Spring
使用 spring 中的缓存。
例子
- User.java
用于测试的实体。
public class User {
private Long id;
private String name;
//Getter & Setter
//toString()
}
- UserService.java
用户服务类接口。
public interface UserService {
/**
* 获取用户
* @param id 标识
* @return 用户
*/
User getUser(Long id);
/**
* 删除用户
* @param id 标识
*/
void deleteUser(Long id);
/**
* 更新用户
* @param user 用户
* @return 用户
*/
User updateUser(User user);
/**
* 清除缓存
*/
void clearCache();
}
- UserServiceImpl.java
@Service
public class UserServiceImpl implements UserService {
/**
* Cacheable triggers cache population
*/
@Override
@Cacheable(value = "user", key = "'user_id_' + #id")
public User getUser(Long id) {
System.out.println("get user: " + id);
User user = new User();
user.setId(id);
return user;
}
@Override
@CacheEvict(value = "user", key = "'user_id_'+#id")
public void deleteUser(Long id) {
System.out.println("delete user: " + id);
}
/**
* updated without interfering with the method execution
* - 将返回的结果,放入缓存
*/
@Override
@CachePut(value = "user", key = "'user_id_'+#user.getId()")
public User updateUser(User user) {
System.out.println("update user: " + user);
user.setName("cachePut update");
return user;
}
@Override
@CacheEvict(value = "user", allEntries = true)
public void clearCache() {
System.out.println("clear all user cache");
}
}
- applicationContext-cache.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:cache="http://www.springframework.org/schema/cache"
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache.xsd">
<!-- Activates annotation-based bean configuration -->
<context:annotation-config/>
<!-- Scans for application @Components to deploy -->
<context:component-scan base-package="com.github.houbb.redis.learn.spring.cache"/>
<cache:annotation-driven/>
<!-- spring自己的缓存管理器，这里定义了缓存位置名称 ，即注解中的value -->
<bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">
<property name="caches">
<bean class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"
p:name="user"/>
</property>
</bean>
</beans>
测试
- 读取
@ContextConfiguration(locations = {"classpath:applicationContext-cache.xml"})
@SpringJUnitConfig
public class UserServiceTest {
@Autowired
private UserService userService;
/**
*
* Method: getUser(Long id)
*
*/
@Test
public void getUserTest() throws Exception {
User user1 = userService.getUser(1L);
User user2 =userService.getUser(1L);
System.out.println(user1);
System.out.println(user2);
}
}
日志
...
get user: 1
User{id=1, name='null'}
User{id=1, name='null'}
可见，第二次查询时走的实际上是缓存。
自己实现
思路
- 定义注解
模仿 spring 注解。
- 定义拦截器
基于上述注解的对应实现。
