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查询码: 00000480

ehcache入门基础示例 - CSDN博客

作者: 系统管理员于 2018年05月17日 发布在分类 / 技术研发 / 开源组件 ,于 2018年05月17日编辑

缓存 ehcache public 数据 string cachemanager spring version 使用 springframework

一：目录

EhCache 简介
Hello World 示例
Spring 整合

二：简介

1. 基本介绍

EhCache 是一个纯Java的进程内缓存框架，具有快速、精干等特点，是Hibernate中默认CacheProvider。Ehcache是一种广泛使用的开源Java分布式缓存。主要面向通用缓存,Java EE和轻量级容器。它具有内存和磁盘存储，缓存加载器,缓存扩展,缓存异常处理程序,一个gzip缓存servlet过滤器,支持REST和SOAP api等特点。

Spring 提供了对缓存功能的抽象：即允许绑定不同的缓存解决方案（如Ehcache），但本身不直接提供缓存功能的实现。它支持注解方式使用缓存，非常方便。

2. 主要的特性有：

快速
简单
多种缓存策略
缓存数据有两级：内存和磁盘，因此无需担心容量问题
缓存数据会在虚拟机重启的过程中写入磁盘
可以通过RMI、可插入API等方式进行分布式缓存
具有缓存和缓存管理器的侦听接口
支持多缓存管理器实例，以及一个实例的多个缓存区域
提供Hibernate的缓存实现

3. 集成

可以单独使用，一般在第三方库中被用到的比较多（如mybatis、shiro等）ehcache 对分布式支持不够好，多个节点不能同步，通常和redis一块使用

4. ehcache 和 redis 比较

ehcache直接在jvm虚拟机中缓存，速度快，效率高；但是缓存共享麻烦，集群分布式应用不方便。
redis是通过socket访问到缓存服务，效率比ecache低，比数据库要快很多，
处理集群和分布式缓存方便，有成熟的方案。如果是单个应用或者对缓存访问要求很高的应用，用ehcache。如果是大型系统，存在缓存共享、分布式部署、缓存内容很大的，建议用redis。

ehcache也有缓存共享方案，不过是通过RMI或者Jgroup多播方式进行广播缓存通知更新，缓存共享复杂，维护不方便；简单的共享可以，但是涉及到缓存恢复，大数据缓存，则不合适。

三： Hello World

1、在pom.xml中引入依赖

<dependency>
    <groupId>net.sf.ehcache</groupId>
    <artifactId>ehcache</artifactId>
    <version>2.10.2</version>
</dependency>

2、在src/main/resources/创建一个配置文件 ehcache.xml

默认情况下Ehcache会自动加载classpath根目录下名为ehcache.xml文件，也可以将该文件放到其他地方在使用时指定文件的位置

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd">
 
  <!-- 磁盘缓存位置 -->
  <diskStore path="java.io.tmpdir/ehcache"/>
 
  <!-- 默认缓存 -->
  <defaultCache
          maxEntriesLocalHeap="10000"
          eternal="false"
          timeToIdleSeconds="120"
          timeToLiveSeconds="120"
          maxEntriesLocalDisk="10000000"
          diskExpiryThreadIntervalSeconds="120"
          memoryStoreEvictionPolicy="LRU">
    <persistence strategy="localTempSwap"/>
  </defaultCache>
 
  <!-- helloworld缓存 -->
  <cache name="HelloWorldCache"
         maxElementsInMemory="1000"
         eternal="false"
         timeToIdleSeconds="5"
         timeToLiveSeconds="5"
         overflowToDisk="false"
         memoryStoreEvictionPolicy="LRU"/>
</ehcache>

3、测试类

package com.mengdee.manage.cache;
 
import com.mengdee.manage.entity.Dog;
 
import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;
 
public class CacheTest {
 
    public static void main(String[] args) {
 
        // 1. 创建缓存管理器
        CacheManager cacheManager = CacheManager.create("./src/main/resources/ehcache.xml");
 
        // 2. 获取缓存对象
        Cache cache = cacheManager.getCache("HelloWorldCache");
 
        // 3. 创建元素
        Element element = new Element("key1", "value1");
 
        // 4. 将元素添加到缓存
        cache.put(element);
 
        // 5. 获取缓存
        Element value = cache.get("key1");
        System.out.println(value);
        System.out.println(value.getObjectValue());
 
