Spring 的 @EnableCaching 注解

更新时间：2022-08-14 19:29:48

@EnableCaching注解是spring framework中的注解驱动的缓存管理功能。自spring版本3.1起加入了该注解。如果你使用了这个注解，那么你就不需要在XML文件中配置cache manager了。

当你在配置类(@Configuration)上使用@EnableCaching注解时，会触发一个post processor，这会扫描每一个spring bean，查看是否已经存在注解对应的缓存。如果找到了，就会自动创建一个代理拦截方法调用，使用缓存的bean执行处理。

如果你对缓存感兴趣并想了解更多，请阅读spring caching. 本文会帮助你了解如何使用@EnableCaching注解。

接下来的例子演示了@EnableCaching的用法。在代码中，我缓存了Book类找那个的方法。

importorg.springframework.cache.annotation.Cacheable;


public class Book{

   @Cacheable(value="simpleCache")
   public String getBook(int id){
       System.out.println("Method cached");
       if(id==1){
           return "Book 1";
      }else{
           return "Book 2";
      }
  }
}



importorg.springframework.cache.CacheManager;
importorg.springframework.cache.annotation.EnableCaching;
importorg.springframework.cache.concurrent.ConcurrentMapCache;
importorg.springframework.cache.support.SimpleCacheManager;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;

importjava.util.Arrays;

@Configuration
@EnableCaching
public class CachingConfig{

   @Bean
   public Book book(){
       return new Book();
  }

   @Bean
   public CacheManager cacheManager(){
       SimpleCacheManager simpleCacheManager = new SimpleCacheManager();
       simpleCacheManager.setCaches(Arrays.asList(new ConcurrentMapCache("simpleCache")));
       return simpleCacheManager;
  }

}

importorg.springframework.context.annotation.AnnotationConfigApplicationContext;

public class EnableCachingAnnotationExample{

   public static void main(String[] args) {
       AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
       context.register(CachingConfig.class);
       context.refresh();

       Bookbook=context.getBean(Book.class);
       System.out.println(book.getBook(1));
       System.out.println(book.getBook(1));
       System.out.println(book.getBook(2));

       context.close();
  }
}

上面的java config和下面的xml配置文件是等效的：

<beans>
    <cache:annotation-driven/>
    <bean id ="book" class = "Book"/>
    <bean id ="cacheManager" class = "org.springframework.cache.support.SimpleCacheManager">
        <property name = "caches">
            <set>
                <bean class = "org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean">
                    <property name = "name" value = "sampleCache"/>
                </bean>
            </set>
        </property>
    </bean>
</beans>

测试类

importorg.springframework.context.annotation.AnnotationConfigApplicationContext;

public class EnableCachingAnnotationExample{
   public static void main(String[] args) {
       AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(); 
       ctx.register(CachingConfig.class);
       ctx.refresh();
       Bookbook ctx.getBean(Book.class);        
       // calling getBook method first time.
       System.out.println(book.getBook(1));
       // calling getBook method second time. This time, method will not
       // execute.
       System.out.println(book.getBook(1));
       // calling getBook method third time with different value.
       System.out.println(book.getBook(2));
       ctx.close();
  }
}

输出：

Method executed..
Book 1
Book 1
Method executed..
Book 2

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Spring 的 @EnableCaching 注解

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