Spring Boot 集成 Ehcache 缓存，三步搞定！

Java技术栈

发布于 2019-09-08 16:19:21

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发布于 2019-09-08 16:19:21

文章被收录于专栏：Java技术栈 Java技术栈Java技术栈

本次内容主要介绍基于Ehcache 3.0来快速实现Spring Boot应用程序的数据缓存功能。在Spring Boot应用程序中，我们可以通过Spring Caching来快速搞定数据缓存。

接下来我们将介绍如何在三步之内搞定 Spring Boot 缓存。

1. 创建一个Spring Boot工程

你所创建的Spring Boot应用程序的maven依赖文件至少应该是下面的样子：

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>    <parent>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-parent</artifactId>        <version>2.1.3.RELEASE</version>        <relativePath/> <!-- lookup parent from repository -->    </parent>    <groupId>com.ramostear</groupId>    <artifactId>cache</artifactId>    <version>0.0.1-SNAPSHOT</version>    <name>cache</name>    <description>Demo project for Spring Boot</description>
    <properties>        <java.version>1.8</java.version>    </properties>
    <dependencies>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-cache</artifactId>        </dependency>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-web</artifactId>        </dependency>        <dependency>            <groupId>org.ehcache</groupId>            <artifactId>ehcache</artifactId>        </dependency>        <dependency>            <groupId>javax.cache</groupId>            <artifactId>cache-api</artifactId>        </dependency>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-test</artifactId>            <scope>test</scope>        </dependency>        <dependency>            <groupId>org.projectlombok</groupId>            <artifactId>lombok</artifactId>        </dependency>    </dependencies>
    <build>        <plugins>            <plugin>                <groupId>org.springframework.boot</groupId>                <artifactId>spring-boot-maven-plugin</artifactId>            </plugin>        </plugins>    </build>
</project>

依赖说明：

spring-boot-starter-cache为Spring Boot应用程序提供缓存支持
ehcache提供了Ehcache的缓存实现
cache-api 提供了基于JSR-107的缓存规范

2. 配置Ehcache缓存

现在，需要告诉Spring Boot去哪里找缓存配置文件，这需要在Spring Boot配置文件中进行设置：

spring.cache.jcache.config=classpath:ehcache.xml

然后使用@EnableCaching注解开启Spring Boot应用程序缓存功能，你可以在应用主类中进行操作：

package com.ramostear.cache;
import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cache.annotation.EnableCaching;
@SpringBootApplication@EnableCachingpublic class CacheApplication {
    public static void main(String[] args) {        SpringApplication.run(CacheApplication.class, args);    }}

接下来，需要创建一个 ehcache 的配置文件，该文件放置在类路径下，如resources目录下：

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"        xmlns="http://www.ehcache.org/v3"        xmlns:jsr107="http://www.ehcache.org/v3/jsr107"        xsi:schemaLocation="            http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.0.xsd            http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">    <service>        <jsr107:defaults enable-statistics="true"/>    </service>
    <cache alias="person">        <key-type>java.lang.Long</key-type>        <value-type>com.ramostear.cache.entity.Person</value-type>        <expiry>            <ttl unit="minutes">1</ttl>        </expiry>        <listeners>            <listener>                <class>com.ramostear.cache.config.PersonCacheEventLogger</class>                <event-firing-mode>ASYNCHRONOUS</event-firing-mode>                <event-ordering-mode>UNORDERED</event-ordering-mode>                <events-to-fire-on>CREATED</events-to-fire-on>                <events-to-fire-on>UPDATED</events-to-fire-on>                <events-to-fire-on>EXPIRED</events-to-fire-on>                <events-to-fire-on>REMOVED</events-to-fire-on>                <events-to-fire-on>EVICTED</events-to-fire-on>            </listener>        </listeners>        <resources>                <heap unit="entries">2000</heap>                <offheap unit="MB">100</offheap>        </resources>    </cache></config>

