Learn about Caffeine caching technology

Caffeine caching technology is an efficient, scalable and memory-friendly Java caching library. It was developed by Google and is widely used and proven within Google. Since being open sourced by Google in 2012, Caffeine has become a popular Java caching solution.

Caffeine's goal is to improve cache hit rate and performance, and support high concurrency scenarios. It does this by reducing memory consumption, locking time, and garbage collection overhead.

Compared with other Java cache libraries, Caffeine has the following features:

1. Zero-leak thread
   Caffeine uses the Java ConcurrentReferenceHashMap class to further enhance HashMap, making it better support concurrency access. Additionally, Caffeine avoids the memory leak issues seen in previous versions.
2. Quick Access
   Caffeine achieves fast access by using array and linked list data structures. When the number of cache items is small, it uses an array to store all cache items. When the number of cache items exceeds the array size, it uses a linked list to store the cache items. This approach reduces cache lookup time, thereby improving performance.
3. Easy to Expand
   One of the design goals of Caffeine is scalability. It allows developers to extend its functionality through plugins. For example, cache item expiration, cache item revocation, cache item decorator, etc.
4. Easy to operate
   Caffeine's API is easy to use and can be easily configured, tuned and managed.

If you want to try Caffeine, here are some steps:

1. Add Maven/Gradle dependency

Add Maven dependency as shown below :

<dependency>
    <groupId>com.github.ben-manes.caffeine</groupId>
    <artifactId>caffeine</artifactId>
    <version>2.8.8</version>
</dependency>

Add the Gradle dependency as follows:

implementation 'com.github.ben-manes.caffeine:caffeine:2.8.8'

2. Initialize the cache

Initialize the cache using the Caffeine factory method. For example, the following code snippet creates a cache object that caches up to 1000 key-value pairs.

Cache<String, Object> cache = Caffeine.newBuilder()
    .maximumSize(1000)
    .build();

3. Storing and retrieving cache items

Use the put method to store items and the get method to retrieve items. For example, the following code stores a string value and retrieves the value by cache key.

cache.put("key1", "value1");

Object value = cache.get("key1");

4. Clear the cache

If you need to clear the cache, you can use the invalidateAll method. For example, the following code clears all cached items.

cache.invalidateAll();

In short, Caffeine is an efficient Java caching library designed to improve cache hit rate and performance, and support high concurrency scenarios. It's simple to use and easy to extend, making it a great caching solution.

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