SpringBoot中使用数据缓存

在实际开发中，对于要反复读写的数据，最好的处理方式是将之在内存中缓存一份，频繁的数据库访问会造成程序效率低下，同时内存的读写速度本身就要强于硬盘。Spring在这一方面给我们提供了诸多的处理手段，而Spring Boot又将这些处理方式进一步简化，接下来我们就来看看如何在Spring Boot中解决数据缓存问题。

标题

使用MySQL，在pom.xml中添加数据库驱动。
pom.xml

<?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.wangh</groupId>
    <artifactId>springboot_cache</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot_cache</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <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-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

配置application.properties

spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/girl?useUnicode=true&characterEncoding=utf-8
spring.datasource.username=system
spring.datasource.password=mysql

spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jackson.serialization.indent_output=true

创建实体类

@Entity
public class Person {
    @Id
    @GeneratedValue
    private Long id;
    private String name;
    private String address;
    private Integer age;

    public Person() {
    }

    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 String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Person(Long id, String name, String address, Integer age) {
        this.id = id;
        this.name = name;
        this.address = address;
        this.age = age;
    }
}

创建实体类的Repository

public interface PersonRepository extends JpaRepository<Person,Long> {
}

创建业务类

业务接口

public interface PersonService {

    Person save(Person person);
    void remove(Long id);
    Person findOne(Person person);
}

实现类

@Service
public class PersonServiceImpl implements PersonService {

    @Resource
    private PersonRepository personRepository;


    //@CachePut： 新增或更新数据到缓存，缓存名称为people，数据的key是person.id
    @CachePut(value = "people", key = "#person.id") 
    @Override
    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;
    }

    //@CacheEvict:从缓存people中删除key为id的数据，如果没有指定key,方法参数作为key保存在缓存中
    @CacheEvict(value = "people")
    @Override
    public void remove(Long id) {
        System.out.println("删除了key为" + id + "数据缓存");
        personRepository.delete(id);
    }

    //key为person的id数据缓存到people中
    @Cacheable(value = "people", key = "#person.id")
    @Override
    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;
    }

}

关于这个实现类注意如下几点：

1.@CachePut表示缓存新添加的数据或者更新的数据到缓存中，两个参数value表示缓存的名称为people，key表示缓存的key为person的id
2.@CacheEvict表示从缓存people中删除key为id的数据
3.@Cacheable表示添加数据到缓存中，缓存名称为people，缓存key为person的id属性。

创建Controller

@RestController
public class CacheController {

    @Resource
    private PersonService personService;

    @RequestMapping("/put")
    public Person put(Person person){
        return personService.save(person);
    }

    @RequestMapping("/cache")
    public Person cache(Person person){
        return personService.findOne(person);
    }

    @RequestMapping("/evict")
    public String evict(Long id){
        personService.remove(id);
        return "ok";
    }
}

大功告成了！