        // 6. 删除元素
        cache.remove("key1");
 
        Dog dog = new Dog(1L, "taidi", (short)2);
        Element element2 = new Element("taidi", dog);
        cache.put(element2);
        Element value2 = cache.get("taidi");
        Dog dog2 = (Dog) value2.getObjectValue();
        System.out.println(dog2);
 
        System.out.println(cache.getSize());
 
        // 7. 刷新缓存
        cache.flush();
 
        // 8. 关闭缓存管理器
        cacheManager.shutdown();
    }
}

4、缓存配置

一：xml配置方式：

diskStore ： ehcache支持内存和磁盘两种存储
- path ：指定磁盘存储的位置
defaultCache ：默认的缓存
- maxEntriesLocalHeap=”10000”
- eternal=”false”
- timeToIdleSeconds=”120”
- timeToLiveSeconds=”120”
- maxEntriesLocalDisk=”10000000”
- diskExpiryThreadIntervalSeconds=”120”
- memoryStoreEvictionPolicy=”LRU”
cache ：自定的缓存，当自定的配置不满足实际情况时可以通过自定义（可以包含多个cache节点）
- name : 缓存的名称，可以通过指定名称获取指定的某个Cache对象
- maxElementsInMemory ：内存中允许存储的最大的元素个数，0代表无限个
- clearOnFlush：内存数量最大时是否清除。
- eternal ：设置缓存中对象是否为永久的，如果是，超时设置将被忽略，对象从不过期。根据存储数据的不同，例如一些静态不变的数据如省市区等可以设置为永不过时
- timeToIdleSeconds ：设置对象在失效前的允许闲置时间（单位：秒）。仅当eternal=false对象不是永久有效时使用，可选属性，默认值是0，也就是可闲置时间无穷大。
- timeToLiveSeconds ：缓存数据的生存时间（TTL），也就是一个元素从构建到消亡的最大时间间隔值，这只能在元素不是永久驻留时有效，如果该值是0就意味着元素可以停顿无穷长的时间。
- overflowToDisk ：内存不足时，是否启用磁盘缓存。
- maxEntriesLocalDisk：当内存中对象数量达到maxElementsInMemory时，Ehcache将会对象写到磁盘中。
- maxElementsOnDisk：硬盘最大缓存个数。
- diskSpoolBufferSizeMB：这个参数设置DiskStore（磁盘缓存）的缓存区大小。默认是30MB。每个Cache都应该有自己的一个缓冲区。
- diskPersistent：是否在VM重启时存储硬盘的缓存数据。默认值是false。
- diskExpiryThreadIntervalSeconds：磁盘失效线程运行时间间隔，默认是120秒。

二：编程方式配置

Cache cache = manager.getCache(<span>"mycache"</span>); 
CacheConfiguration config = cache.getCacheConfiguration(); 
config.setTimeToIdleSeconds(<span>60</span>); 
config.setTimeToLiveSeconds(<span>120</span>); 
config.setmaxEntriesLocalHeap(<span>10000</span>); 
config.setmaxEntriesLocalDisk(<span>1000000</span>);

5、Ehcache API

CacheManager：Cache的容器对象，并管理着（添加或删除）Cache的生命周期。

1	`<span>// 可以自己创建一个Cache对象添加到CacheManager中</span> <span>public</span> <span>void</span> <span>addCache</span>(Cache cache); <span>public</span> <span>synchronized</span> <span>void</span> <span>removeCache</span>(String cacheName);`

Cache: 一个Cache可以包含多个Element，并被CacheManager管理。它实现了对缓存的逻辑行为
Element：需要缓存的元素，它维护着一个键值对，元素也可以设置有效期，0代表无限制
获取CacheManager的方式：

可以通过create()或者newInstance()方法或重载方法来创建获取CacheManager的方式：

<span>public</span> <span>static</span> CacheManager <span>create</span>(); <span>public</span> <span>static</span> CacheManager <span>create</span>(String configurationFileName); <span> public</span> <span>static</span> CacheManager <span>create</span>(InputStream inputStream); <span> public</span> <span>static</span> CacheManager <span>create</span>(URL configurationFileURL); <span>public</span> <span>static</span> CacheManager <span>newInstance</span>();

Ehcache的CacheManager构造函数或工厂方法被调用时，会默认加载classpath下名为ehcache.xml的配置文件。
如果加载失败，会加载Ehcache jar包中的ehcache-failsafe.xml文件，这个文件中含有简单的默认配置。

