[SpringBoot] Use Spring Cache to efficiently process cached data

Table of Contents

1. Brief description of Spring Cache

2. Common annotations for Spring Cache

3. @Cacheable annotation

4. @CacheEvict annotation

1. Brief description of Spring Cache

Spring Cache is a caching abstraction mechanism provided by the Spring framework to simplify caching operations in applications. It caches the return value of the method. When the same method is called next time, if the parameters passed in are the same as the previous call, the result can be obtained directly from the cache without executing the code in the method body. This improves System performance and responsiveness.

The main features of Spring Cache are as follows:

  1. Declarative caching: Declare caching behavior by adding annotations on methods, such as @Cacheable, @CachePut, @CacheEvict, etc., without manually writing caching code.
  2. Multiple cache support: Spring Cache provides support for multiple cache technologies, including memory cache, Redis, Ehcache, Guava Cache, etc. You can choose the appropriate cache implementation according to your needs.
  3. Cache policy configuration: Cache policies can be configured through configuration files or programmatically, including cache expiration time, cache elimination policy, etc.
  4. Flexible application of annotations: By adding different annotations to methods, operations such as cache reading, updating, and clearing can be realized, and flexibly configured according to business needs.
  5. Automatic proxying of cache aspects: Spring Cache uses AOP technology and uses proxy mode to intercept before and after method execution and automatically handle cache-related operations without intrusion into business code.

The steps to use Spring Cache are as follows:

  1. Configure the cache manager in the Spring configuration file and specify the specific cache implementation.
  2. Add corresponding annotations on the methods that need to be cached, such as @Cacheable means reading the cache, @CachePut means updating the cache, and @CacheEvict means clearing the cache.
  3. Configure cache policies as needed, such as cache expiration time, cache elimination policy, etc.

In general, Spring Cache provides a simple and convenient cache abstraction mechanism, allowing developers to use cache more conveniently to improve system performance, and has the characteristics of flexible annotation application and support for multiple caching technologies.

2. Spring Cache common annotations

Spring Cache provides several commonly used annotations for declaring cache behavior:

  1. @Cacheable: Marked on a method, indicating that the return value of the method can be cached. When the method is called, it will first check whether the corresponding result exists in the cache. If it exists, the value in the cache will be returned directly. If it does not exist, the method body will be executed and the return value will be cached.

  2. @CachePut: Marked on a method, indicating that the return value of the method will be cached. Unlike @Cacheable, @CachePut will execute the method body every time and cache the return value. It is typically used for operations that update caches.

  3. @CacheEvict: Marked on the method, indicating that the method will clear the specified cache item. You can specify the cache items to clear by setting different attributes, such as specifying to clear cache items with specific keys through the key attribute, and specifying to clear all cache items through the allEntries attribute.

  4. @Caching: used to combine multiple caching operations on a method. Annotations such as @Cacheable, @CachePut and @CacheEvict can be used at the same time.

  5. @CacheConfig: Marked on the class, used to specify the cache-related configuration of all methods in the class, including cache name, cache manager, etc. Can reduce repeated annotation configuration.

These annotations provide a declarative way to manage the cache. By adding corresponding annotations to the methods, operations such as reading, updating, and clearing the cache can be easily implemented. At the same time, Spring Cache also supports the use of SpEL expressions to dynamically specify cache keys and conditions. Developers can choose appropriate annotations to configure caching behavior based on specific business needs.

3. @Cacheable annotation

The @Cacheable annotation is one of the most commonly used annotations in SpringCache, used to mark that the return value of a method can be cached. The specific usage is as follows:

  1. Add the @Cacheable annotation on methods that need to be cached.
@Cacheable(value = "cacheName", key = "#param")
public ReturnType methodName(ParameterType param) {
    // method body
}

  1. The value attribute of the @Cacheable annotation specifies the name of the cache, which can be customized according to actual needs. If not specified, the class name of the method is used as the cache name by default.

  2. The key attribute of the @Cacheable annotation can specify the cache key, which is used to identify the uniqueness of the cache item. SpEL expressions are usually used to dynamically generate cache keys, which can reference method parameters, return values, etc.

  3. When a method marked with the @Cacheable annotation is called, the corresponding cache item will first be searched in the cache. If the corresponding key-value pair exists in the cache, the value in the cache will be returned directly and the method body will not be executed. If the corresponding key-value pair does not exist in the cache, the method body is executed and the returned result is cached for next use.

It should be noted that when using the @Cacheable annotation, you should ensure that the return value of the method is serializable, because the cache needs to serialize and store the return value. If the return value is not serializable, consider using other caching techniques or custom serialization.

The @Cacheable annotation also supports other attributes, such as condition, unless, sync, etc., to further control the behavior of the cache. Can be configured according to specific needs.

In summary, the @Cacheable annotation can easily cache the return value of the method and improve the performance and response speed of the system.

4. @CacheEvict annotation

The @CacheEvict annotation is one of the annotations in SpringCache and is used to clear specified cache items. The specific usage is as follows:

  1. Add the @CacheEvict annotation on the method that needs to clear the cache.
@CacheEvict(value="cacheName", key="#param")
public void methodName(ParameterType param) {
    // method body
}

  1. The value attribute of the @CacheEvict annotation specifies the cache name to be cleared, which can be customized according to actual needs. If not specified, the class name of the method is used as the cache name by default.

  2. The key attribute of the @CacheEvict annotation can specify the key of the cache item to be cleared, and is used to identify the cache item to be cleared. SpEL expressions are usually used to dynamically generate cache keys, and the parameters and return values of the method can be referenced.

  3. When a method marked with the @CacheEvict annotation is called, the specified cache item will be cleared. You can further control the clearing behavior by setting other properties, such as clearing all entries in the cache through the allEntries property.

It should be noted that the @CacheEvict annotation will only clear the cache and will not return any results.

The @CacheEvict annotation also supports other attributes, such as condition, beforeInvocation, etc., to further control the conditions and timing of clearing the cache.

In summary, the @CacheEvict annotation is an annotation used to clear specified cache items. By adding this annotation to the method, the cache clearing operation can be easily performed.

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