Spring Cloud分布式Session共享实践

通常情况下，Tomcat、Jetty等Servlet容器，会默认将Session保存在内存中。如果是单个服务器实例的应用，将Session保存在服务器内存中是一个非常好的方案。但是这种方案有一个缺点，就是不利于扩展。

目前越来越多的应用采用分布式部署，用于实现高可用性和负载均衡等。那么问题来了，如果将同一个应用部署在多个服务器上通过负载均衡对外提供访问，如何实现Session共享？

实际上实现Session共享的方案很多，其中一种常用的就是使用Tomcat、Jetty等服务器提供的Session共享功能，将Session的内容统一存储在一个数据库（如MySQL）或缓存（如Redis）中。

下面我们将在springcloud微服务项目中，使用redis实现简单高效的session共享。

项目介绍

• eureka-server：注册中心
• springcloud-session-redis：业务session所在项目
• springcloud-session-zuul：路由网关

eureka-server延用之前Eureka服务注册与发现一文中的注册中心，不再赘述

springcloud-session-redis项目

新建一个spring boot项目，命名springcloud-session-redis

POM依赖配置

 <?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

     <groupId>com.carry</groupId>
     <artifactId>springcloud-session-redis</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>

     <name>springcloud-session-redis</name>
     <description>Demo project for Spring Boot</description>

     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>2.0.4.RELEASE</version>
         <relativePath /> <!-- lookup parent from repository -->
     </parent>

     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <java.version>1.8</java.version>
         <spring-cloud.version>Finchley.SR1</spring-cloud.version>
     </properties>

     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-redis</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.session</groupId>
             <artifactId>spring-session-data-redis</artifactId>
         </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-pool2</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-actuator</artifactId>
         </dependency>

     </dependencies>

     <dependencyManagement>
         <dependencies>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-dependencies</artifactId>
                 <version>${spring-cloud.version}</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
         </dependencies>
     </dependencyManagement>

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

 </project>

配置文件

在application.yml中加入redis、eureka、port等配置

server:
  port: 8090
spring:
  application:
    name: service-session-redis
  redis:
    host: 192.168.68.100
    port: 6379
    password: 123456
    timeout: 6000ms
    lettuce:
      pool:
        max-active: 8
        max-wait: -1ms
        max-idle: 8
        min-idle: 0
    database: 0
eureka:
  client:
    serviceUrl:
      defaultZone: http://admin:123456@localhost:8761/eureka/
management:
  endpoints:
    web:
      exposure:
        include: "*"
      cors:
        allowed-origins: "*"
        allowed-methods: "*" 

Redis Session配置类

 package com.carry.config;

 import org.springframework.context.annotation.Configuration;
 import org.springframework.session.data.redis.config.annotation.web.http.EnableRedisHttpSession;

 @Configuration
 @EnableRedisHttpSession
 public class RedisSessionConfig {

 }

控制层Controller中添加测试方法

 package com.carry.controller;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpSession;

 import org.springframework.cloud.context.config.annotation.RefreshScope;
 import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;

 @RestController
 @RefreshScope
 public class UserManagementController {

     /**
      * redis sesion共享
      *
      * @param request
      * @return
      */
     @GetMapping("/getUser")
     public String getUser(HttpServletRequest request) {
         HttpSession session = request.getSession();
         String username = (String) session.getAttribute("username");
         if (StringUtils.isEmpty(username)) {
             username = "testSessionRedis|" + System.currentTimeMillis();
             session.setAttribute("username", username);
         }
         System.out.println("访问端口：" + request.getServerPort());
         return username;
     }
 }

springcloud-session-zuul项目

新建springboot项目，命名springcloud-session-zuul

POM依赖配置

 <?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

     <groupId>com.carry</groupId>
     <artifactId>springcloud-session-zuul</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>

     <name>springcloud-session-zuul</name>
     <description>Demo project for Spring Boot</description>

     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>2.0.4.RELEASE</version>
         <relativePath /> <!-- lookup parent from repository -->
     </parent>

     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <java.version>1.8</java.version>
         <spring-cloud.version>Finchley.SR1</spring-cloud.version>
     </properties>

     <dependencies>
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
         </dependency>
     </dependencies>

     <dependencyManagement>
         <dependencies>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-dependencies</artifactId>
                 <version>${spring-cloud.version}</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
         </dependencies>
     </dependencyManagement>

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

 </project>

配置文件

server:
  port: 1100
spring:
  application:
    name: service-session-zuul
zuul:
  ignoredServices: '*' #忽略所有未配置的service
  host:
    connect-timeout-millis: 20000
    socket-timeout-millis: 20000
  routes:
    redis-session-service:
      path: /user-session/**
      serviceId: service-session-redis
      sensitiveHeaders: "*"
ribbon: #ribbon负载均衡参数配置
  ReadTimeout: 5000
  ConnectTimeout: 5000
eureka:
  client:
    serviceUrl:
      defaultZone: http://admin:123456@localhost:8761/eureka/

启动类

 package com.carry;

 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
 import org.springframework.cloud.netflix.zuul.EnableZuulProxy;

 @EnableEurekaClient
 @SpringBootApplication
 @EnableZuulProxy
 public class SpringcloudSessionZuulApplication {

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

测试

依次启动

• eureka-server
• springcloud-session-redis
• springcloud-session-zuul

多次访问网关地址http://localhost:1100/user-session/getUser，发现后台轮询访问springcloud-session-redis的8090与8091两个实例

而我们页面得到的结果是不变的，由此可以说明session是一致的

注意：springcloud项目中经过网关zuul转发请求后发生session失效问题，这是由于zuul默认会丢弃原来的session并生成新的session，解决方法网关配置文件application.yml 中添加 sensitiveHeaders: “*”