Detailed explanation of the LRU cache framework in the Java class library

Detailed explanation of the LRU cache framework in the Java class library LRU (Least Recently Used) is a common cache algorithm that is used to manage data items in cache.In the Java class library, we can use the existing LRU cache framework to easily implement the cache management function and improve the performance and response speed of the program. 1. The principle of LRU cache The LRU cache is based on the principle of "minimum use recently", that is, when the cache space is full, it will select the recently used data item to eliminate according to the frequency of the data item, so that the space can be cached to cache new data items.This can ensure that the commonly used data items in the cache have been in memory and improve access efficiency. 2. LRU cache framework in the Java class library In the Java class library, many third -party libraries and open source projects provide the implementation of the LRU cache.Among them, more commonly used and powerful are EHCACHE, Guava Cache, and Caffeine. 1. Ehcache EHCACHE is a popular Java cache framework that provides rich features and configuration options, including the LRU cache strategy.With EHCACHE, we can simply configure a LRU cache instance and specify parameters such as the maximum capacity and expiration time of the cache. Below is an example code that uses EHCACHE to create LRU cache: CacheManager cacheManager = CacheManagerBuilder.newCacheManagerBuilder() .withCache("myCache", CacheConfigurationBuilder.newCacheConfigurationBuilder(Integer.class, String.class, ResourcePoolsBuilder.heap(10)) .build()) .build(true); Cache<Integer, String> cache = cacheManager.getCache("myCache", Integer.class, String.class); cache.put(1, "foo"); cache.put(2, "bar"); String value = cache.get(1); System.out.println (value); // Output: FOO cache.put (3, "baz"); // Add the third element and eliminate the longest unused element value = cache.get(2); System.out.println (value); // Output: null, elements have been eliminated cacheManager.close(); 2. Guava Cache Guava Cache is a powerful cache framework provided by Google, and also supports the LRU cache strategy.Guava Cache provides a simple and easy -to -use API, which can easily create and manage the LRU cache. Below is an example code that uses Guava Cache to create LRU cache: LoadingCache<Integer, String> cache = CacheBuilder.newBuilder() .maximumsize (10) // Specify the maximum capacity of the cache .build(new CacheLoader<Integer, String>() { public String load(Integer key) { // When there is no value corresponding to the key in the cache, you can define the logic of generating new value here. return "Value-" + key; } }); cache.put(1, "foo"); cache.put(2, "bar"); String value = cache.get(1); System.out.println (value); // Output: FOO cache.put (3, "baz"); // Add the third element and eliminate the longest unused element value = cache.getIfPresent(2); System.out.println (value); // Output: null, elements have been eliminated 3. Caffeine Caffeine is a high -performance Java cache library that also supports the LRU cache strategy.Caffeine provides a variety of configuration options that can customize cache behaviors according to specific needs. Below is a sample code using Caffeine to create LRU cache: LoadingCache<Integer, String> cache = Caffeine.newBuilder() .maximumsize (10) // Specify the maximum capacity of the cache .build(new CacheLoader<Integer, String>() { public String load(Integer key) { // When there is no value corresponding to the key in the cache, you can define the logic of generating new value here. return "Value-" + key; } }); cache.put(1, "foo"); cache.put(2, "bar"); String value = cache.get(1); System.out.println (value); // Output: FOO cache.put (3, "baz"); // Add the third element and eliminate the longest unused element value = cache.getIfPresent(2); System.out.println (value); // Output: null, elements have been eliminated The above are simple examples of using EHCACHE, Guava Cache and Caffeine frameworks to create LRU cache. They all provide more options and functions, which can be configured and used according to specific needs. Summarize The LRU cache is an effective way to improve program performance. By selecting the latest data that has been recently used for elimination, it can retain commonly used data items in memory and increase access speed.In the Java class library, we can use existing LRU cache frameworks such as EHCACHE, Guava Cache, and Caffeine to simplify the implementation of cache management.According to specific needs, select a suitable framework and configure and use it.