Tomcat通过Redis实现session共享的完整部署记录

对于生产环境有了一定规模的tomcat集群业务来说,要实现session会话共享,比较稳妥的方式就是使用数据库持久化session.为什么要持久化session（共享session）呢？因为在客户端每个用户的Session对象存在Servlet容器中，如果Tomcat服务器重启或者宕机的话，那么该session就会丢失，而客户端的操作会由于session丢失而造成数据丢失；如果当前用户访问量巨大，每个用户的Session里存放大量数据的话，那么就很占用服务器大量的内存，进而致使服务器性能受到影响。数据库持久化session，分为物理数据库和内存数据库。物理数据库备份session，由于其性能原因，不推荐；内存数据库可以使用redis和memcached，之前已经介绍了memcached方式实现session共享了,下面说下redis方式:

但是有一点需要清楚:就是Redis这种方式目前还暂不支持Tomcat8环境(因为现在网上插件不支持tomcat8,非要支持tomcat8,则需修改插件jar包的源代码)!下面就先说下Tomcat7+Redis+Nginx实现session会话共享的操作记录:

实现达到的效果
当客户端访问Nginx服务器时，Nginx负载均衡会自动将请求转发到Tomcat1节点或Tomcat2节点服务器，以减轻Tomcat压力，从而达到Tomcat集群化部署，为了使各Tomcat之间共享同一个Session，将采用Redis缓存服务来集中管理Session存储。Nginx实现负载均衡，并使用Redis实现session共享。本案例采用的是redis单点方式(可以给这个redis节点配置一个从节点,采用redis主从模式,连接redis的master节点.redis默认不支持主主模式)，如果使用redis集群方式,则采用Sentinels连接。

1) 基础信息

ip                 主机名           应用                       端口
192.168.10.200     Nginx-node       nginx1.12.2                80
192.168.10.201     Tomcat-node1     java8.131、tomcat7.0.90    8080
192.168.10.202     Tomcat-node2     java8.131、tomcat7.0.90    8080
192.168.10.203     redis-node       redis4.0.1                6379

下面操作在三台机器上同样执行：
[root@Nginx-node ~]# cat /etc/redhat-release
CentOS release 6.9 (Final)
    
为了方便测试，关闭iptables防火墙和selinux。如果是生产环境，开启iptables后，需要开放对应的应用端口。
[root@Nginx-node ~]# setenforce 0
[root@Nginx-node ~]# getenforce
disabled
[root@Nginx-node ~]# cat /etc/sysconfig/selinux |grep "SELINUX=disabled"
SELINUX=disabled
[root@Nginx-node ~]# /etc/init.d/iptables stop

本案例环境部署中所需的软件下载地址：https://pan.baidu.com/s/1f9GM4iVAzfJsjskpAwv8Og
提取密码:dsfs
下载到服务器上的/usr/local/src目录下.另外:节点服务器的系统时间一定要保持一致!!

2) 安装Nginx（在192.168.10.200机器上操作）

[root@Nginx-node ~]# cd /usr/local/src/
[root@Nginx-node src]# ll
total 8920
-rw-rw-r--. 1 root root  981687 Oct 27  2017 nginx-1.12.2.tar.gz
-rw-rw-r--. 1 root root 5453234 Aug 23  2018 openssl-1.1.0i.tar.gz
-rw-rw-r--. 1 root root 2081413 Aug 23  2018 pcre-8.42.tar.gz
-rw-rw-r--. 1 root root  607698 Jan 16  2017 zlib-1.2.11.tar.gz
 
安装依赖包
[root@Nginx-node src]# yum -y install gcc gcc-c++
 
安装pcre库
[root@Nginx-node src]# tar -zvxf pcre-8.42.tar.gz
[root@Nginx-node src]# cd pcre-8.42
[root@Nginx-node pcre-8.42]# ./configure && make && make install
 
安装zlib库
[root@Nginx-node pcre-8.42]# cd /usr/local/src/
[root@Nginx-node src]# tar -zvxf zlib-1.2.11.tar.gz
[root@Nginx-node src]# cd zlib-1.2.11
[root@Nginx-node zlib-1.2.11]# ./configure && make && make install
 
