要实现一个 SQLiteCache 也是很简单的只需要创建一个 cacheManager Bean 即可

// 如果配置文件中 spring.cache.sqlite.enable = false 则不启用
@Bean("cacheManager")
@ConditionalOnProperty(name = ["spring.cache.sqlite.enable"], havingValue = "true", matchIfMissing = false)
fun cacheManager(sqliteMemoryConnection: Connection): CacheManager {
    // TODO 返回 CacheManager 
}

同样的还需要 SQLite 这里 SQLite 的 url 设置为 jdbc:sqlite::memory:

@Bean
fun sqliteMemoryConnection(): Connection {
    val dataSource = SQLiteDataSource()
    dataSource.url = url
    logger.info("SQLite cache 创建连接: $url")
    return dataSource.connection
}

配置代码

该代码仅仅作为整活使用

package io.github.zimoyin.ra3.config

import io.github.zimoyin.ra3.config.SQLiteCacheConfig.EvictionPolicy.*
import kotlinx.coroutines.*
import org.bouncycastle.asn1.x500.style.RFC4519Style.name
import org.slf4j.LoggerFactory
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty
import org.springframework.boot.context.properties.ConfigurationProperties
import org.springframework.cache.Cache
import org.springframework.cache.CacheManager
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.validation.annotation.Validated
import org.sqlite.SQLiteDataSource
import java.sql.Connection
import java.util.*
import java.util.concurrent.*
import java.util.concurrent.atomic.AtomicLong
import java.util.concurrent.locks.ReentrantReadWriteLock
import javax.sql.DataSource
import kotlin.math.log
import kotlin.time.Duration.Companion.minutes

@Configuration
@Validated
@ConfigurationProperties(prefix = "spring.cache.sqlite")
class SQLiteCacheConfig(
    var url: String = "jdbc:sqlite::memory:",
    var enable: Boolean = false,
    var tableCacheSize: Int = 100,
    var expirationMilliseconds: Long = 60000L,
    var evictionPolicy: EvictionPolicy = FIFO,
) {
    private val logger = LoggerFactory.getLogger(SQLiteCacheConfig::class.java)

    @Bean
    fun sqliteDataSource(): DataSource {
        val dataSource = SQLiteDataSource()
        dataSource.url = url
        logger.info("初始化 SQLiteCache 数据库地址: $url")
        return dataSource
    }

    @Bean("sqliteCacheManager")
    @ConditionalOnProperty(name = ["spring.cache.sqlite.enable"], havingValue = "true")
    fun cacheManager(sqliteDataSource: DataSource): CacheManager = SQLiteCacheManager(
        dataSource = sqliteDataSource,
        maxSize = tableCacheSize,
        expirationMs = expirationMilliseconds,
        evictionPolicy = evictionPolicy
    )

    enum class EvictionPolicy {
        /**
         * First In First Out (FIFO)
         */
        FIFO,

        /**
         * Least Recently Used (LRU)
         */
        LRU,

        /**
         * Least Frequently Used (LFU)
         */
        LFU
    }

    class SQLiteCacheManager(
        private val dataSource: DataSource,
        private val maxSize: Int,
        private val expirationMs: Long,
        private val evictionPolicy: EvictionPolicy,
    ) : CacheManager {
        private val cacheMap = ConcurrentHashMap<String, SQLiteCache>()
        private val logger = LoggerFactory.getLogger(SQLiteCacheManager::class.java)
        private val scope = CoroutineScope(SupervisorJob() + Dispatchers.IO)

        init {
            // 启动定时清理任务（首次延迟1分钟，之后每分钟执行）
            CoroutineScope(SupervisorJob() + Dispatchers.IO).launch {
                while (isActive) {
                    delay(1.minutes)
                    cleanupExpiredEntries()
                }
            }
            logger.info("初始化 SQLiteCacheManager: dataSource=$dataSource, maxSize=$maxSize, expirationMs=$expirationMs, evictionPolicy=$evictionPolicy")
        }

        override fun getCache(name: String): Cache {
            return cacheMap.computeIfAbsent(name) {
                SQLiteCache(
                    name = it,
                    dataSource = dataSource,
                    maxSize = maxSize,
                    expirationMs = expirationMs,
                    evictionPolicy = evictionPolicy
                ).also { cache ->
                    logger.info("创建缓存表 $name")
                    cache.initialize()
                }
            }
        }

        override fun getCacheNames(): MutableCollection<String> = cacheMap.keys

        private fun cleanupExpiredEntries() {
            cacheMap.values.forEach { cache ->
                try {
                    logger.debug("缓存表 ${cache.name} 命中率: ${cache.getHitRate()}")
                    cache.evictExpiredItems()
                } catch (e: Exception) {
                    logger.error("Error cleaning expired entries in cache ${cache.name}", e)
                }
            }
        }

