Spring/SpringBoot系列之SpringBoot集成Ehcache，只需三步【十八】

1. 添加依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<dependency>
    <groupId>org.ehcache</groupId>
    <artifactId>ehcache</artifactId>
</dependency>
<dependency>
    <groupId>javax.cache</groupId>
    <artifactId>cache-api</artifactId>
</dependency>

依赖说明：

• spring-boot-starter-cache：Spring Boot提供的缓存支持；
• 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

2.1 准备工作

2.1.1 创建Person实体类

package com.linyf.demo.ehcache;

import lombok.*;

import java.io.Serializable;

@Data
@AllArgsConstructor
public class Person implements Serializable {

    private Long id;

    private String username;

    private String email;
}

说明：@Data和@AllArgsConstructor为lombok中的注解，不了解的推荐阅读：效率工具Lombok

2.1.2 定义缓存事件监听器

用于记录系统操作缓存数据的情况，实现CacheEventListener接口：

package com.linyf.demo.ehcache;

import org.ehcache.event.CacheEvent;
import org.ehcache.event.CacheEventListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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());
    }
}

2.2 创建缓存配置文件ehcache.xml

在resources资源根目录下创建ehcache.xml，内容如下：

<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.Longkey-type>
        <value-type>com.linyf.demo.ehcache.Personvalue-type>
        <expiry>
            <ttl unit="minutes">1ttl>
        expiry>
        <listeners>
            <listener>
                <class>com.linyf.demo.ehcache.PersonCacheEventLoggerclass>
                <event-firing-mode>ASYNCHRONOUSevent-firing-mode>
                <event-ordering-mode>UNORDEREDevent-ordering-mode>
                <events-to-fire-on>CREATEDevents-to-fire-on>
                <events-to-fire-on>UPDATEDevents-to-fire-on>
                <events-to-fire-on>EXPIREDevents-to-fire-on>
                <events-to-fire-on>REMOVEDevents-to-fire-on>
                <events-to-fire-on>EVICTEDevents-to-fire-on>
            listener>
        listeners>
        <resources>
            <heap unit="entries">2000heap>
            <offheap unit="MB">100offheap>
        resources>
    cache>
config>

2.3 指定ehcache.xml路径

现在需要告诉Spring Boot去哪里找缓存配置文件，在application.yml中进行设置：

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

2.4 开启缓存功能

使用@EnableCaching注解开启Spring Boot应用程序缓存功能，可以添加到启动类中：

package com.linyf.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;


@SpringBootApplication
@EnableCaching
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

3. 使用@Cacheable

package com.linyf.demo.ehcache;

import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

@Service(value = "personService")
public class PersonService {

    @Cacheable(cacheNames = "person", key = "#id")
    public Person getPerson(Long id){
        Person person = new Person(id,"linyf","[email protected]");
        return person;
    }
}

4. 测试

创建controller：

package com.linyf.demo.ehcache;

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;

@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);
    }
}

然后通过浏览器访问：

看控制台打印信息，打印了一条创建缓存数据的日志：

因为是第一次访问，缓存中没有，所以会创建一个缓存数据存到缓存中，有效时间是一分钟。

一分钟内再次访问，就会读取缓存，所以不会打印任何日志，隔一分钟后再次访问，打印了两条日志，一条过期日志，一条创建日志：