Spring Boot 集成 Ehcache 缓存，三步搞定！

时间 2019-12-30

标签 spring boot 集成 ehcache 缓存三步搞定栏目 Spring 繁體版

原文原文链接

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，咱们能够经过Spring Caching来快速搞定数据缓存。java

接下来咱们将介绍如何在三步以内搞定 Spring Boot 缓存。web

1. 建立一个Spring Boot工程

你所建立的Spring Boot应用程序的maven依赖文件至少应该是下面的样子：spring

<?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：apache

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

如今，须要告诉Spring Boot去哪里找缓存配置文件，这须要在Spring Boot配置文件中进行设置：api

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

而后使用@EnableCaching注解开启Spring Boot应用程序缓存功能，你能够在应用主类中进行操做：浏览器

package com.ramostear.cache;

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

@SpringBootApplication
@EnableCaching
public class CacheApplication {

    public static void main(String[] args) {
        SpringApplication.run(CacheApplication.class, args);
    }
}

接下来，须要建立一个 ehcache 的配置文件，该文件放置在类路径下，如resources目录下：缓存

<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，还须要定义个缓存事件监听器，用于记录系统操做缓存数据的状况，最快的方法是实现CacheEventListener接口：app

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可以缓存咱们的数据，还须要使用@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须要加入到缓存中：maven

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;
    }
}

经过以上三个步骤，咱们就完成了Spring Boot的缓存功能。接下来，咱们将测试一下缓存的实际状况。ide

4. 缓存测试

为了测试咱们的应用程序，建立一个简单的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
@NoArgsConstructor
public class Person implements Serializable{

    private Long id;

    private String username;

    private String email;
}

以上准备工做都完成后，让咱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以下的信息：

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

此时在观察控制台输出的日志信息：

1. 2019-04-07 01:08:01.001  INFO 6704 --- [nio-8080-exec-1] 
o.s.web.servlet.DispatcherServlet        : Completed 
initialization in 5 ms
2. 2019-04-07 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

因为咱们是第一次请求API，没有任何缓存数据。所以，Ehcache建立了一条缓存数据，能够经过CREATED看一了解到。

咱们在ehcache.xml文件中将缓存过时时间设置成了1分钟（1），所以在一分钟以内咱们刷新浏览器，不会看到有新的日志输出，一分钟以后，缓存过时，咱们再次刷新浏览器，将看到以下的日志输出：
1. 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 null
2. 2019-04-07 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
第一条日志提示缓存已通过期，第二条日志提示Ehcache从新建立了一条缓存数据。

结束语

在本次案例中，经过简单的三个步骤，讲解了基于 Ehcache 的 Spring Boot 应用程序缓存实现。