        @Synchronized
        fun shutdown() {
            scope.cancel()
            cacheMap.values.forEach { it.close() }
        }
    }

    class SQLiteCache(
        private val name: String,
        val dataSource: DataSource,
        val maxSize: Int,
        val expirationMs: Long,
        val evictionPolicy: EvictionPolicy,
    ) : Cache {
        private val logger = LoggerFactory.getLogger(SQLiteCache::class.java)
        private val connection: Connection = dataSource.connection.apply {
            autoCommit = false
        }
        private val lock = ReentrantReadWriteLock()
        private val hitCount = AtomicLong()
        private val missCount = AtomicLong()

        fun initialize() {
            createTableIfNotExists()
            createIndexes()
        }

        fun close() {
            connection.close()
        }

        override fun getName(): String = name

        override fun getNativeCache(): Any = connection

        override fun get(key: Any): Cache.ValueWrapper? {
            return try {
                lock.readLock().lock()
                getInternal(key.toString()).also {
                    if (it != null) hitCount.incrementAndGet() else missCount.incrementAndGet()
                }
            } finally {
                lock.readLock().unlock()
            }
        }

        override fun <T : Any?> get(key: Any, type: Class<T>?): T? {
            return get(key)?.get() as? T
        }

        override fun <T : Any?> get(key: Any, valueLoader: Callable<T>): T {
            return try {
                lock.writeLock().lock()
                get(key)?.get() as? T ?: run {
                    val value = valueLoader.call()
                    put(key, value)
                    value
                }
            } finally {
                lock.writeLock().unlock()
            }
        }

        override fun put(key: Any, value: Any?) {
            try {
                lock.writeLock().lock()
                executeInTransaction {
                    evictIfNecessary()
                    upsertEntry(key.toString(), value)
                }
            } finally {
                lock.writeLock().unlock()
            }
        }

        override fun evict(key: Any) {
            executeInTransaction {
                deleteEntry(key.toString())
            }
        }

        override fun clear() {
            executeInTransaction {
                connection.createStatement().executeUpdate("DELETE FROM $name")
            }
        }

        fun getHitRate(): Double {
            val total = hitCount.get() + missCount.get()
            return if (total == 0L) 0.0 else hitCount.get().toDouble() / total
        }

        internal fun evictExpiredItems() {
            executeInTransaction {
                val currentTime = System.currentTimeMillis()
                connection.prepareStatement("DELETE FROM $name WHERE expires_at < ?").use { ps ->
                    ps.setLong(1, currentTime)
                    ps.executeUpdate()
                }
            }
        }

        private fun getInternal(key: String): Cache.ValueWrapper? {
            return connection.prepareStatement(
                "SELECT value, expires_at FROM $name WHERE key = ?"
            ).use { ps ->
                ps.setString(1, key)
                ps.executeQuery().use { rs ->
                    if (rs.next()) {
                        val expiresAt = rs.getLong("expires_at")
                        if (System.currentTimeMillis() > expiresAt) {
                            deleteEntry(key)
                            null
                        } else {
                            updateAccessMetrics(key)
                            Cache.ValueWrapper { rs.getObject("value") }
                        }
                    } else {
                        null
                    }
                }
            }
        }

