SpringBoot集成Redis / 四六文摘

根据学生 id 查询学生的功能，先从 redis 缓存中查找，如果找不到，再从数据库中查找，然后放到 redis 缓存中

一、通过 MyBatis 逆向工程生成实体 bean 和数据持久层

具体过程看之前写的

二、在 pom.xml 文件中添加 redis 依赖

完整的pom文件

<?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>2.3.4.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.md</groupId><artifactId>04-redis</artifactId><version>1.0.0</version><name>04-redis</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--redis依赖--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.0.0</version></dependency><!--mysql依赖--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.9</version></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><!--加载mapper.xml文件--><resources><resource><directory>src/main/java</directory><includes><include>**/*.xml</include></includes></resource></resources><plugins><!--mybatis 代码自动生成插件--><plugin><groupId>org.mybatis.generator</groupId><artifactId>mybatis-generator-maven-plugin</artifactId><version>1.3.6</version><configuration><!--配置文件的位置--><configurationFile>GeneratorMapper.xml</configurationFile><verbose>true</verbose><overwrite>true</overwrite></configuration></plugin></plugins></build></project>

三、Spring Boot 核心配置文件

根据自己的情况进行修改

#配置内嵌 Tomcat 端口号server.port=9090#配置项目上下文根server.servlet.context-path=/#用的mysql5.7spring.datasource.driver-class-name=com.mysql.jdbc.Driverspring.datasource.url=jdbc:mysql://localhost:3306/springbootspring.datasource.username=rootspring.datasource.password=123456#配置 redis 连接信息spring.redis.host=192.168.52.130spring.redis.port=6379spring.redis.password=123456

四、启动 redis 服务

先关闭防火墙：systemctl stop firewalld
根据如下命令启动即可
还得先设置密码，在redis的配置文件redis.conf中有个参数，requirepass 这个就是配置redis访问密码的参数，例：requirepass 123456，然后重启就生效了

五、RedisController类

package com.md.web;import com.md.service.StudentService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RestController;/** * @author md * @Desc * @date 2020/10/24 15:50 */@RestControllerpublic class RedisController {    @Autowired    private StudentService studentService;    @GetMapping(value = "/students")    public Object allStudentCount(){        Long i = studentService.queryAllStudentCount();        return "学生的总人数为："+i;    }}

六、StudentService 接口及实现

Spring Boot 将自动配置 RedisTemplate，在需要操作 redis 的类中注入 redisTemplate 即可

Spring Boot 帮我们注入 RedisTemplate 类，泛型里面只能写 <String, String>、<Object, Object> 或者什么都不写

重点看注释

package com.md.service;/** * @author md * @Desc * @date 2020/10/24 15:53 */public interface StudentService {    Long queryAllStudentCount();}package com.md.service.impl;import com.md.mapper.StudentMapper;import com.md.service.StudentService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.data.redis.serializer.StringRedisSerializer;import org.springframework.stereotype.Service;import java.util.concurrent.TimeUnit;/** * @author md * @Desc * @date 2020/10/24 15:57 */@Servicepublic class StudentServiceImpl implements StudentService {    @Autowired    private StudentMapper studentMapper;    @Autowired    private RedisTemplate<Object, Object> redisTemplate;    @Override    public Long queryAllStudentCount() {        // 设置redisTemplate对象key的序列化方式        redisTemplate.setKeySerializer(new StringRedisSerializer());        // 从redis缓存中获取总人数        Long allStudentCount = (Long) redisTemplate.opsForValue().get("allStudentCount");        // 判断redis中是否存在数据        if(null == allStudentCount){            // 如果为空，就去数据库中进行查询            allStudentCount = studentMapper.selectAllStudentCount();            // 并且把查询到的数据放入大redis中            redisTemplate.opsForValue().set("allStudentCount",allStudentCount,15, TimeUnit.SECONDS);        }        return allStudentCount;    }}

七、StudentMapper接口及映射文件

直接在自动生成的文件中添加自定义的功能就可以了

Long selectAllStudentCount();mapper文件中 <select id="selectAllStudentCount" resultType="java.lang.Long">    select      count(*)    from      t_student  </select>

八、启动类 Application

添加扫描数据持久层的注解并指定扫描包

package com.md;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication@MapperScan(basePackages = "com.md.mapper")public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}}