关于session共享的方式有多种:
(1)通过nginx的ip_hash，根据ip将请求分配到对应的服务器
(2)基于关系型数据库存储
(3)基于cookie存储
(4)服务器内置的session复制域
(5)基于nosql（memcache、redis都可以）
常用的就是1和5，下面研究第5种方式，基于nosql存储session。
其实实现原理也比较简单，在所有的请求之前配置一过滤器，在请求之前操作session，其实spring-session中真正起作用的session过滤器是:SessionRepositoryFilter。spring-session集成了redis与mongodb。
1.添加maven依赖
<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>cn.qlq</groupId> <artifactId>sessionDemo</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <dependency> <groupId>org.springframework.session</groupId> <artifactId>spring-session-data-redis</artifactId> <version>1.2.1.RELEASE</version> </dependency> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.8.1</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>4.2.5</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jsp-api</artifactId> <version>2.0</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.7</source> <target>1.7</target> <encoding>UTF-8</encoding> </configuration> </plugin> <!-- tomcat7插件 --> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <port>88</port> <path>/sess</path> <uriEncoding>UTF-8</uriEncoding> <server>tomcat7</server> </configuration> </plugin> </plugins> </build></project>
2.web.xml添加过滤器
<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name>sessionDemo</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <!--Spring配置 --> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:springMVC.xml</param-value> </context-param> <!-- Spring监听器 --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <filter> <filter-name>springSessionRepositoryFilter</filter-name> <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> </filter> <filter-mapping> <filter-name>springSessionRepositoryFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping></web-app>
3.springMVC.xml配置bean
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd "> <!--1.扫描controller注解(只是扫描@Controller) --> <context:component-scan base-package="cn" /> <bean id="redisHttpSessionConfiguration" class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration"> <property name="maxInactiveIntervalInSeconds" value="600" /> </bean> <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig"> <property name="maxTotal" value="100" /> <property name="maxIdle" value="10" /> </bean> <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory" destroy-method="destroy"> <property name="hostName" value="127.0.0.1" /> <property name="port" value="6379" /> <property name="timeout" value="3000" /> <property name="usePool" value="true" /> <property name="poolConfig" ref="jedisPoolConfig" /> </bean></beans>
4.index.jsp简单的读取一下sessioid
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body> jsessionid=${pageContext.session.id} <br /> <%=request.getRealPath("/")%></body></html>结果:
启动tomcat访问之后查看页面:
可视化界面查看redis库中的数据:
redis中的key:
可视化界面中查看:
在redis中通过flushall清空所有数据之后再次刷新界面发现重新生成sessionid，确实是与redis中session同步。
补充:这里需要注意，如果需要在session中存bean的话，bean需要实现Serializable接口。
例如:
package sessionDemo;import java.io.Serializable;public class User implements Serializable { /** * */ private static final long serialVersionUID = -5654418863461227475L; private String username; private int age; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public static long getSerialversionuid() { return serialVersionUID; } public User(String username, int age) { super(); this.username = username; this.age = age; }}
修改页面:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@ page import="sessionDemo.*"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body> <% request.getSession().setAttribute("user", new User("zs", 5)); %> jsessionid=${pageContext.session.id} <br /> ${user.username} <br /> <%=request.getRealPath("/")%></body></html>
访问页面查看效果:
查看redis:
源码地址:https://github.com/qiao-zhi/spring-session-redis
补充:关于org.springframework.web.filter.DelegatingFilterProxy过滤器的使用
DelegatingFilterProxy就是一个对于servlet filter的代理，用这个类的好处主要是通过Spring容器来管理servlet filter的生命周期，还有就是如果filter中需要一些Spring容器的实例，可以通过spring直接注入，另外读取一些配置文件这些便利的操作都可以通过Spring来配置实现。
