SpringBoot+Redis+Nginx实现负载均衡以及Session缓存共享

1.环境信息

nginx-1.11.10

redis-latest包（redis windows版本）

springboot1.5.1.RELEASE

2.新建一个SpringBoot项目，参考如下链接：https://segmentfault.com/a/11...

3.nginx和redis解压缩即可，并正常启动





4.springboot集成Redis以及springboot，需要在POM文件中增加依赖

<?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.example</groupId>
<artifactId>demo3</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>demo</name>
<description>Demo project for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.1.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>
</properties>

<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.3.5.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.session</groupId>
<artifactId>spring-session-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-redis</artifactId>
<version>1.3.8.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-redis</artifactId>
</dependency>
</dependencies>

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

5.新建Controller类DemoController.java

@Controller
public class DemoController {
@Autowired
DemoService demoService;

@RequestMapping("testcache")
@ResponseBody
public String testCache(@RequestParam String key){
String s = demoService.testCache(key);
return s;
}

@RequestMapping("/getseansession")
@ResponseBody
public Map<String,String> getSession(HttpServletRequest request){
Map<String,String> attributeMap = new HashMap<String, String>();
request.getSession().setAttribute("message", request.getRequestURI());
attributeMap.put("message", request.getRequestURI());
System.out.println("sessionID:" + request.getSession().getId());
return attributeMap;
}
}

6.新建Service类DemoService.java

@Service
public class DemoService {
@Cacheable(value = "keycache")
public String testCache(String key){
System.out.println("testCache:" + key);
return key;
}
}

7.新建RedisConfig类增加@EnableRedisHttpSession注解

@Configuration
@EnableCaching
@EnableRedisHttpSession
public class RedisConfig{
}

8.application.properties文件配置，其中为了测试ngnix负载均衡功能，本工程配置为8080端口，另一个springboot工程可以配置为别的端口，比如8088，以便启动两个Server

#redis spring.redis.password=xxx
#spring.redis.database= # database name
spring.redis.hostname=127.0.0.1 # server host
spring.redis.port=6379
spring.redis.pool.maxActive=8
spring.redis.pool.maxWait=-1
spring.redis.pool.maxIdle=8
spring.redis.pool.minIdle=0
spring.redis.timeout=0

#tomcat port configuration
server.port=8080

可以看到启动了两个Server，DemoApplication和DemoApplication(1)



9.ngnix.conf配置文件中配置负载均衡策略

upstream test {
server localhost:8080;
server localhost:8088;
}

server {
listen       80;
server_name  localhost;
client_max_body_size 1024M;

#charset koi8-r;

#access_log  logs/host.access.log  main;

#location / {
#    root   html;
#    index  index.html index.htm;
#}

location / {
proxy_pass http://test/getseansession; proxy_set_header Host $host:$server_port;
}

10.访问http://localhost，会发现http请求交替访问后端两个server。且sessionID是一样的“sessionID:ad0cbb3b-d24d-4d61-87ac-b9ddcfeccaa4”。并没有因为server不一致而sessionID不同





使用RedisClient连接Redis Server，确实存储了一个sessionID，如下：



11.maven工程目录



12.实际操纵过程中遇到一个问题：启动springboot工程的时候报错“java.lang.IllegalStateException: Cannot load configuration class: org.springframework.boot.autoconfigure.cache.RedisCacheConfiguration”



解决方法：对于spring-context-support依赖，增加了一个version，且版本为4.3.5.RELEASE。启动，未报错，问题解决。没配version的时候，默认是4.3.6.RELEASE，奇怪。后续有时间再研究。

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.3.5.RELEASE</version>
</dependency>