最后，还需要定义个缓存事件监听器，用于记录系统操作缓存数据的情况，最快的方法是实现CacheEventListener接口：

package com.ramostear.cache.config;
import org.ehcache.event.CacheEvent;import org.ehcache.event.CacheEventListener;import org.slf4j.Logger;import org.slf4j.LoggerFactory;
/** * @author ramostear * @create-time 2019/4/7 0007-0:48 * @modify by : * @since: */public class PersonCacheEventLogger implements CacheEventListener<Object,Object>{
    private static final Logger logger = LoggerFactory.getLogger(PersonCacheEventLogger.class);
    @Override    public void onEvent(CacheEvent cacheEvent) {        logger.info("person caching event {} {} {} {}",                cacheEvent.getType(),                cacheEvent.getKey(),                cacheEvent.getOldValue(),                cacheEvent.getNewValue());    }}

3. 使用@Cacheable注解

要让Spring Boot能够缓存我们的数据，还需要使用@Cacheable注解对业务方法进行注释，告诉Spring Boot该方法中产生的数据需要加入到缓存中：

package com.ramostear.cache.service;
import com.ramostear.cache.entity.Person;import org.springframework.cache.annotation.Cacheable;import org.springframework.stereotype.Service;
/** * @author ramostear * @create-time 2019/4/7 0007-0:51 * @modify by : * @since: */@Service(value = "personService")public class PersonService {
    @Cacheable(cacheNames = "person",key = "#id")    public Person getPerson(Long id){        Person person = new Person(id,"ramostear","ramostear@163.com");        return person;    }}

通过以上三个步骤，我们就完成了Spring Boot的缓存功能。接下来，我们将测试一下缓存的实际情况。

4. 缓存测试

为了测试我们的应用程序，创建一个简单的Restful端点，它将调用PersonService返回一个Person对象：

package com.ramostear.cache.controller;
import com.ramostear.cache.entity.Person;import com.ramostear.cache.service.PersonService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;

/** * @author ramostear * @create-time 2019/4/7 0007-0:54 * @modify by : * @since: */@RestController@RequestMapping("/persons")public class PersonController {
    @Autowired    private PersonService personService;
    @GetMapping("/{id}")    public ResponseEntity<Person> person(@PathVariable(value = "id") Long id){        return new ResponseEntity<>(personService.getPerson(id), HttpStatus.OK);    }}

Person是一个简单的POJO类：

package com.ramostear.cache.entity;

import lombok.AllArgsConstructor;import lombok.Getter;import lombok.NoArgsConstructor;import lombok.Setter;
import java.io.Serializable;
/** * @author ramostear * @create-time 2019/4/7 0007-0:45 * @modify by : * @since: */@Getter@Setter@AllArgsConstructor@NoArgsConstructorpublic class Person implements Serializable{
    private Long id;
    private String username;
    private String email;}

以上准备工作都完成后，让我们编译并运行应用程序。项目成功启动后，使用浏览器打开：http://localhost:8080/persons/1 ,你将在浏览器页面中看到如下的信息：

{"id":1,"username":"ramostear","email":"ramostear@163.com"}

此时在观察控制台输出的日志信息：

2019-04-07 01:08:01.001  INFO 6704 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 5 ms2019-04-07 01:08:01.054  INFO 6704 --- [e [_default_]-0] c.r.cache.config.PersonCacheEventLogger  : person caching event CREATED 1 null com.ramostear.cache.entity.Person@ba8a729

由于我们是第一次请求API，没有任何缓存数据。因此，Ehcache创建了一条缓存数据，可以通过CREATED看一了解到。 我们在ehcache.xml文件中将缓存过期时间设置成了1分钟（1），因此在一分钟之内我们刷新浏览器，不会看到有新的日志输出，一分钟之后，缓存过期，我们再次刷新浏览器，将看到如下的日志输出：

2019-04-07 01:09:28.612  INFO 6704 --- [e [_default_]-1] c.r.cache.config.PersonCacheEventLogger  : person caching event EXPIRED 1 com.ramostear.cache.entity.Person@a9f3c57 null2019-04-07 01:09:28.612  INFO 6704 --- [e [_default_]-1] c.r.cache.config.PersonCacheEventLogger  : person caching event CREATED 1 null com.ramostear.cache.entity.Person@416900ce