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



    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.6.3
         
    
    com.yl
    cache_redis
    0.0.1-SNAPSHOT
    cache_redis
    Demo project for Spring Boot
    
        11
    
    
        
            org.springframework.boot
            spring-boot-starter-cache
        
            spring-boot-starter-data-redis
            spring-boot-starter-web

            spring-boot-starter-test
            test
    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin

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



    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.6.3
         
    
    com.yl
    ehcache
    0.0.1-SNAPSHOT
    ehcache
    Demo project for Spring Boot
    
        11
    
    
        
            org.springframework.boot
            spring-boot-starter-cache
        
            spring-boot-starter-web

            spring-boot-starter-test
            test
            net.sf.ehcache
            ehcache
            2.10.6
    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin

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