https://docs.spring.io/spring-session/docs/current/reference/html5/guides/boot-redis.html

1.添加依赖
<dependencies>

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-redis</artifactId>
</dependency>

</dependencies>

2.开启Spring Session Redis
src/main/resources/application.properties中添加
spring.session.store-type=redis # Session store type.

3.配置redis链接
spring.redis.host=localhost # Redis server host.
spring.redis.password= # Login password of the redis server.
spring.redis.port=6379 # Redis server port.

4.启动springboot和redis就可以使用啦
只要使用了session：request.getSession().setAttribute("username", "admin");
就可以在redis中找到记录