Spring实战——缓存使用condition

阳光穿透心脏的1/2处 2021-07-24 18:54 389阅读 0赞

**一 配置文件**

<?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" />
         
         <bean id="ehCacheManager"
               class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"
               p:configLocation="classpath:ehcache.xml"  p:shared="false" />
         
         <bean id="cacheManager"
               class="org.springframework.cache.ehcache.EhCacheCacheManager"
               p:cacheManager-ref="ehCacheManager">
         </bean>
    </beans>

**二 属性文件**

<?xml version="1.0" encoding="gbk"?>
    <ehcache>
        <diskStore path="java.io.tmpdir" />
         
        <defaultCache
            maxElementsInMemory="10000"
            eternal="false"
            timeToIdleSeconds="120"
            timeToLiveSeconds="120"
            maxElementsOnDisk="10000000"
            diskExpiryThreadIntervalSeconds="120"
            memoryStoreEvictionPolicy="LRU"/>
         
        <cache name="users"
            maxElementsInMemory="10000"
            eternal="false"
            overflowToDisk="true"
            timeToIdleSeconds="300"
            timeToLiveSeconds="600" />
    </ehcache>

**三 领域模型**

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;
         }
         
         
    }

**四 Service**

1 接口类

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);
    }

2 实现类

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.context.annotation.Scope;
    
    
    @Service("userService")
    @Cacheable(value = "users" , condition="#age<100")
    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);
        }
    }

**五 测试类**

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);
            // 调用方法时age参数不小于100，因此不会缓存，
            // 所以下面两次方法调用都会真正执行这些方法。
            User u1 = us.getUsersByNameAndAge("孙悟空", 500);
            User u2 = us.getAnotherUser("孙悟空", 500);
            System.out.println(u1 == u2); // 输出false
            // 调用方法时age参数小于100，因此会缓存，
            // 所以下面第二次方法调用时不会真正执行该方法，而是直接使用缓存数据。
            User u3 = us.getUsersByNameAndAge("孙悟空", 50);
            User u4 = us.getAnotherUser("孙悟空", 50);
            System.out.println(u3 == u4); // 输出true
        }
    }

**六 测试结果**

--正在执行findUsersByNameAndAge()查询方法--
    --正在执行findAnotherUser()查询方法--
    false
    --正在执行findUsersByNameAndAge()查询方法--
    true