1、远程服务器端要关闭防火墙

 systemctl stop firewalld.service

或者关闭后设置 禁止防火墙开机启动。

 systemctl disable firewalld.service  

2.关闭 redis 保护模式，在 redis.conf 文件中

 [root@localhost redis-7.0.7]# vi redis.conf 

修改 protected 为 no，如下：

image.png

注释掉 redis 的 ip 地址绑定，还是在 redis.conf 中，将 bind:127.0.0.1 注释掉，如下：

image.png

确认了这三步之后，就可以远程连接 redis 了

pom.xml

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
    </parent>
    <dependencies> 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--热部署配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
            <scope>runtime</scope>
        </dependency>
        <!-- redis相关 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId> 
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
    </dependencies>
</project>

application.yml

 server:
    port: 8089
    servlet:
        context-path: /elm
spring:
    datasource:
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://localhost:3306/emp?characterEncoding=utf-8&useSSL=false
        username: root
        password: root
    redis:
        database: 0
        host: 远程ip地址
        port: 6379
logging:
    level:
        org.springframework: debug
        com.xx.dao: debug 
        #能看到控制台sql语句日志，方便区分是从缓存中读数据还是访问mapper都mysql数据
mybatis:
   # mapper-locations: classpath:mapper/*.xml
    type-aliases-package: com.xx.boot.po

主启动类上加@EnableCaching注解启用缓存

@SpringBootApplication
@EnableCaching
public class HelloApplication {
    public static void main(String[] args) {
        SpringApplication.run(HelloApplication.class, args);
    }
}

实体类 需要实现 Serializable 序列化

public class Dept  implements Serializable{ 
    private Integer deptno;
    private String dname;
    private String loc;
    //getter,setter省略
}

mapper层接口

@Mapper
public interface DeptMapper {
    @Select("select * from dept")
    public List<Dept> getDept();

    @Select("select * from dept where deptno = #{deptno}")
    public Dept getDeptById(Integer deptno);

    @Delete("delete from dept where deptno = #{deptno}")
    public Integer delDeptById(Integer deptno);
}

service层接口

public interface DeptService {
    public List<Dept> getDept();
       
    public  Dept  getDeptById(Integer deptno);
     
    public Integer delDeptById(Integer deptno);
}

service层实现类

 @Service
public class DeptServiceImpl implements DeptService {

    @Autowired
    DeptMapper deptMapper;

    @Autowired
    RedisTemplate<Object, Object> redisTemplate;
    
    public List<Dept> getDept() { 
        List<Dept> list = null; 
        ValueOperations<Object, Object> op = redisTemplate.opsForValue();
        if(op.get("user")==null) { 
            list = deptMapper.getDept( );
            op.set("user",  list);
        }else {
            list = (List<Dept>) op.get("user");
            System.out.println(list);
        } 
        return list; 
    }

    @Cacheable(value = "dept",key = "#deptno",unless = "#result==null")
    public Dept getDeptById(Integer deptno) { 
        //可通过控制台日志查看是否有sql输出，有就证明读mysql了，没有就证明从缓存中读的
        Dept dept = deptMapper.getDeptById(deptno); 
        return dept;
    }


    @CacheEvict(value = "dept",key = "#deptno")
    public Integer delDeptById(Integer deptno) { 
        return deptMapper.delDeptById(deptno);
    }
 
}

@Cacheable解的作用是将 value = "dept",key = "#deptno" 值作为组合，作为缓存数据的键值 , #的参数是将方法参数deptno取出的意思，每次访问该方法时，注解会到缓存中检查是否有value 和 key 值作为组合的键值存在，若存在，则不会调用该方法，也就不会执行mapper的方法，否则就会调用方法，并把返回值存入缓存作为value,key值则是 value = "user",key = "#id"的组合
unless是缓存条件，上例中是结果不为空时进行缓存

@CacheEvict 注解是删除功能，当访问该方法时，若存在value = "user",key = "#id" 组合而成的键值，就把该缓存数据删除

controller层

@RestController
public class HelloController {
    @Autowired
    DeptService deptService;
    
    @RequestMapping("/getDept")
    public List<Dept> getDept(){           
        return deptService.getDept();
    }
     
    @RequestMapping("/getDeptById")
    public Dept getDeptById(Integer deptno) { 
        return deptService.getDeptById(deptno);
    }
     
    @RequestMapping("/delDeptById")
    public Integer delDeptById(Integer deptno) { 
        return deptService.delDeptById(deptno);
    }
}