<span>// CacheManager.create() == CacheManager.create("./src/main/resources/ehcache.xml")</span> <span> // 使用Ehcache默认配置新建一个CacheManager实例</span> CacheManager cacheManager = CacheManager.create();
cacheManager = CacheManager.newInstance();
cacheManager = CacheManager.newInstance(<span>"./src/main/resources/ehcache.xml"</span>);
InputStream inputStream = <span>new</span> FileInputStream(<span>new</span> File(<span>"./src/main/resources/ehcache.xml"</span>));
cacheManager = CacheManager.newInstance(inputStream);
String[] cacheNames = cacheManager.getCacheNames(); <span> // [HelloWorldCache]</span>

四：Spring整合

示例结构：

这里写图片描述

1. pom.xml 引入spring和ehcache

<span><<span>project</span> <span>xmlns</span>=<span>"http://maven.apache.org/POM/4.0.0"</span> <span> xmlns:xsi</span>=<span>"http://www.w3.org/2001/XMLSchema-instance"</span> <span> xsi:schemaLocation</span>=<span>"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"</span>></span> <span><<span>modelVersion</span>></span>4.0.0<span></<span>modelVersion</span>></span> <span><<span>groupId</span>></span>com.mengdee<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>ehcache<span></<span>artifactId</span>></span> <span><<span>version</span>></span>0.0.1-SNAPSHOT<span></<span>version</span>></span> <span> <<span>properties</span>></span> <span> <<span>project.build.sourceEncoding</span>></span>UTF-8<span></<span>project.build.sourceEncoding</span>></span> <span> <<span>junit.version</span>></span>4.10<span></<span>junit.version</span>></span> <span><<span>spring.version</span>></span>4.2.3.RELEASE<span></<span>spring.version</span>></span> <span></<span>properties</span>></span> <span> <<span>dependencies</span>></span> <span><<span>dependency</span>></span> <span><<span>groupId</span>></span>junit<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>junit<span></<span>artifactId</span>></span> <span> <<span>version</span>></span>${junit.version}<span></<span>version</span>></span> <span><<span>scope</span>></span>test<span></<span>scope</span>></span> <span></<span>dependency</span>></span> <span><<span>dependency</span>></span> <span><<span>groupId</span>></span>org.springframework<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>spring-test<span></<span>artifactId</span>></span> <span><<span>version</span>></span>${spring.version}<span></<span>version</span>></span> <span><<span>scope</span>></span>test<span></<span>scope</span>></span> <span></<span>dependency</span>></span> <span><!-- springframework --></span> <span><<span>dependency</span>></span> <span><<span>groupId</span>></span>org.springframework<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>spring-webmvc<span></<span>artifactId</span>></span> <span><<span>version</span>></span>${spring.version}<span></<span>version</span>></span> <span></<span>dependency</span>></span> <span><<span>dependency</span>></span> <span><<span>groupId</span>></span>org.springframework<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>spring-core<span></<span>artifactId</span>></span> <span><<span>version</span>></span>${spring.version}<span></<span>version</span>></span> <span></<span>dependency</span>></span> <span><<span>dependency</span>></span> <span> <<span>groupId</span>></span>org.springframework<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>spring-context<span></<span>artifactId</span>></span> <span><<span>version</span>></span>${spring.version}<span></<span>version</span>></span> <span></<span>dependency</span>></span> <span><<span>dependency</span>></span> <span><<span>groupId</span>></span>org.springframework<span></<span>groupId</span>></span> <span><<span>artifactId</span>></span>spring-context-support<span></<span>artifactId</span>></span> <span><<span>version</span>></span>${spring.version}<span></<span>version</span>></span> <span></<span>dependency</span>></span> <span><<span>dependency</span>></span> <span><<span>groupId</span>></span>net.sf.ehcache<span></<span>groupId</span>> </span> <span><<span>artifactId</span>></span>ehcache<span></<span>artifactId</span>></span> <span><<span>version</span>></span>2.10.3<span></<span>version</span>></span> <span></<span>dependency</span>></span> <span></<span>dependencies</span>></span> <span><<span>repositories</span>></span> <span><<span>repository</span>></span> <span><<span>id</span>></span>aliyun<span></<span>id</span>></span> <span><<span>name</span>></span>aliyun<span></<span>name</span>></span> <span><<span>url</span>></span>http://maven.aliyun.com/nexus/content/groups/public<span></<span>url</span>></span> <span></<span>repository</span>></span> <span></<span>repositories</span>></span> <span></<span>project</span>></span>

