Spring实战之清除缓存操作示例

<?xml version="1.0" encoding="GBK"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:p="http://www.springframework.org/schema/p"
   xmlns:cache="http://www.springframework.org/schema/cache"
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
   http://www.springframework.org/schema/cache
   http://www.springframework.org/schema/cache/spring-cache-4.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-4.0.xsd">
   <context:component-scan
      base-package="org.crazyit.app.service" />
   <cache:annotation-driven
      cache-manager="cacheManager" />
   <!-- 配置EhCache的CacheManager 通过configLocation指定ehcache.xml文件的位置 -->
   <bean id="ehCacheManager"
      class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"
      p:configLocation="classpath:ehcache.xml" p:shared="false" />
   <!-- 配置基于EhCache的缓存管理器 并将EhCache的CacheManager注入该缓存管理器Bean -->
   <bean id="cacheManager"
      class="org.springframework.cache.ehcache.EhCacheCacheManager"
      p:cacheManager-ref="ehCacheManager">
   </bean>
</beans>

<?xml version="1.0" encoding="gbk"?>
<ehcache>
  <diskStore path="java.io.tmpdir" />
   <!-- 配置默认的缓存区 -->
  <defaultCache
    maxElementsInMemory="10000"
    eternal="false"
    timeToIdleSeconds="120"
    timeToLiveSeconds="120"
    maxElementsOnDisk="10000000"
    diskExpiryThreadIntervalSeconds="120"
    memoryStoreEvictionPolicy="LRU"/>
   <!-- 配置名为users的缓存区 -->
  <cache name="users"
    maxElementsInMemory="10000"
    eternal="false"
    overflowToDisk="true"
    timeToIdleSeconds="300"
    timeToLiveSeconds="600" />
</ehcache>

package org.crazyit.app.domain;
public class User
{
   private String name;
   private int age;
   public User()
   {}
   public User(String name, int age)
   {
      super();
      this.name = name;
      this.age = age;
   }
   public String getName()
   {
      return name;
   }
   public void setName(String name)
   {
      this.name = name;
   }
   public int getAge()
   {
      return age;
   }
   public void setAge(int age)
   {
      this.age = age;
   }
}

package org.crazyit.app.service;
import org.crazyit.app.domain.User;
public interface UserService
{
   User getUsersByNameAndAge(String name, int age);
   User getAnotherUser(String name, int age);
}

package org.crazyit.app.service.impl;
import org.crazyit.app.service.UserService;
import org.crazyit.app.domain.User;
import org.springframework.stereotype.Service;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.context.annotation.Scope;
@Service("userService")
@Cacheable(value = "users")
public class UserServiceImpl implements UserService
{
  public User getUsersByNameAndAge(String name, int age)
  {
    System.out.println("--正在执行findUsersByNameAndAge()查询方法--");
    return new User(name, age);
  }
  public User getAnotherUser(String name, int age)
  {
    System.out.println("--正在执行findAnotherUser()查询方法--");
    return new User(name, age);
  }
  // 指定根据name、age参数清除缓存
  @CacheEvict(value = "users")
  public void evictUser(String name, int age)
  {
    System.out.println("--正在清空"+ name
      + " , " + age + "对应的缓存--");
  }
  // 指定清除user缓存区所有缓存数据
  @CacheEvict(value = "users" , allEntries=true)
  public void evictAll()
  {
    System.out.println("--正在清空整个缓存--");
  }
}

package lee;
import org.crazyit.app.service.UserService;
import org.crazyit.app.domain.User;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringTest
{
  public static void main(String[] args)
  {
    ApplicationContext ctx =
      new ClassPathXmlApplicationContext("beans.xml");
    UserService us = ctx.getBean("userService" , UserService.class);
    // 调用us对象的2个带缓存的方法，系统会缓存两个方法返回的数据
    User u1 = us.getUsersByNameAndAge("孙悟空", 500);
    User u2 = us.getAnotherUser("猪八戒", 400);
    //调用evictUser()方法清除缓存中指定的数据
    us.evictUser("猪八戒", 400);
    // 由于前面根据"猪八戒", 400缓存的数据已经被清除了，
    // 因此下面代码会重新执行，方法返回的数据将被再次缓存。
    User u3 = us.getAnotherUser("猪八戒", 400); // ①
    System.out.println(u2 == u3); // 输出false
    // 由于前面前面已经缓存了参数为"孙悟空", 500的数据，
    // 因此下面代码不会重新执行，直接利用缓存中的数据。
    User u4 = us.getAnotherUser("孙悟空", 500);  // ②
    System.out.println(u1 == u4); // 输出true
    // 清空整个缓存。
    us.evictAll();
    // 由于整个缓存都已经被清空，因此下面两行代码都会重新执行
    User u5 = us.getAnotherUser("孙悟空", 500);
    User u6 = us.getAnotherUser("猪八戒", 400);
    System.out.println(u1 == u5); // 输出false
    System.out.println(u3 == u6); // 输出false
  }
}