spring boot2 缓存推荐 springboot常用缓存技术

引子

我门知道一个程序的瓶颈在于数据库，我门也知道内存的速度是大大快于硬盘的速度的。当我门需要重复的获取相同的数据的时候，我门一次又一次的请求数据库或者远程服务，导致大量的时间耗费在数据库查询或者远程方法的调用上，导致程序性能的恶化，这更是数据缓存要解决的问题。

spring 缓存支持

spring定义了 org.springframework.cache.CacheManager和org.springframework.cache.Cache接口来统一不同的缓存技术。其中，CacheManager是Spring提供的各种缓存技术抽象接口，Cache接口包含了缓存的各种操作（增加、删除获得缓存，我门一般不会直接和此接口打交道）

spring 支持的CacheManager

针对不同的缓存技术，需要实现不同的CacheManager ,spring 定义了如下表的CacheManager实现。

实现任意一种CacheManager 的时候，需要注册实现CacheManager的bean，当然每种缓存技术都有很多额外的配置，但配置CacheManager 是必不可少的。

声明式缓存注解

spring提供了4个注解来声明缓存规则（又是使用注解式的AOP的一个生动例子），如表。

开启声明式缓存

开启声明式缓存支持非常简单，只需要在配置类上使用@EnabelCaching 注解即可。

springBoot 的支持

在spring中国年使用缓存技术的关键是配置CacheManager 而springbok 为我门自动配置了多个CacheManager的实现。在spring boot 环境下，使用缓存技术只需要在项目中导入相关缓存技术的依赖包，并配置类使用@EnabelCaching开启缓存支持即可。

---

小例子

小例子是使用 springboot+jpa ＋cache 实现的。

实例步骤目录

• 1.创建maven项目
• 2.数据库配置
• 3.jpa配置和cache配置
• 4.编写bean 和dao层
• 5.编写service层
• 6.编写controller
• 7.启动cache
• 8.测试校验

---

1.创建maven项目

新建maven 项目pom.xml文件如下内容如下：

<?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>

    <groupId>com.us</groupId>
    <artifactId>springboot-Cache</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.0.RELEASE</version>
    </parent>

    <properties>
        <start-class>com.us.Application</start-class>

        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
    </properties>

    <!-- Add typical dependencies for a web application -->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

        <!--db-->

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.5</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

    </dependencies>

</project>

2.数据库配置

在src/main/esouces目录下新建application.properties 文件，内容为数据库连接信息，如下：
application.properties

ms.db.driverClassName=com.mysql.jdbc.Driver
ms.db.url=jdbc:mysql://localhost:3306/cache?prepStmtCacheSize=517&cachePrepStmts=true&autoReconnect=true&useUnicode=true&characterEncoding=utf-8&useSSL=false&allowMultiQueries=true
ms.db.username=root
ms.db.password=xxxxxx
ms.db.maxActive=500

新建DBConfig.java 配置文件，配置数据源

package com.us.example.config;

/**
 * Created by yangyibo on 17/1/13.
 */
import java.beans.PropertyVetoException;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import com.mchange.v2.c3p0.ComboPooledDataSource;

@Configuration
public class DBConfig {
    @Autowired
    private Environment env;

    @Bean(name="dataSource")
    public ComboPooledDataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass(env.getProperty("ms.db.driverClassName"));
        dataSource.setJdbcUrl(env.getProperty("ms.db.url"));
        dataSource.setUser(env.getProperty("ms.db.username"));
        dataSource.setPassword(env.getProperty("ms.db.password"));
        dataSource.setMaxPoolSize(20);
        dataSource.setMinPoolSize(5);
        dataSource.setInitialPoolSize(10);
        dataSource.setMaxIdleTime(300);
        dataSource.setAcquireIncrement(5);
        dataSource.setIdleConnectionTestPeriod(60);

        return dataSource;
    }
}

数据库设计，数据库只有一张Person表，设计如下：

3.jpa配置

spring－data－ jpa 配置文件如下：

package com.us.example.config;

import java.util.HashMap;
import java.util.Map;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

/**
 * Created by yangyibo on 17/1/13.
 */

@Configuration
@EnableJpaRepositories("com.us.example.dao")
@EnableTransactionManagement
@ComponentScan
public class JpaConfig {
    @Autowired
    private DataSource dataSource;

    @Bean
    public EntityManagerFactory entityManagerFactory() {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setPackagesToScan("com.us.example.bean");
        factory.setDataSource(dataSource);


        Map<String, Object> jpaProperties = new HashMap<>();
        jpaProperties.put("hibernate.ejb.naming_strategy","org.hibernate.cfg.ImprovedNamingStrategy");
        jpaProperties.put("hibernate.jdbc.batch_size",50);
        factory.setJpaPropertyMap(jpaProperties);
        factory.afterPropertiesSet();
        return factory.getObject();
    }