2. 在src/main/resources添加ehcache.xml

<span><?xml version="1.0" encoding="UTF-8"?></span> <span><<span>ehcache</span> <span>xmlns:xsi</span>=<span>"http://www.w3.org/2001/XMLSchema-instance"</span> <span>xsi:noNamespaceSchemaLocation</span>=<span>"http://ehcache.org/ehcache.xsd"</span>></span> <span><!-- 磁盘缓存位置 --></span> <span><<span>diskStore</span> <span>path</span>=<span>"java.io.tmpdir/ehcache"</span> /></span> <span><!-- 默认缓存 --></span> <span><<span>defaultCache </span> <span>maxEntriesLocalHeap</span>=<span>"10000"</span> <span>eternal</span>=<span>"false"</span> <span>timeToIdleSeconds</span>=<span>"120"</span> <span>timeToLiveSeconds</span>=<span>"120"</span> <span>maxEntriesLocalDisk</span>=<span>"10000000"</span> <span>diskExpiryThreadIntervalSeconds</span>=<span>"120"</span> <span>memoryStoreEvictionPolicy</span>=<span>"LRU"</span>></span> <span><<span>persistence</span> <span>strategy</span>=<span>"localTempSwap"</span>/></span> <span></<span>defaultCache</span>></span> <span><!-- helloworld缓存 --></span> <span><<span>cache</span> <span>name</span>=<span>"HelloWorldCache"</span> <span>maxElementsInMemory</span>=<span>"1000"</span> <span>eternal</span>=<span>"false"</span> <span>timeToIdleSeconds</span>=<span>"5"</span> <span>timeToLiveSeconds</span>=<span>"5"</span> <span>overflowToDisk</span>=<span>"false"</span> <span>memoryStoreEvictionPolicy</span>=<span>"LRU"</span>/></span> <span><<span>cache</span> <span>name</span>=<span>"UserCache"</span> <span>maxElementsInMemory</span>=<span>"1000"</span> <span>eternal</span>=<span>"false"</span> <span>timeToIdleSeconds</span>=<span>"1800"</span> <span>timeToLiveSeconds</span>=<span>"1800"</span> <span>overflowToDisk</span>=<span>"false"</span> <span>memoryStoreEvictionPolicy</span>=<span>"LRU"</span>/></span> <span></<span>ehcache</span>></span>

3. 在src/main/resources/conf/spring中配置spring-base.xml和spring-ehcache.xml

spring-base.xml

<span><?xml version="1.0" encoding="UTF-8"?></span> <span><<span>beans</span> <span>xmlns</span>=<span>"http://www.springframework.org/schema/beans"</span> <span>xmlns:xsi</span>=<span>"http://www.w3.org/2001/XMLSchema-instance"</span> <span>xmlns:context</span>=<span>"http://www.springframework.org/schema/context"</span> <span>xmlns:util</span>=<span>"http://www.springframework.org/schema/util"</span> <span>xsi:schemaLocation</span>=<span>"http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"</span>></span> <span><<span>context:component-scan</span> <span>base-package</span>=<span>"com.mengdee.**.dao,com.mengdee.**.service"</span>/></span> <span></<span>beans</span>></span>

spring-ehcache.xml

<span><?xml version="1.0" encoding="UTF-8"?></span> <span><<span>beans</span> <span>xmlns</span>=<span>"http://www.springframework.org/schema/beans"</span> <span>xmlns:xsi</span>=<span>"http://www.w3.org/2001/XMLSchema-instance"</span> <span>xmlns:cache</span>=<span>"http://www.springframework.org/schema/cache"</span> <span>xsi:schemaLocation</span>=<span>"http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-3.2.xsd"</span>></span> <span><<span>description</span>></span>ehcache缓存配置管理文件<span></<span>description</span>></span> <span><!-- 启用缓存注解开关 --></span> <span><<span>cache:annotation-driven</span> <span>cache-manager</span>=<span>"cacheManager"</span>/></span> <span><<span>bean</span> <span>id</span>=<span>"cacheManager"</span> <span>class</span>=<span>"org.springframework.cache.ehcache.EhCacheCacheManager"</span>></span> <span><<span>property</span> <span>name</span>=<span>"cacheManager"</span> <span>ref</span>=<span>"ehcache"</span>/></span> <span></<span>bean</span>></span> <span><<span>bean</span> <span>id</span>=<span>"ehcache"</span> <span>class</span>=<span>"org.springframework.cache.ehcache.EhCacheManagerFactoryBean"</span>></span> <span><<span>property</span> <span>name</span>=<span>"configLocation"</span> <span>value</span>=<span>"classpath:ehcache.xml"</span>/></span> <span></<span>bean</span>></span> <span></<span>beans</span>></span>

