types 创建估算常见类型内存大小的权重计算器

static <V> ValueWeigher<V>

fixed(long weight)

Create a weigher with fixed weight per entry 创建每个条目固定权重的权重计算器

static <V extends Map<?,?>> ValueWeigher<V>

mapSize()

Create a weigher using map size 创建使用 Map 大小的权重计算器

static ValueWeigher<String>

stringLength()

Create a weigher using string length 创建使用字符串长度的权重计算器

default ValueWeigher<V>

times(long multiplier)

Create a weigher that applies a multiplier 创建应用乘数的权重计算器

long

weigh(V value)

Calculate the weight of a value 计算值的权重

default ValueWeigher<V>

withMaximum(long maxWeight)

Create a weigher with maximum weight 创建带最大权重的权重计算器

default ValueWeigher<V>

withMinimum(long minWeight)

Create a weigher with minimum weight 创建带最小权重的权重计算器

Method Details
- weigh
  
  long weigh(V value)
  
  Calculate the weight of a value 计算值的权重
  
  Parameters:
  
  value - the value to weigh | 要计算权重的值
  
  Returns:
  
  the weight (must be non-negative) | 权重（必须非负）
- fixed
  
  static <V> ValueWeigher<V> fixed(long weight)
  
  Create a weigher with fixed weight per entry 创建每个条目固定权重的权重计算器
  
  Type Parameters:
  
  V - the value type | 值类型
  
  Parameters:
  
  weight - the fixed weight | 固定权重
  
  Returns:
  
  the weigher | 权重计算器
- stringLength
  
  static ValueWeigher<String> stringLength()
  
  Create a weigher using string length 创建使用字符串长度的权重计算器
  
  Returns:
  
  the weigher | 权重计算器
- byteArrayLength
  
  static ValueWeigher<byte[]> byteArrayLength()
  
  Create a weigher using byte array length 创建使用字节数组长度的权重计算器
  
  Returns:
  
  the weigher | 权重计算器
- collectionSize
  
  static <V extends Collection<?>> ValueWeigher<V> collectionSize()
  
  Create a weigher using collection size 创建使用集合大小的权重计算器
  
  Type Parameters:
  
  V - the collection type | 集合类型
  
  Returns:
  
  the weigher | 权重计算器
- mapSize
  
  static <V extends Map<?,?>> ValueWeigher<V> mapSize()
  
  Create a weigher using map size 创建使用 Map 大小的权重计算器
  
  Type Parameters:
  
  V - the map type | Map 类型
  
  Returns:
  
  the weigher | 权重计算器
- arrayLength
  
  static <V> ValueWeigher<V> arrayLength()
  
  Create a weigher using array length 创建使用数组长度的权重计算器
  
  Type Parameters:
  
  V - the array type | 数组类型
  
  Returns:
  
  the weigher | 权重计算器
- estimatedMemory
  static <V> ValueWeigher<V> estimatedMemory()
  
  Create a weigher that estimates memory size for common types 创建估算常见类型内存大小的权重计算器
  Estimates memory usage based on type:
  
  String: length * 2 + 40 (approx char array + header)
  
  byte[]: length + 16 (array + header)
  
  Collection: size * 8 + 40 (references + header)
  
  Map: size * 16 + 40 (key + value refs + header)
  
  Other: 40 (minimum object overhead)
  
  Type Parameters:
  
  V - the value type | 值类型
  
  Returns:
  
  the weigher | 权重计算器
- times
  
  default ValueWeigher<V> times(long multiplier)
  
  Create a weigher that applies a multiplier 创建应用乘数的权重计算器
  
  Parameters:
  
  multiplier - the multiplier | 乘数
  
  Returns:
  
  the scaled weigher | 缩放后的权重计算器
- withMinimum
  
  default ValueWeigher<V> withMinimum(long minWeight)
  
  Create a weigher with minimum weight 创建带最小权重的权重计算器
  
  Parameters:
  
  minWeight - the minimum weight | 最小权重
  
  Returns:
  
  the bounded weigher | 带边界的权重计算器
- withMaximum
  
  default ValueWeigher<V> withMaximum(long maxWeight)
  
  Create a weigher with maximum weight 创建带最大权重的权重计算器
  
  Parameters:
  
  maxWeight - the maximum weight | 最大权重
  
  Returns:
  
  the bounded weigher | 带边界的权重计算器
- bounded
  
  default ValueWeigher<V> bounded(long minWeight, long maxWeight)
  
  Create a weigher bounded between min and max 创建在最小和最大之间的权重计算器
  
  Parameters:
  
  minWeight - the minimum weight | 最小权重
  
  maxWeight - the maximum weight | 最大权重
  
  Returns:
  
  the bounded weigher | 带边界的权重计算器
- combined
  
  static <K,V> ValueWeigher.EntryWeigher<K,V> combined(ValueWeigher<K> keyWeigher, ValueWeigher<V> valueWeigher)
  
  Create a weigher that considers both key and value 创建同时考虑键和值的权重计算器
  
  Type Parameters:
  
  K - the key type | 键类型
  
  V - the value type | 值类型
  
  Parameters:
  
  keyWeigher - the key weigher | 键权重计算器
  
  valueWeigher - the value weigher | 值权重计算器
  
  Returns:
  
  the combined weigher | 组合的权重计算器

Interface ValueWeigher<V>

Nested Class Summary

Method Summary

Method Details

weigh

fixed

stringLength

byteArrayLength

collectionSize

mapSize

arrayLength

estimatedMemory

times

withMinimum

withMaximum

bounded

combined