安装openssl
[root@Nginx-node zlib-1.2.11]# cd /usr/local/src/
[root@Nginx-node src]# tar -zvxf openssl-1.1.0i.tar.gz
[root@Nginx-node src]# cd openssl-1.1.0i
[root@Nginx-node openssl-1.1.0i]# ./config && make && make install
 
安装nginx，特别注意要指定prce zlib openssl原码包位置
[root@Nginx-node openssl-1.1.0i]# cd /usr/local/src/
[root@Nginx-node src]# tar -zvxf nginx-1.12.2.tar.gz
[root@Nginx-node src]# cd nginx-1.12.2                
[root@Nginx-node nginx-1.12.2]# ./configure --prefix=/usr/local/nginx --with-http_ssl_module --with-pcre=/usr/local/src/pcre-8.42 --with-zlib=/usr/local/src/zlib-1.2.11  --with-openssl=/usr/local/src/openssl-1.1.0i
[root@Nginx-node nginx-1.12.2]# make && make install
 
安装成功后配置nginx
[root@Nginx-node nginx-1.12.2]# cd /usr/local/nginx/conf/
[root@Nginx-node conf]# cp nginx.conf nginx.conf.bak
[root@Nginx-node conf]# cat nginx.conf
#user  nobody;
worker_processes  8;
  
#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;
  
#pid        logs/nginx.pid;
  
worker_rlimit_nofile 65535;
events {
   use epoll;
    worker_connections  65535;
}
  
http {
    include       mime.types;
    default_type  application/octet-stream;
    charset utf-8;
          
    ######
    ## set access log format
    ######
    log_format  main  '$http_x_forwarded_for $remote_addr $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_cookie" $host $request_time';
  
    #######
    ## http setting
    #######
    sendfile       on;
    tcp_nopush     on;
    tcp_nodelay    on;
    keepalive_timeout  65;
    fastcgi_connect_timeout 30000;
    fastcgi_send_timeout 30000;
    fastcgi_read_timeout 30000;
    fastcgi_buffer_size 256k;
    fastcgi_buffers 8 256k;
    fastcgi_busy_buffers_size 256k;
    fastcgi_temp_file_write_size 256k;
    fastcgi_intercept_errors on;
  
    ##cache##
    client_header_timeout 60s;
    client_body_timeout 60s;
    client_max_body_size 10m;
    client_body_buffer_size 1m;
    proxy_connect_timeout 5;
    proxy_read_timeout 60;
    proxy_send_timeout 5;             
    proxy_buffer_size 64k;
    proxy_buffers 4 128k;
    proxy_busy_buffers_size 128k;
    proxy_temp_file_write_size 1m;
    proxy_temp_path /home/temp_dir;
    proxy_cache_path /home/cache levels=1:2 keys_zone=cache_one:200m inactive=1d max_size=30g;
    ##end##
  
    gzip  on;
    gzip_min_length  1k;
    gzip_buffers     4 16k;
    gzip_http_version 1.1;
    gzip_comp_level 9;
    gzip_types       text/plain application/x-javascript text/css application/xml text/javascript application/x-httpd-php;
    gzip_vary on;
  
    ## includes vhosts
    include vhosts/*.conf;
}
 
[root@Nginx-node conf]# mkdir vhosts
[root@Nginx-node conf]# cd vhosts/
[root@Nginx-node vhosts]# vim lb_tomcat.conf
  upstream tomcat-lb {
      server 192.168.10.201:8080;
      server 192.168.10.202:8080;
      }
                    
      server {
      listen  80;
      server_name www.kevin.com;
      location / {
          proxy_pass http://tomcat-lb;
          proxy_set_header  X-Real-IP $remote_addr;
          proxy_set_header  REMOTE-HOST $remote_addr;
          proxy_set_header  Host $host;
          proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
        }
        location ~ .*.(gif|jpg|png|htm|html|css|ico|flv|swf)(.*) {
              proxy_pass http://tomcat-lb;
              proxy_redirect off;
              proxy_set_header Host $host;
              proxy_cache cache_one;
              proxy_cache_valid 200 302 1h;
              proxy_cache_valid 301 1d;
              proxy_cache_valid any 10m;
              expires 30d;
              proxy_cache_key $host$uri$is_args$args;
        }
}
 
