手把手带你入门spring boot整合redis缓存

一、为什么要缓存

1、原因

用缓存，主要有两个用途：高性能、高并发。

• 高性能
  非实时变化的数据-查询mysql耗时需要300ms,存到缓存redis，每次查询仅仅1ms,性能瞬间提升百倍。
• 高并发
  mysql 单机支撑到2K QPS就容易报警了，如果系统中高峰时期1s请求1万，仅单机mysql是支撑不了的，但是使用缓存的话，单机支撑的并发量轻松1s几万~十几万。
  原因是缓存位于内存，内存对高并发的良好支持。

2、问题

常见的缓存问题：

1、缓存与数据库双写不一致
2、缓存雪崩、缓存穿透
3、缓存并发竞争

二、Spring boot的缓存机制

1、SpringCache概述

• SpringCache本身是一个缓存体系的抽象实现，并没有具体的缓存能力，要使用SpringCache还需要配合具体的缓存实现来完成。
• 虽然如此，但是SpringCache是所有Spring支持的缓存结构的基础，而且所有的缓存的使用最后都要归结于SpringCache，那么一来，要想使用SpringCache，还是要仔细研究一下的。

2、缓存注解

SpringCache缓存功能的实现是依靠下面的这几个注解完成的。

@EnableCaching：开启缓存功能
@Cacheable：定义缓存，用于触发缓存
@CachePut：定义更新缓存，触发缓存更新
@CacheEvict：定义清除缓存，触发缓存清除
@Caching：组合定义多种缓存功能
@CacheConfig：定义公共设置，位于class之上

三、spring boot整合mysql+redis缓存项目

1、准备数据源

mysql表：

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for account
-- ----------------------------
DROP TABLE IF EXISTS `account`;
CREATE TABLE `account`  (
  `ID` int(11) NOT NULL COMMENT '编号',
  `UID` int(11) NULL DEFAULT NULL COMMENT '用户编号',
  `MONEY` double NULL DEFAULT NULL COMMENT '金额',
  PRIMARY KEY (`ID`) USING BTREE,
  INDEX `FK_Reference_8`(`UID`) USING BTREE,
  CONSTRAINT `FK_Reference_8` FOREIGN KEY (`UID`) REFERENCES `user` (`id`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of account
-- ----------------------------
INSERT INTO `account` VALUES (1, 46, 1000);
INSERT INTO `account` VALUES (2, 45, 1000);
INSERT INTO `account` VALUES (3, 46, 2000);

-- ----------------------------
-- Table structure for role
-- ----------------------------
DROP TABLE IF EXISTS `role`;
CREATE TABLE `role`  (
  `ID` int(11) NOT NULL COMMENT '编号',
  `ROLE_NAME` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '角色名称',
  `ROLE_DESC` varchar(60) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '角色描述',
  PRIMARY KEY (`ID`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of role
-- ----------------------------
INSERT INTO `role` VALUES (1, '院长', '管理整个学院');
INSERT INTO `role` VALUES (2, '总裁', '管理整个公司');
INSERT INTO `role` VALUES (3, '校长', '管理整个学校');

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户名称',
  `birthday` datetime(0) NULL DEFAULT NULL COMMENT '生日',
  `sex` char(1) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '性别',
  `address` varchar(256) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '地址',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 73 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (41, '老王', '2018-02-27 17:47:08', '男', '北京');
INSERT INTO `user` VALUES (42, '小二王', '2018-03-02 15:09:37', '女', '北京金燕龙');
INSERT INTO `user` VALUES (43, '小二王', '2018-03-04 11:34:34', '女', '北京金燕龙');
INSERT INTO `user` VALUES (45, '传智播客', '2018-03-04 12:04:06', '男', '北京金燕龙');
INSERT INTO `user` VALUES (46, '老王', '2018-03-07 17:37:26', '男', '北京');
INSERT INTO `user` VALUES (48, '小马宝莉', '2018-03-08 11:44:00', '女', '北京修正');
INSERT INTO `user` VALUES (53, '司理理', '2020-04-14 00:22:25', '女', '北齐');


