SpringBoot与SpringCache概念用法大全

1.SpringCache的概念

首先我们知道jpa,jdbc这些东西都是一些规范，比如jdbc，要要连接到数据库，都是需要用到数据库连接，预处理，结果集这三个对象，无论是连接到mysql还是oracle都是需要用到这个三个对象的，这是一种规范，而SpringCache是一种作为缓存的规范，具体实现有redis,EhCahe等

2.SpringCache用法（redis版）

2.1 .SpringCache基本用法

1.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 https://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>2.6.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yl</groupId>
    <artifactId>cache_redis</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>cache_redis</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>
            <artifactId>spring-boot-starter-data-redis</artifactId>
            <artifactId>spring-boot-starter-web</artifactId>

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

2.application.properties

# redis的配置
spring.redis.host=192.168.244.135
spring.redis.port=6379
spring.redis.password=root123

3.实体类

package com.yl.cache_redis.domain;
import java.io.Serializable;
public class User implements Serializable {
    private Integer id;
    private String username;
    private String password;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

4.service

package com.yl.cache_redis;

import com.yl.cache_redis.domain.User;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
@Service
public class UserService {
    @Cacheable(cacheNames = "u1") //这个注解作用就是将方法的返回值存到缓存中
    public User getUserById(Integer id) {
        System.out.println("getUserById:" + id);
        User user = new User();
        user.setId(id);
        user.setUsername("root");
        user.setPassword("root");
        return user;
    }
}

5.主程序，加上开启缓存的注解

package com.yl.cache_redis;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
@SpringBootApplication
@EnableCaching //开启缓存功能
public class CacheRedisApplication {
    public static void main(String[] args) {
        SpringApplication.run(CacheRedisApplication.class, args);
    }
}

6.测试

6.1）userservice没加@Cacheable注解时

6.2）userservice加@Cacheable注解后，发现sevice中的方法只调用了一次

6.3）在redis中也可以看到缓存中有数据，key为定义好的cacheNames+::+方法的参数

2.2 .SpringCache自定义缓存key

1.SpringCache默认使用cacheNames和方法中的参数结合组成key的，那么如果有多个参数呢？它又是如何组成key的呢？我们可以指定key吗？

2.如何自定义key呢？

1）自定义key

package com.yl.cache_redis;

import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.stereotype.Component;
import java.lang.reflect.Method;
import java.util.Arrays;
@Component
public class MyKeyGenerator implements KeyGenerator {
    @Override
    public Object generate(Object target, Method method, Object... params) {
        return target.toString() + ":" + method.getName() + ":" + Arrays.toString(params);
    }
}

2）测试

2.3 .SpringCache更新缓存

1.使用@CachePut注解来更新，注意：@CachePut中的key要和@Cacheable中的key一样，否则更新不了！

2.4 .SpringCache清空缓存

1.使用@CacheEvict注解，主要key和要@Cacheable中的key一致

2.测试

2.5 .SpringCache其他用法

1.@Caching注解，可以组合多个注解

2.@CacheConfig注解

3.SpringCache用法（EhCache版）

1.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 https://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>2.6.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yl</groupId>
    <artifactId>ehcache</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>ehcache</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>
            <artifactId>spring-boot-starter-web</artifactId>

            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <groupId>net.sf.ehcache</groupId>
            <artifactId>ehcache</artifactId>
            <version>2.10.6</version>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.实体类

package com.yl.ehcache.model;
import java.io.Serializable;
public class User implements Serializable {
    private Integer id;
    private String username;
    private String password;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

3.service

package com.yl.ehcache.service;

import com.yl.ehcache.model.User;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
@Service
public class UserService {
    @Cacheable(cacheNames = "user")
    public User getUserById(Integer id) {
        System.out.println("getUserById()...");
        User user = new User();
        user.setId(id);
        user.setUsername("root");
        user.setPassword("root");
        return user;
    }
    @CacheEvict(cacheNames = "user")
    public void delete(Integer id) {
        System.out.println("delete");
}

4.主程序

package com.yl.ehcache;

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

5.ehcache.xml

<ehcache>
    <diskStore path="java.io.tmpdir/shiro-spring-sample"/>
    <defaultCache
            maxElementsInMemory = "1000"
            eternal = "false"
            timeToIdleSeconds = "120"
            timeToLiveSeconds = "120"
            overflowToDisk = "false"
            diskPersistent = "false"
            diskExpiryThreadIntervalSeconds = "120"/>
    <cache name = "user"
           maxElementsInMemory = "1000"
           eternal = "false"
           overflowToDisk = "true"
           diskPersistent = "true"
           diskExpiryThreadIntervalSeconds = "600"/>
</ehcache>