        /**
         * 更新访问指标
         */
        private fun updateAccessMetrics(key: String) {
            when (evictionPolicy) {
                LRU -> updateLastAccessed(key)
                LFU -> incrementAccessCount(key)
                FIFO -> run { /*不需要更新*/ }
            }
        }

        private fun upsertEntry(key: String, value: Any?) {
            val now = System.currentTimeMillis()
            connection.prepareStatement(
                """
                INSERT INTO $name 
                (key, value, expires_at, created_at, last_accessed, access_count)
                VALUES (?, ?, ?, ?, ?, 1)
                ON CONFLICT(key) DO UPDATE SET
                    value = excluded.value,
                    expires_at = excluded.expires_at,
                    last_accessed = excluded.last_accessed,
                    access_count = access_count + 1
                """
            ).use { ps ->
                ps.setString(1, key)
                ps.setObject(2, value)
                ps.setLong(3, now + expirationMs)
                ps.setLong(4, now)
                ps.setLong(5, now)
                ps.executeUpdate()
            }
        }

        private fun deleteEntry(key: String) {
            connection.prepareStatement("DELETE FROM $name WHERE key = ?").use { ps ->
                ps.setString(1, key)
                ps.executeUpdate()
            }
        }

        private fun evictIfNecessary() {
            if (currentSize() >= maxSize) {
                when (evictionPolicy) {
                    FIFO -> evictByCreatedTime()
                    LRU -> evictByLastAccessed()
                    LFU -> evictByAccessCount()
                }
            }
        }

        private fun currentSize(): Int {
            return connection.createStatement().use { stmt ->
                stmt.executeQuery("SELECT COUNT(*) FROM $name ").use { rs ->
                    if (rs.next()) rs.getInt(1) else 0
                }
            }
        }

        private fun evictByCreatedTime() {
            evictOldest("created_at")
        }

        private fun evictByLastAccessed() {
            evictOldest("last_accessed")
        }

        private fun evictByAccessCount() {
            connection.createStatement().use { stmt ->
                stmt.executeQuery(
                    "SELECT key FROM $name ORDER BY access_count ASC, created_at ASC LIMIT 1"
                ).use { rs ->
                    if (rs.next()) deleteEntry(rs.getString(1))
                }
            }
        }

        private fun evictOldest(column: String) {
            connection.createStatement().use { stmt ->
                stmt.executeQuery(
                    "SELECT key FROM $name ORDER BY $column ASC LIMIT 1"
                ).use { rs ->
                    if (rs.next()) deleteEntry(rs.getString(1))
                }
            }
        }

        private fun updateLastAccessed(key: String) {
            connection.prepareStatement(
                "UPDATE $name SET last_accessed = ? WHERE key = ?"
            ).use { ps ->
                ps.setLong(1, System.currentTimeMillis())
                ps.setString(2, key)
                ps.executeUpdate()
            }
        }

        private fun incrementAccessCount(key: String) {
            connection.createStatement().executeUpdate(
                "UPDATE $name SET access_count = access_count + 1 WHERE key = '$key'"
            )
        }

        private fun createTableIfNotExists() {
            connection.createStatement().execute(
                """
                CREATE TABLE IF NOT EXISTS $name (
                    key TEXT PRIMARY KEY,
                    value BLOB,
                    expires_at INTEGER,
                    created_at INTEGER,
                    last_accessed INTEGER,
                    access_count INTEGER DEFAULT 0
                )
                """
            )
        }

        /**
         * 创建索引
         */
        private fun createIndexes() {
            arrayOf(
                "CREATE INDEX IF NOT EXISTS idx_${name}_expires ON $name (expires_at)",
                "CREATE INDEX IF NOT EXISTS idx_${name}_created ON $name (created_at)",
                "CREATE INDEX IF NOT EXISTS idx_${name}_last_access ON $name (last_accessed)",
                "CREATE INDEX IF NOT EXISTS idx_${name}_access_count ON $name (access_count)"
            ).forEach { indexSql ->
                connection.createStatement().execute(indexSql)
            }
        }

        /**
         * 执行在事务中运行的代码块，并返回结果。如果代码块执行成功，则提交事务；如果代码块执行失败，则回滚事务。
         */
        private inline fun <T> executeInTransaction(block: () -> T): T {
            return try {
                val result = block()
                connection.commit()
                result
            } catch (ex: Exception) {
                connection.rollback()
                throw ex
            }
        }
    }
}

配置文件

spring:
  cache:
    sqlite:
      enable: false
      expiration-milliseconds: 60000
      table-cache-size: 10000
      eviction-policy: lru