    @Bean
    public PlatformTransactionManager transactionManager() {

        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory());
        return txManager;
    }
}

4.编写bean 和dao层

实体类 Person.java

package com.us.example.bean;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

/**
 * Created by yangyibo on 17/1/13.
 */
@Entity
@Table(name = "Person")
public class Person {
    @Id
    @GeneratedValue
    private Long id;

    private String name;

    private Integer age;

    private String address;

    public Person() {
        super();
    }
    public Person(Long id, String name, Integer age, String address) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
        this.address = address;
    }
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }


}

dao层，PersonRepository.java

package com.us.example.dao;

import com.us.example.bean.Person;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * Created by yangyibo on 17/1/13.
 */
public interface PersonRepository extends JpaRepository<Person, Long> {

}

5.编写service层

service 接口

package com.us.example.service;

import com.us.example.bean.Person;

/**
 * Created by yangyibo on 17/1/13.
 */
public  interface DemoService {
    public Person save(Person person);

    public void remove(Long id);

    public Person findOne(Person person);

}

实现：(重点，此处加缓存)

package com.us.example.service.Impl;

import com.us.example.bean.Person;
import com.us.example.dao.PersonRepository;
import com.us.example.service.DemoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

/**
 * Created by yangyibo on 17/1/13.
 */
@Service
public class DemoServiceImpl implements DemoService {

    @Autowired
    private PersonRepository personRepository;

    @Override
    //@CachePut缓存新增的或更新的数据到缓存,其中缓存名字是 people 。数据的key是person的id
    @CachePut(value = "people", key = "#person.id")
    public Person save(Person person) {
        Person p = personRepository.save(person);
        System.out.println("为id、key为:"+p.getId()+"数据做了缓存");
        return p;
    }

    @Override
    //@CacheEvict 从缓存people中删除key为id 的数据
    @CacheEvict(value = "people")
    public void remove(Long id) {
        System.out.println("删除了id、key为"+id+"的数据缓存");
        //这里不做实际删除操作
    }

    @Override
    //@Cacheable缓存key为person 的id 数据到缓存people 中,如果没有指定key则方法参数作为key保存到缓存中。
    @Cacheable(value = "people", key = "#person.id")
    public Person findOne(Person person) {
        Person p = personRepository.findOne(person.getId());
        System.out.println("为id、key为:"+p.getId()+"数据做了缓存");
        return p;
    }

}

6.编写controller

为了测试方便请求方式都用了get

package com.us.example.controller;
import com.us.example.bean.Person;
import com.us.example.service.DemoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by yangyibo on 17/1/13.
 */
@RestController
public class CacheController {

    @Autowired
   private DemoService demoService;

    //http://localhost:8080/put?name=abel&age=23&address=shanghai
    @RequestMapping("/put")
    public Person put(Person person){
        return demoService.save(person);

    }

    //http://localhost:8080/able?id=1
    @RequestMapping("/able")
    @ResponseBody
    public Person cacheable(Person person){


        return demoService.findOne(person);

    }

    //http://localhost:8080/evit?id=1
    @RequestMapping("/evit")
    public String  evit(Long id){
        demoService.remove(id);
        return "ok";

    }


}

7.启动cache

启动类中要记得开启缓存配置。

package com.us.example;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;

import static org.springframework.boot.SpringApplication.*;

/**
 * Created by yangyibo on 17/1/13.
 */

@ComponentScan(basePackages ="com.us.example")
@SpringBootApplication
@EnableCaching
public class Application {
    public static void main(String[] args) {
        ConfigurableApplicationContext run = run(Application.class, args);
    }

}

8.测试校验

检验able：

启动Application 类，启动后在浏览器输入：http://localhost:8080/able?id=1（首先要在数据库中初始化几条数据。）

控制台输出：
“为id、key为:1数据做了缓存“ 此时已经为此次查询做了缓存，再次查询该条数据将不会出现此条语句，也就是不查询数据库了。

检验put

在浏览器输入：http://localhost:8080/put?name=abel&age=23&address=shanghai（向数据库插入一条数据，并将数据放入缓存。）

此时控制台输出为该条记录做了缓存：

然后再次调用able 方法，查询该条数据，将不再查询数据库，直接从缓存中读取数据。

测试evit

在浏览器输入：http://localhost:8080/evit?id=1（将该条记录从缓存中清楚，清除后，在次访问该条记录，将会重新将该记录放入缓存。）

控制台输出：

切换缓存

1.切换为EhCache作为缓存

pom.xml 文件中添加依赖

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

在resource 文件夹下新建ehcache的配置文件ehcache.xml 内容如下，此文件spring boot 会自动扫描

<?xml version="1.0" encoding="UTF-8"?>
<ehcache>
    <!--切换为ehcache 缓存时使用-->
<cache name="people" maxElementsInMemory="1000" />
</ehcache>

2.切换为Guava作为缓存

只需要在pom中添加依赖

<dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>18.0</version>
        </dependency>