4、在src/main/java/com.mengdee.manager.service/下创建EhcacheService和EhcacheServiceImpl

EhcacheService

<span>package</span> com.mengdee.manager.service; <span>import</span> com.mengdee.manager.entity.User; <span>public</span> <span><span>interface</span> <span>EhcacheService</span> {</span> <span>// 测试失效情况，有效期为5秒</span> <span>public</span> String <span>getTimestamp</span>(String param); <span>public</span> String <span>getDataFromDB</span>(String key); <span>public</span> <span>void</span> <span>removeDataAtDB</span>(String key); <span>public</span> String <span>refreshData</span>(String key); <span>public</span> User <span>findById</span>(String userId); <span>public</span> <span>boolean</span> <span>isReserved</span>(String userId); <span>public</span> <span>void</span> <span>removeUser</span>(String userId); <span>public</span> <span>void</span> <span>removeAllUser</span>();

}

EhcacheServiceImpl:

<span>package</span> com.mengdee.manager.service; <span>import</span> org.springframework.cache.annotation.CacheEvict; <span>import</span> org.springframework.cache.annotation.CachePut; <span>import</span> org.springframework.cache.annotation.Cacheable; <span>import</span> org.springframework.stereotype.Service; <span>import</span> com.mengdee.manager.entity.User; <span>@Service</span> <span>public</span> <span><span>class</span> <span>EhcacheServiceImpl</span> <span>implements</span> <span>EhcacheService</span>{</span> <span>// value的值和ehcache.xml中的配置保持一致</span> <span>@Cacheable</span>(value=<span>"HelloWorldCache"</span>, key=<span>"#param"</span>) <span>@Override</span> <span>public</span> String <span>getTimestamp</span>(String param) {
    Long timestamp = System.currentTimeMillis(); <span>return</span> timestamp.toString();
  } <span>@Cacheable</span>(value=<span>"HelloWorldCache"</span>, key=<span>"#key"</span>) <span>@Override</span> <span>public</span> String <span>getDataFromDB</span>(String key) {
    System.out.println(<span>"从数据库中获取数据..."</span>); <span>return</span> key + <span>":"</span> + String.valueOf(Math.round(Math.random()*<span>1000000</span>));
  } <span>@CacheEvict</span>(value=<span>"HelloWorldCache"</span>, key=<span>"#key"</span>) <span>@Override</span> <span>public</span> <span>void</span> <span>removeDataAtDB</span>(String key) {
    System.out.println(<span>"从数据库中删除数据"</span>);
  } <span>@CachePut</span>(value=<span>"HelloWorldCache"</span>, key=<span>"#key"</span>) <span>@Override</span> <span>public</span> String <span>refreshData</span>(String key) {
    System.out.println(<span>"模拟从数据库中加载数据"</span>); <span>return</span> key + <span>"::"</span> + String.valueOf(Math.round(Math.random()*<span>1000000</span>));
  } <span>// ------------------------------------------------------------------------</span> <span>@Cacheable</span>(value=<span>"UserCache"</span>, key=<span>"'user:' + #userId"</span>) <span>public</span> User <span>findById</span>(String userId) { 
    System.out.println(<span>"模拟从数据库中查询数据"</span>); <span>return</span> (User) <span>new</span> User(<span>"1"</span>, <span>"mengdee"</span>);      
  } <span>@Cacheable</span>(value=<span>"UserCache"</span>, condition=<span>"#userId.length()<12"</span>) <span>public</span> <span>boolean</span> <span>isReserved</span>(String userId) {  
    System.out.println(<span>"UserCache:"</span>+userId); <span>return</span> <span>false</span>;  
  } <span>//清除掉UserCache中某个指定key的缓存 </span> <span>@CacheEvict</span>(value=<span>"UserCache"</span>,key=<span>"'user:' + #userId"</span>) <span>public</span> <span>void</span> <span>removeUser</span>(String userId) {  
    System.out.println(<span>"UserCache remove:"</span>+ userId);  
  } <span>//清除掉UserCache中全部的缓存 </span> <span>@CacheEvict</span>(value=<span>"UserCache"</span>, allEntries=<span>true</span>) <span>public</span> <span>void</span> <span>removeAllUser</span>() {  
    System.out.println(<span>"UserCache delete all"</span>);  
  }
}