[root@Nginx-node vhosts]# /usr/local/nginx/sbin/nginx -t
nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful
[root@Nginx-node conf]# /usr/local/nginx/sbin/nginx
[root@Nginx-node conf]# lsof -i:80
COMMAND   PID   USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
nginx   25292   root    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25293 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25294 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25295 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25296 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25297 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25298 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25299 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
nginx   25300 nobody    6u  IPv4 19679665      0t0  TCP *:http (LISTEN)
 
将域名www.kevin.com解析到192.168.10.200上，访问http://www.kevin.com，发现访问请求结果会负载到192.168.10.201和192.168.10.202的tomcat上了。

3）安装tomcat（在192.168.10.201和192.168.10.202两台机器上操作）

安装java8环境。先卸载掉系统自带的java7，然后安装java8
[root@Tomcat-node1 ~]# java -version
java version "1.7.0_131"
OpenJDK Runtime Environment (rhel-2.6.9.0.el6_8-x86_64 u131-b00)
OpenJDK 64-Bit Server VM (build 24.131-b00, mixed mode)
[root@Tomcat-node1 ~]# yum -y remove java-1.7.0-openjdk*
[root@Tomcat-node1 ~]# yum -y remove tzdata-java.noarch
[root@Tomcat-node1 ~]# java -version                 
-bash: /usr/bin/java: No such file or directory
   
[root@Tomcat-node1 ~]# ll /usr/local/src/jdk-8u131-linux-x64_.rpm
-rw-rw-r--. 1 root root 169983496 Nov 19  2017 /usr/local/src/jdk-8u131-linux-x64_.rpm
[root@Tomcat-node1 ~]# rpm -ivh /usr/local/src/jdk-8u131-linux-x64_.rpm --force
[root@Tomcat-node1 ~]# vim /etc/profile
......
JAVA_HOME=/usr/java/jdk1.8.0_131
JAVA_BIN=/usr/java/jdk1.8.0_131/bin
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin:/bin:/sbin/
CLASSPATH=.:/lib/dt.jar:/lib/tools.jar
export JAVA_HOME JAVA_BIN PATH CLASSPATH
   
[root@Tomcat-node1 ~]# source /etc/profile
[root@Tomcat-node1 ~]# java -version
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)
You have new mail in /var/spool/mail/root
   
安装配置tomcat7
[root@Tomcat-node1 ~]# cd /usr/local/src/
[root@Tomcat-node1 src]# ll apache-tomcat-7.0.90.tar.gz
-rw-rw-r--. 1 root root 9472492 Nov  9  2017 apache-tomcat-7.0.90.tar.gz
[root@Tomcat-node1 src]# tar -zvxf apache-tomcat-7.0.90.tar.gz
[root@Tomcat-node1 src]# mv apache-tomcat-7.0.90 /usr/local/tomcat7
   
配置tomcat7
[root@Tomcat-node1 ~]# cd /usr/local/tomcat7/conf/
[root@Tomcat-node1 conf]# cp server.xml server.xml.bak
[root@Tomcat-node1 conf]# vim server.xml
.......
 <Engine name="Catalina" defaultHost="localhost">                #这一行不需要修改,没必要动
.......
 <Host name="localhost" appBase="/data/webapps/" unpackWARS="true" autoDeploy="true">
        <Context path="" docBase="/data/webapps" reloadable="true" />
......
        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="/data/logs"
               prefix="web1_access_log." suffix=".txt"
               pattern="%h %l %u %t "%r" %s %b" />
  </Host>


创建项目目录
[root@Tomcat-node1 conf]# mkdir -p /data/webapps/{WEB-INF,META-INF,classes,lib}
[root@Tomcat-node1 conf]# mkdir /data/logs

创建测试文件
[root@Tomcat-node1 ~]# touch /data/webapps/index.jsp 
[root@Tomcat-node1 ~]# vim /data/webapps/index.jsp         
<html>
    <body bgcolor="green">     
    <center>    
    <%=  request.getSession().getId()  %>    
    <h1>192.168.10.201</h1>
    <h1>port:8080</h1>
    <h1>this is Tomcat-node1! </h1> 
    </center>
    </body>
</html>
 
