线程安全缓存ConcurrentLinkedHashMap，Kotlin

灰太狼 2023-10-15 15:08 21阅读 0赞

### **线程安全缓存ConcurrentLinkedHashMap，Kotlin** ###

[LinkedHashMap实现LRU缓存cache机制，Kotlin\_zhangphil的博客-CSDN博客\* \* 基于Java LinkedList,实现Android大数据缓存策略 \* 作者：Zhang Phil \* 原文出处：http://blog.csdn.net/zhangphil \* \* 实现原理：原理的模型认为：在LinkedList的头部元素是最旧的缓存数据，在L\_android大数据缓存。一句话概括的说：两者最大的不同就是，HashMap不保证put进去的数据的顺序；例如，假如在HashMap中依次、顺序添加元素：1，2，3，4，5，在遍历HashMap时输出的顺。![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/132604797][LinkedHashMap_LRU_cache_Kotlin_zhangphil_-CSDN_ _ _Java LinkedList_Android_ _ _Zhang Phil _ _http_blog.csdn.net_zhangphil _ _ _LinkedList_L_android_HashMap_put_HashMap_1_2_3_4_5_HashMap_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_132604797]上文利用LinkedHashMap固有特性发展出一种简洁的LRU缓存实现，在一些轻量级、小型LRU业务场景中，可以轻快构建出一个缓存模块，但并不是线程安全的。Google借鉴LinkedHashMap思想**，**发展出线程安全的ConcurrentLinkedHashMap缓存实现。

[GitHub - ben-manes/concurrentlinkedhashmap: A ConcurrentLinkedHashMap for JavaA ConcurrentLinkedHashMap for Java. Contribute to ben-manes/concurrentlinkedhashmap development by creating an account on GitHub.![icon-default.png?t=N7T8][icon-default.png_t_N7T8]https://github.com/ben-manes/concurrentlinkedhashmap][GitHub - ben-manes_concurrentlinkedhashmap_ A ConcurrentLinkedHashMap for JavaA ConcurrentLinkedHashMap for Java. Contribute to ben-manes_concurrentlinkedhashmap development by creating an account on GitHub._icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_github.com_ben-manes_concurrentlinkedhashmap]

引入：

<dependency>
                <groupId>com.googlecode.concurrentlinkedhashmap</groupId>
                <artifactId>concurrentlinkedhashmap-lru</artifactId>
                <version>1.4.2</version>
            </dependency>

import com.googlecode.concurrentlinkedhashmap.ConcurrentLinkedHashMap
    import com.googlecode.concurrentlinkedhashmap.EvictionListener
    
    fun main(args: Array<String>) {
        val CACHE_LIMIT = 3L
    
        val map = ConcurrentLinkedHashMap.Builder<Int, String>()
            .maximumWeightedCapacity(CACHE_LIMIT)
            .listener(object : EvictionListener<Int, String> {
                //当LRU缓存的头部元素删除时候回调。
                override fun onEviction(p0: Int?, p1: String?) {
                    println("onEviction $p0-$p1")
                }
            })
            .build()
    
        map[1] = "a"
        map[2] = "b"
        map[3] = "c"
        println("- $map")
    
        map[4] = "d"
        println("-- $map")
    
        println(map[3])
        println("--- $map")
    }

> \- \{1=a, 2=b, 3=c\}  
> onEviction 1-a  
> \-- \{2=b, 3=c, 4=d\}  
> c  
> \--- \{2=b, 3=c, 4=d\}

ConcurrentLinkedHashMap和LinkedHashMap有一个不同点是，LinkedHashMap在访问存储的元素后，会将被访问的元素移动到最尾部（设置访问order=true），而ConcurrentLinkedHashMap则没有这步操作，元素即便被访问，仍然保持原先顺序。

不管ConcurrentLinkedHashMap或者LinkedHashMap实现的缓存，比较适合小型、轻量级的缓存系统，如果是大型、功能要求复杂、要求高性能的业务场景，谷歌建议使用caffeine：

[GitHub - ben-manes/caffeine: A high performance caching library for JavaA high performance caching library for Java. Contribute to ben-manes/caffeine development by creating an account on GitHub.![icon-default.png?t=N7T8][icon-default.png_t_N7T8]https://github.com/ben-manes/caffeine][GitHub - ben-manes_caffeine_ A high performance caching library for JavaA high performance caching library for Java. Contribute to ben-manes_caffeine development by creating an account on GitHub._icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_github.com_ben-manes_caffeine]caffeine是一种更现代化的、高性能、功能强大的LRU缓存框架。

[高性能内存缓存框架Caffeine，Java\_zhangphil的博客-CSDN博客高性能内存缓存框架Caffeine，Java。\_内存缓存框架![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/126908710][Caffeine_Java_zhangphil_-CSDN_Caffeine_Java_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_126908710]

[favicon32.ico]: https://g.csdnimg.cn/static/logo/favicon32.ico
[LinkedHashMap_LRU_cache_Kotlin_zhangphil_-CSDN_ _ _Java LinkedList_Android_ _ _Zhang Phil _ _http_blog.csdn.net_zhangphil _ _ _LinkedList_L_android_HashMap_put_HashMap_1_2_3_4_5_HashMap_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_132604797]: https://blog.csdn.net/zhangphil/article/details/132604797
[icon-default.png_t_N7T8]: https://csdnimg.cn/release/blog_editor_html/release2.3.6/ckeditor/plugins/CsdnLink/icons/icon-default.png?t=N7T8
[GitHub - ben-manes_concurrentlinkedhashmap_ A ConcurrentLinkedHashMap for JavaA ConcurrentLinkedHashMap for Java. Contribute to ben-manes_concurrentlinkedhashmap development by creating an account on GitHub._icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_github.com_ben-manes_concurrentlinkedhashmap]: https://github.com/ben-manes/concurrentlinkedhashmap
[GitHub - ben-manes_caffeine_ A high performance caching library for JavaA high performance caching library for Java. Contribute to ben-manes_caffeine development by creating an account on GitHub._icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_github.com_ben-manes_caffeine]: https://github.com/ben-manes/caffeine
[Caffeine_Java_zhangphil_-CSDN_Caffeine_Java_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_126908710]: https://blog.csdn.net/zhangphil/article/details/126908710