DelegatingFilterProxy的使用方法:
首先在web.xml中配置：
<filter>< filter-name>filterName</filter-name>< filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class></filter><filter-mapping>< filter-name>filterName</filter-name>< url-pattern>/*</url-pattern></filter-mapping>
然后在Spring的配置文件中，配置具体的Filter类的实例。
<bean name="filterName" class="com.*.Filter"></bean>
在Spring中配置的bean的name要和web.xml中的<filter-name>一样
或者在DelegatingFilterProxy的filter配置中配置初始参数：targetBeanName，对应到Spring配置中的beanname
如果要保留Filter原有的init，destroy方法的调用，还需要配置初始化参数targetFilterLifecycle为true，该参数默认为false
在上面session的过滤器使用中，我们在web.xml中配置的filter的name为:springSessionRepositoryFilter,所以spring容器中应该有bean为springSessionRepositoryFilter的过滤器。查阅源码发现如下:SpringHttpSessionConfiguration 类中。(下面是spring4.0提倡的java配置方式，方法的名称就是bean的name,@Bean生命一个bean)
@Bean public <S extends ExpiringSession> SessionRepositoryFilter<? extends ExpiringSession> springSessionRepositoryFilter( SessionRepository<S> sessionRepository) { SessionRepositoryFilter<S> sessionRepositoryFilter = new SessionRepositoryFilter<S>( sessionRepository); sessionRepositoryFilter.setServletContext(this.servletContext); if (this.httpSessionStrategy instanceof MultiHttpSessionStrategy) { sessionRepositoryFilter.setHttpSessionStrategy( (MultiHttpSessionStrategy) this.httpSessionStrategy); } else { sessionRepositoryFilter.setHttpSessionStrategy(this.httpSessionStrategy); } return sessionRepositoryFilter; }
注意下面红色部分的配置，nginx监听84端口，采用权重的方式分别分发到本机的85端口和86端口。85端口和86端口分别启动两个tomcat并且部署上面的项目。
#user nobody;worker_processes 1;#error_log logs/error.log;#error_log logs/error.log notice;#error_log logs/error.log info;#pid logs/nginx.pid;events { worker_connections 1024;}http { include mime.types; default_type application/octet-stream; #log_format main '$remote_addr - $remote_user [$time_local] "$request" ' # '$status $body_bytes_sent "$http_referer" ' # '"$http_user_agent" "$http_x_forwarded_for"'; #access_log logs/access.log main; sendfile on; #tcp_nopush on; #keepalive_timeout 0; keepalive_timeout 65; #gzip on; server { listen 84; server_name localhost; #charset koi8-r; #access_log logs/host.access.log main; location / { proxy_connect_timeout 3; proxy_send_timeout 30; proxy_read_timeout 30; proxy_pass http://clustername; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root html; } # proxy the PHP scripts to Apache listening on 127.0.0.1:80 # #location ~ \.php$ { # proxy_pass http://127.0.0.1; #} # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000 # #location ~ \.php$ { # root html; # fastcgi_pass 127.0.0.1:9000; # fastcgi_index index.php; # fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name; # include fastcgi_params; #} # deny access to .htaccess files, if Apache's document root # concurs with nginx's one # #location ~ /\.ht { # deny all; #} } # another virtual host using mix of IP-, name-, and port-based configuration # #server { # listen 8000; # listen somename:8080; # server_name somename alias another.alias; # location / { # root html; # index index.html index.htm; # } #} #集群配置：服务器列表 upstream clustername { server 127.0.0.1:85 weight=1;#服务器配置 server 127.0.0.1:86 weight=1;#服务器配置 } # HTTPS server # #server { # listen 443 ssl; # server_name localhost; # ssl_certificate cert.pem; # ssl_certificate_key cert.key; # ssl_session_cache shared:SSL:1m; # ssl_session_timeout 5m; # ssl_ciphers HIGH:!aNULL:!MD5; # ssl_prefer_server_ciphers on; # location / { # root html; # index index.html index.htm; # } #}}
测试:访问nginx的84端口，多次访问发现平均是一次85端口的tomcat、一次86端口的tomcat，并且其session不变，也就是两个tomcat共用一个redis的session，实现了session共享。
至此完成了redis spring-session实现了session共享，并且也简单的实现了结合nginx实现集群 session共享。
接下来还会研究shiro redis的session共享。
关于nginx的ip_hash实现根据ip分发到对应server，参考:https://www.cnblogs.com/qlqwjy/p/9833669.html
来源：http://www.icode9.com/content-2-114451.html
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