<%@ page contentType="text/html;charset=UTF-8" isELIgnored="false"%>
SessionID:<%=session.getId()%><BR>
SessionIP:<%=request.getServerName()%> <BR>
SessionPort:<%=request.getServerPort()%>
<%     out.println("This is Tomcat server 201 !");     %>
You have new mail in /var/spool/mail/root


另一个节点的测试文件为:
[root@Tomcat-node2 ~]# vim /data/webapps/index.jsp 
<html>
    <body bgcolor="yellow">     
    <center>    
    <%=  request.getSession().getId()  %>    
    <h1>192.168.10.202</h1>
    <h1>port:8080</h1>
    <h1>this is Tomcat-node2! </h1> 
    </center>
    </body>
</html>
 
<%@ page contentType="text/html;charset=UTF-8" isELIgnored="false"%>
SessionID:<%=session.getId()%><BR>
SessionIP:<%=request.getServerName()%> <BR>
SessionPort:<%=request.getServerPort()%>
<%     out.println("This is Tomcat server 202 !");     %>


接着配置Redis+Session共享
[root@Tomcat-node1 ~]# cd /usr/local/tomcat7/conf/
[root@Tomcat-node1 conf]# cp context.xml context.xml.bak 
[root@Tomcat-node1 conf]# cat context.xml
......
    <Valve className="com.orangefunction.tomcat.redissessions.RedisSessionHandlerValve" />  
    <Manager className="com.orangefunction.tomcat.redissessions.RedisSessionManager"  
             host="192.168.10.203"  
             port="6379"  
             database="0" 
             maxInactiveInterval="60" />


===============================================================
温馨提示:
如果远程redis设置了密码,则就多加一行配置:password="123456"
===============================================================


最后将依赖的三个jar包拷贝到tomcat7的lib目录下
[root@Tomcat-node1 jar]# pwd
/usr/local/src/tomcat_redis_session/jar
[root@Tomcat-node1 jar]# ll
total 676
-rw-rw-r--. 1 root root 111969 Jul 29  2015 commons-pool2-2.4.2.jar
-rw-rw-r--. 1 root root 553762 Oct 16  2017 jedis-2.9.0.jar
-rw-rw-r--. 1 root root  20241 Aug 27 16:45 tomcat-redis-session-manager1.2.jar
[root@Tomcat-node1 jar]# cp -rf ./* /usr/local/tomcat7/lib/


启动tomcat
[root@Tomcat-node1 src]# /usr/local/tomcat8/bin/startup.sh
Using CATALINA_BASE:   /usr/local/tomcat8
Using CATALINA_HOME:   /usr/local/tomcat8
Using CATALINA_TMPDIR: /usr/local/tomcat8/temp
Using JRE_HOME:        /usr/java/jdk1.8.0_131
Using CLASSPATH:       /usr/local/tomcat8/bin/bootstrap.jar:/usr/local/tomcat8/bin/tomcat-juli.jar
Tomcat started.
You have new mail in /var/spool/mail/root
[root@Tomcat-node1 src]# ps -ef|grep tomcat
root      8477     1 87 03:11 pts/0    00:00:03 /usr/java/jdk1.8.0_131/bin/java -Djava.util.logging.config.file=/usr/local/tomcat8/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -classpath /usr/local/tomcat8/bin/bootstrap.jar:/usr/local/tomcat8/bin/tomcat-juli.jar -Dcatalina.base=/usr/local/tomcat8 -Dcatalina.home=/usr/local/tomcat8 -Djava.io.tmpdir=/usr/local/tomcat8/temp org.apache.catalina.startup.Bootstrap start
root      8528  6829  0 03:11 pts/0    00:00:00 grep tomcat
[root@Tomcat-node1 src]# lsof -i:8080
COMMAND  PID USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
java    8477 root   49u  IPv6 12974768      0t0  TCP *:webcache (LISTEN)

4) redis安装

[root@redis-node ~]# cd /usr/local/src/
[root@redis-node src]# ll redis-4.0.1.tar.gz 
-rw-rw-r-- 1 root root 1711660 Aug 27 16:19 redis-4.0.1.tar.gz