注解基本使用方法

Spring对缓存的支持类似于对事务的支持。
首先使用注解标记方法，相当于定义了切点，然后使用Aop技术在这个方法的调用前、调用后获取方法的入参和返回值，进而实现了缓存的逻辑。

@Cacheable

表明所修饰的方法是可以缓存的：当第一次调用这个方法时，它的结果会被缓存下来，在缓存的有效时间内，以后访问这个方法都直接返回缓存结果，不再执行方法中的代码段。
这个注解可以用condition属性来设置条件，如果不满足条件，就不使用缓存能力，直接执行方法。
可以使用key属性来指定key的生成规则。

@Cacheable 支持如下几个参数：

value：缓存位置名称，不能为空，如果使用EHCache，就是ehcache.xml中声明的cache的name, 指明将值缓存到哪个Cache中
key：缓存的key，默认为空，既表示使用方法的参数类型及参数值作为key，支持SpEL，如果要引用参数值使用井号加参数名，如：#userId，

一般来说，我们的更新操作只需要刷新缓存中某一个值，所以定义缓存的key值的方式就很重要，最好是能够唯一，因为这样可以准确的清除掉特定的缓存，而不会影响到其它缓存值，
本例子中使用实体加冒号再加ID组合成键的名称，如”user:1”、”order:223123”等
condition：触发条件，只有满足条件的情况才会加入缓存，默认为空，既表示全部都加入缓存，支持SpEL

<span>// 将缓存保存到名称为UserCache中，键为"user:"字符串加上userId值，如 'user:1'</span> <span>@Cacheable</span>(value=<span>"UserCache"</span>, key=<span>"'user:' + #userId"</span>) <span>public</span> User <span>findById</span>(String userId) { <span>return</span> (User) <span>new</span> User(<span>"1"</span>, <span>"mengdee"</span>);      
} <span>// 将缓存保存进UserCache中，并当参数userId的长度小于12时才保存进缓存，默认使用参数值及类型作为缓存的key</span> <span>// 保存缓存需要指定key，value， value的数据类型，不指定key默认和参数名一样如："1"</span> <span>@Cacheable</span>(value=<span>"UserCache"</span>, condition=<span>"#userId.length() < 12"</span>) <span>public</span> <span>boolean</span> <span>isReserved</span>(String userId) {  
  System.out.println(<span>"UserCache:"</span>+userId); <span>return</span> <span>false</span>;  
}

@CachePut

与@Cacheable不同，@CachePut不仅会缓存方法的结果，还会执行方法的代码段。它支持的属性和用法都与@Cacheable一致。
@CacheEvict

与@Cacheable功能相反，@CacheEvict表明所修饰的方法是用来删除失效或无用的缓存数据。

@CacheEvict 支持如下几个参数：
- value：缓存位置名称，不能为空，同上
- key：缓存的key，默认为空，同上
- condition：触发条件，只有满足条件的情况才会清除缓存，默认为空，支持SpEL
- allEntries：true表示清除value中的全部缓存，默认为false

<span>//清除掉UserCache中某个指定key的缓存 </span> <span>@CacheEvict</span>(value=<span>"UserCache"</span>,key=<span>"'user:' + #userId"</span>) <span>public</span> <span>void</span> <span>removeUser</span>(User user) {  
  System.out.println(<span>"UserCache"</span>+user.getUserId());  
} <span>//清除掉UserCache中全部的缓存 </span> <span>@CacheEvict</span>(value=<span>"UserCache"</span>, allEntries=<span>true</span>) <span>public</span> <span>final</span> <span>void</span> <span>setReservedUsers</span>(String[] reservedUsers) {  
  System.out.println(<span>"UserCache deleteall"</span>);  
}

