關(guān)于session共享的方式有多種:

(1)通過nginx的ip_hash，根據(jù)ip將請求分配到對應(yīng)的服務(wù)器

(2)基于關(guān)系型數(shù)據(jù)庫存儲

(3)基于cookie存儲

(4)服務(wù)器內(nèi)置的session復(fù)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種方式，基于nosql存儲session。

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　　其實(shí)實(shí)現(xiàn)原理也比較簡單，在所有的請求之前配置一過濾器，在請求之前操作session，其實(shí)spring-session中真正起作用的session過濾器是:SessionRepositoryFilter。spring-session集成了redis與mongodb。

===========session存到redis中的研究==========

1.添加maven依賴

<project xmlns="http://maven./POM/4.0.0" xmlns:xsi="http://www./2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven./POM/4.0.0 http://maven./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>

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2.web.xml添加過濾器

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www./2001/XMLSchema-instance"
    xmlns="http://java./xml/ns/javaee"
    xsi:schemaLocation="http://java./xml/ns/javaee http://java./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監(jiān)聽器 -->
    <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>

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3.springMVC.xml配置bean

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www./schema/beans"
    xmlns:xsi="http://www./2001/XMLSchema-instance" xmlns:p="http://www./schema/p"
    xmlns:context="http://www./schema/context"
    xmlns:mvc="http://www./schema/mvc" xmlns:aop="http://www./schema/aop"
    xsi:schemaLocation="http://www./schema/beans http://www./schema/beans/spring-beans-4.2.xsd http://www./schema/context http://www./schema/context/spring-context-4.2.xsd http://www./schema/mvc http://www./schema/mvc/spring-mvc-4.0.xsd http://www./schema/aop http://www./schema/aop/spring-aop-4.2.xsd ">


    <!--1.掃描controller注解(只是掃描@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>

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4.index.jsp簡單的讀取一下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./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>

結(jié)果:

啟動tomcat訪問之后查看頁面:

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可視化界面查看redis庫中的數(shù)據(jù):

redis中的key:

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可視化界面中查看:

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?在redis中通過flushall清空所有數(shù)據(jù)之后再次刷新界面發(fā)現(xiàn)重新生成sessionid，確實(shí)是與redis中session同步。

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補(bǔ)充:這里需要注意，如果需要在session中存bean的話，bean需要實(shí)現(xiàn)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;
    }

}

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修改頁面:

<%@ 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./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>

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訪問頁面查看效果:

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查看redis:

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源碼地址:https://github.com/qiao-zhi/spring-session-redis

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?補(bǔ)充:關(guān)于org.springframework.web.filter.DelegatingFilterProxy過濾器的使用

?　　DelegatingFilterProxy就是一個(gè)對于servlet filter的代理，用這個(gè)類的好處主要是通過Spring容器來管理servlet filter的生命周期，還有就是如果filter中需要一些Spring容器的實(shí)例，可以通過spring直接注入，另外讀取一些配置文件這些便利的操作都可以通過Spring來配置實(shí)現(xiàn)。

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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>

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然后在Spring的配置文件中，配置具體的Filter類的實(shí)例。

<bean name="filterName" class="com.*.Filter"></bean>

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在Spring中配置的bean的name要和web.xml中的<filter-name>一樣

或者在DelegatingFilterProxy的filter配置中配置初始參數(shù)：targetBeanName，對應(yīng)到Spring配置中的beanname

如果要保留Filter原有的init，destroy方法的調(diào)用，還需要配置初始化參數(shù)targetFilterLifecycle為true，該參數(shù)默認(rèn)為false

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在上面session的過濾器使用中，我們在web.xml中配置的filter的name為:springSessionRepositoryFilter,所以spring容器中應(yīng)該有bean為springSessionRepositoryFilter的過濾器。查閱源碼發(fā)現(xiàn)如下:SpringHttpSessionConfiguration 類中。(下面是spring4.0提倡的java配置方式，方法的名稱就是bean的name,@Bean生命一個(gè)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;
    }

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========結(jié)合nginx實(shí)現(xiàn)集群 session共享========

1.配置nginx集群

　　注意下面紅色部分的配置，nginx監(jiān)聽84端口，采用權(quán)重的方式分別分發(fā)到本機(jī)的85端口和86端口。85端口和86端口分別啟動兩個(gè)tomcat并且部署上面的項(xiàng)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：服務(wù)器列表
    upstream clustername {
      server 127.0.0.1:85 weight=1;#服務(wù)器配置
      server 127.0.0.1:86 weight=1;#服務(wù)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;
    #    }
    #}

}

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測試:訪問nginx的84端口，多次訪問發(fā)現(xiàn)平均是一次85端口的tomcat、一次86端口的tomcat，并且其session不變，也就是兩個(gè)tomcat共用一個(gè)redis的session，實(shí)現(xiàn)了session共享。

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　　至此完成了redis spring-session實(shí)現(xiàn)了session共享，并且也簡單的實(shí)現(xiàn)了結(jié)合nginx實(shí)現(xiàn)集群 session共享。

　　接下來還會研究shiro redis的session共享。

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關(guān)于nginx的ip_hash實(shí)現(xiàn)根據(jù)ip分發(fā)到對應(yīng)server，參考:https://www.cnblogs.com/qlqwjy/p/9833669.html

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