编写redis一键安装脚本
[root@redis-node src]# cat redis_install.sh 
#!/usr/bin/env bash
# It's Used to be install redis.
# Created on 2018/08/27 11:18.
# @author: wangshibo.
# Version: 1.0
   
function install_redis () {
#################################################################################################
        cd /usr/local/src
        tar -zxvf /usr/local/src/redis-4.0.1.tar.gz
        cd redis-4.0.1
        make PREFIX=/usr/local/redis install
        mkdir -p /usr/local/redis/{etc,var}
        rsync -avz redis.conf  /usr/local/redis/etc/
        sed -i 's@pidfile.*@pidfile /var/run/redis-server.pid@' /usr/local/redis/etc/redis.conf
        sed -i "s@logfile.*@logfile /usr/local/redis/var/redis.log@" /usr/local/redis/etc/redis.conf
        sed -i "s@^dir.*@dir /usr/local/redis/var@" /usr/local/redis/etc/redis.conf
        sed -i 's/daemonize no/daemonize yes/g' /usr/local/redis/etc/redis.conf
        sed -i 's/^# bind 127.0.0.1/bind 0.0.0.0/g' /usr/local/redis/etc/redis.conf
 #################################################################################################
}
   
install_redis


赋予脚本执行权限,并进行安装
[root@redis-node src]# chmod 755 /usr/local/src/redis_install.sh
[root@redis-node src]# /bin/bash -x /usr/local/src/redis_install.sh


编写redis-server启动脚本
[root@redis-node src]# cat /etc/init.d/redis-server 
#!/bin/bash
#
# redis - this script starts and stops the redis-server daemon
#
# chkconfig:   - 85 15
# description:  Redis is a persistent key-value database
# processname: redis-server
# config:      /usr/local/redis/etc/redis.conf
# config:      /etc/sysconfig/redis
# pidfile:     /usr/local/redis/var/redis-server.pid
  
# Source function library.
. /etc/rc.d/init.d/functions
  
# Source networking configuration.
. /etc/sysconfig/network
  
# Check that networking is up.
[ "$NETWORKING" = "no" ] && exit 0
  
redis="/usr/local/redis/bin/redis-server"
prog=$(basename $redis)
  
REDIS_CONF_FILE="/usr/local/redis/etc/redis.conf"
  
[ -f /etc/sysconfig/redis ] && . /etc/sysconfig/redis
  
lockfile=/var/lock/subsys/redis-server
  
start() {
    [ -x $redis ] || exit 5
    [ -f $REDIS_CONF_FILE ] || exit 6
    echo -n $"Starting $prog: "
    daemon $redis $REDIS_CONF_FILE
    retval=$?
    echo
    [ $retval -eq 0 ] && touch $lockfile
    return $retval
}
  
stop() {
    echo -n $"Stopping $prog: "
    killproc $prog
    retval=$?
    echo
    [ $retval -eq 0 ] && rm -f $lockfile
    return $retval
}
  
restart() {
    stop
    start
}
  
reload() {
    echo -n $"Reloading $prog: "
    killproc $redis -HUP
    RETVAL=$?
    echo
}
  
force_reload() {
    restart
}
  
rh_status() {
    status $prog
}
  
rh_status_q() {
    rh_status >/dev/null 2>&1
}
  
case "$1" in
    start)
        rh_status_q && exit 0
        $1
        ;;
    stop)
        rh_status_q || exit 0
        $1
        ;;
    restart)
        $1
        ;;
    reload)
        rh_status_q || exit 7
        $1
        ;;
    force-reload)
        force_reload
        ;;
    status)
        rh_status
        ;;
    condrestart|try-restart)
        rh_status_q || exit 0
            ;;
    *)
        echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload}"
        exit 2
esac


赋予脚本执行权限,并启动redis-server
[root@redis-node src]# /etc/init.d/redis-server start
[root@redis-node src]# lsof -i:6379
COMMAND     PID USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
redis-ser 24439 root    6u  IPv4 24642923      0t0  TCP dns02.kevin.cn:6379 (LISTEN)

温馨提示:
需要将redis.conf文件中的bind改为本机ip.不能使用默认的127.0.0.1,否则远程连接该redis就会失败
[root@redis-node src]# vim /usr/local/redis/etc/redis.conf
.....
bind 192.168.10.203