-- ----------------------------
-- Table structure for user_role
-- ----------------------------
DROP TABLE IF EXISTS `user_role`;
CREATE TABLE `user_role`  (
  `UID` int(11) NOT NULL COMMENT '用户编号',
  `RID` int(11) NOT NULL COMMENT '角色编号',
  PRIMARY KEY (`UID`, `RID`) USING BTREE,
  INDEX `FK_Reference_10`(`RID`) USING BTREE,
  CONSTRAINT `FK_Reference_10` FOREIGN KEY (`RID`) REFERENCES `role` (`ID`) ON DELETE RESTRICT ON UPDATE RESTRICT,
  CONSTRAINT `FK_Reference_9` FOREIGN KEY (`UID`) REFERENCES `user` (`id`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of user_role
-- ----------------------------
INSERT INTO `user_role` VALUES (41, 1);
INSERT INTO `user_role` VALUES (45, 1);
INSERT INTO `user_role` VALUES (41, 2);

SET FOREIGN_KEY_CHECKS = 1;

properties.xml配置

spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.url=jdbc:mysql://地址/2020offer?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC

#缓存配置
spring.cache.cache-names=cacheUser

spring.redis.database=0
spring.redis.host=
spring.redis.port=6379
#spring.redis.password=
spring.redis.timeout=20000ms

pom.xml配置

<?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>2.2.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.jp</groupId>
    <artifactId>redis-cache</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>redis-cache</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <!--        mybatis连接配置-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.9</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

<!--        缓存-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>

            <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>

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

</project>

2、数据库查询并缓存

用户类

package com.jp.rediscache.bean;

import java.io.Serializable;
import java.time.Period;

/**
 * @program: redis-cache
 * @description: 用户类
 * @author: CoderPengJiang
 * @create: 2020-04-27 17:11
 **/
public class User implements Serializable {
    private Integer id;
    private String username;
    private String sex;
    private String address;
    private String birthday;

    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 getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

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

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                ", birthday='" + birthday + '\'' +
                '}';
    }
}

用户持久层UserMapper

package com.jp.rediscache.mapper;

import com.jp.rediscache.bean.User;

public interface UserMapper {
    User getUserById(Integer id);
}

用户持久层配置UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.jp.rediscache.mapper.UserMapper">
    <select id="getUserById" resultType="com.jp.rediscache.bean.User">
        select * from user where user.id=#{id}
    </select>
</mapper>

用户业务层并且开启缓存配置

package com.jp.rediscache.service;

import com.jp.rediscache.bean.User;
import com.jp.rediscache.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * @program: redis-cache
 * @description: 用户业务层
 * @author: CoderPengJiang
 * @create: 2020-04-27 17:27
 **/
@Service
@CacheConfig(cacheNames = "cacheUser")
public class UserService {
    @Autowired
    UserMapper userMapper;

   @Cacheable
    public User getUserById(Integer id){
        System.out.println("从数据库中查询数据-------");
        return userMapper.getUserById(id);
    }

    //删除缓存中的数据
    @CacheEvict
    public void deleteUserById(Integer id) {
        System.out.println("deleteUserById>>>" + id);
    }

   @Cacheable
    public User getUserId(Integer id){
        System.out.println("从数据库中查询数据-------");
        User user=new User();
        user.setId(id);
        return user;
    }

    //更新缓存中的数据
    @CachePut(key = "#user.id")
    public User updateUserById(User user) {
        return user;
    }
}

开启缓存

package com.jp.rediscache;

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

@SpringBootApplication
@MapperScan(basePackages = "com.jp.rediscache.mapper")
//开启缓存
@EnableCaching
public class RedisCacheApplication {

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

}

开启测试

package com.jp.rediscache;

import com.jp.rediscache.bean.User;
import com.jp.rediscache.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class RedisCacheApplicationTests {
    @Autowired
    UserService userService;

    @Test
    void contextLoads() {
    }

    @Test

    public void getUserById(){
        User user = userService.getUserById(46);
        userService.deleteUserById(46);
        User user1 = userService.getUserById(46);
        System.out.println(user);
    }

    @Test
    public void getUser(){
        User user1 = userService.getUserId(1);
        System.out.println(user1);
    }


    @Test
    public void updateUser(){
        User user1=userService.getUserById(46);
        User user2=new User();
        user2.setId(46);
        user2.setAddress("湖南");
        user2.setBirthday("2020-04-27");
        user2.setSex("男");
        user2.setUsername("**");
        userService.updateUserById(user2);
        User user3=userService.getUserById(46);
        System.out.println(user1);
        System.out.println(user3);
    }
}

四、结论

springboot整合redis的缓存核心思路就是当开发者调用一个方法时，将方法的参数和返回值作为key/value缓存起来，当再次调用该方法时，如果缓存中有数据，就直接从中获取，否则再去执行该方法。