5、测试

SpringTestCase

<span>package</span> com.mengdee.manager; <span>import</span> org.junit.runner.RunWith; <span>import</span> org.springframework.test.context.ContextConfiguration; <span>import</span> org.springframework.test.context.junit4.AbstractJUnit4SpringContextTests; <span>import</span> org.springframework.test.context.junit4.SpringJUnit4ClassRunner; <span>@ContextConfiguration</span>(locations = {<span>"classpath:conf/spring/spring-*.xml"</span>}) <span>@RunWith</span>(SpringJUnit4ClassRunner.class) <span>public</span> <span><span>class</span> <span>SpringTestCase</span> <span>extends</span> <span>AbstractJUnit4SpringContextTests</span>{</span> }

<span>package</span> com.mengdee.manager; <span>import</span> org.junit.Test; <span>import</span> org.springframework.beans.factory.annotation.Autowired; <span>import</span> com.mengdee.manager.service.EhcacheService; <span>public</span> <span><span>class</span> <span>EhcacheServiceTest</span> <span>extends</span> <span>SpringTestCase</span>{</span> <span>@Autowired</span> <span>private</span> EhcacheService ehcacheService; <span>// 有效时间是5秒，第一次和第二次获取的值是一样的，因第三次是5秒之后所以会获取新的值</span> <span>@Test</span> <span>public</span> <span>void</span> <span>testTimestamp</span>() <span>throws</span> InterruptedException{
    System.out.println(<span>"第一次调用："</span> + ehcacheService.getTimestamp(<span>"param"</span>));
    Thread.sleep(<span>2000</span>);
    System.out.println(<span>"2秒之后调用："</span> + ehcacheService.getTimestamp(<span>"param"</span>));
    Thread.sleep(<span>4000</span>);
    System.out.println(<span>"再过4秒之后调用："</span> + ehcacheService.getTimestamp(<span>"param"</span>));
  } <span>@Test</span> <span>public</span> <span>void</span> <span>testCache</span>(){
    String key = <span>"zhangsan"</span>;
    String value = ehcacheService.getDataFromDB(key); <span>// 从数据库中获取数据...</span> ehcacheService.getDataFromDB(key); <span>// 从缓存中获取数据，所以不执行该方法体</span> ehcacheService.removeDataAtDB(key); <span>// 从数据库中删除数据</span> ehcacheService.getDataFromDB(key); <span>// 从数据库中获取数据...（缓存数据删除了，所以要重新获取，执行方法体）</span> } <span>@Test</span> <span>public</span> <span>void</span> <span>testPut</span>(){
    String key = <span>"mengdee"</span>;
    ehcacheService.refreshData(key); <span>// 模拟从数据库中加载数据</span> String data = ehcacheService.getDataFromDB(key);
    System.out.println(<span>"data:"</span> + data); <span>// data:mengdee::103385</span> ehcacheService.refreshData(key); <span>// 模拟从数据库中加载数据</span> String data2 = ehcacheService.getDataFromDB(key);
    System.out.println(<span>"data2:"</span> + data2); <span>// data2:mengdee::180538 </span> } <span>@Test</span> <span>public</span> <span>void</span> <span>testFindById</span>(){
    ehcacheService.findById(<span>"1"</span>); <span>// 模拟从数据库中查询数据</span> ehcacheService.findById(<span>"1"</span>);
  } <span>@Test</span> <span>public</span> <span>void</span> <span>testIsReserved</span>(){
    ehcacheService.isReserved(<span>"123"</span>);
    ehcacheService.isReserved(<span>"123"</span>);
  } <span>@Test</span> <span>public</span> <span>void</span> <span>testRemoveUser</span>(){ <span>// 线添加到缓存</span> ehcacheService.findById(<span>"1"</span>); <span>// 再删除</span> ehcacheService.removeUser(<span>"1"</span>); <span>// 如果不存在会执行方法体</span> ehcacheService.findById(<span>"1"</span>);
  } <span>@Test</span> <span>public</span> <span>void</span> <span>testRemoveAllUser</span>(){
    ehcacheService.findById(<span>"1"</span>);
    ehcacheService.findById(<span>"2"</span>);
 
    ehcacheService.removeAllUser();
 
    ehcacheService.findById(<span>"1"</span>);
    ehcacheService.findById(<span>"2"</span>); <span>// 模拟从数据库中查询数据</span> <span>// 模拟从数据库中查询数据</span> <span>// UserCache delete all</span> <span>// 模拟从数据库中查询数据</span> <span>// 模拟从数据库中查询数据</span> }
 
}