重启redis-server服务
[root@redis-node src]# /etc/init.d/redis-server restart
Stopping redis-server:                                     [  OK  ]
Starting redis-server:                                     [  OK  ]
[root@redis-node src]# lsof -i:6379
COMMAND    PID USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
redis-ser 8184 root    6u  IPv4 24688720      0t0  TCP dns02.kevin.cn:6379 (LISTEN)

最好在tomcat两个节点上使用"telnet 192.168.10.203 6379"验证下redis是否能成功连接

5) tomcat通过redis共享session测试
访问http://www.kevin.com,不断刷新页面,发现页面的其他信息改变,但是sessionid保持不变,即说明实现了session共享!

关闭两个节点中的任意一个tomcat服务,继续访问页面,发现sessionid任然保持不变!

然后在redis机器上查看有没有上面sessionid的key值存在

[root@redis-node ~]# /usr/local/redis/bin/redis-cli -h 192.168.10.203 -p 6379
192.168.10.203:6379> keys *
1) "F7FE0AE8BD1654584A330A804A7BE5FE"
192.168.10.203:6379> 

========================================================================
上面采用的是redis单节点方式(主从模式),如果是redis集群方式,则采用"Nginx+Tomcat + Redis Sentinel",大致操作如下:

1) 部署Redis+redis集群,参考文档:https://www.cnblogs.com/kevingrace/p/9004460.html
2) redis集群方式的session共享配置为(conf/context.xml):
    <Valve className="com.orangefunction.tomcat.redissessions.RedisSessionHandlerValve" />
    <Manager className="com.orangefunction.tomcat.redissessions.RedisSessionManager"
             sentinels="192.168.9.223:30001,192.168.9.223:30002" />          #这里是redis哨兵的地址,多个sentinels集群就写多个ip地址
             maxInactiveInterval="60"
             sentinelMaster="mymaster"                                       #这里是sentinel的master名称，一定不要写错
             password="123456"                                               #还有认证密码

Tomcat+Redis Sentinel工作原理:
原此时我们连接的不在是redis主从,而是直接连接哨兵，哨兵会监测后端的redis主从，当主挂掉之后，会挑选一台从当主机，然后在自身的状态中更新，此时，就不用担心主挂掉之后，IP飘移的问题了，哨兵可以多个，当某个哨兵挂掉也不会影响。

网络拓扑图如下:

========================================================================
上面的redis session会话共享方式只适用于tomcat7(现有的插件不支持tomcat8),如果非要支持tomcat8,则需要稍微改动些源码才可以支持了!
tomcat8.5+redis实现session共享所需要的jar包下载地址如下：https://pan.baidu.com/s/10VGLX-Rxuu-gmGuIOskGRQ
提取密码：tqny

其中：
tomcat-redis-session-manager-master-2.0.0.jar 包的源码经过修改，支持tomcat！
本案例使用的是tomcat8.5环境（只要是tomcat8.x版本，都可以！），测试这些jar包，完全可以实现session共享！！！

下载如下三个jar包，放到/usr/local/tomcat8/lib目录下：
commons-pool2-2.3.jar
jedis-2.7.3.jar
tomcat-redis-session-manager-master-2.0.0.jar

然后修改/usr/local/tomcat8/conf/context.xml文件，添加如下几行：

    <Valve className="com.naritech.nicole.gump.RedisSessionHandlerValve" />
    <Manager className="com.naritech.nicole.gump.RedisSessionManager"
        host="192.168.10.203"
        port="6379"
        database="0"
        maxInactiveInterval="60"
     />

案例中配置如下：

[root@Tomcat-node1 ~]# cat /usr/local/tomcat8/conf/context.xml 
<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- The contents of this file will be loaded for each web application -->
<Context>

    <!-- Default set of monitored resources. If one of these changes, the    -->
    <!-- web application will be reloaded.                                   -->
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>
    <Valve className="com.naritech.nicole.gump.RedisSessionHandlerValve" />
    <Manager className="com.naritech.nicole.gump.RedisSessionManager"
        host="192.168.10.203"
        port="6379"
        database="0"
        maxInactiveInterval="60"
     />
    <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <!--
    <Manager pathname="" />
    -->
</Context>

重启tomcat服务

[root@Tomcat-node1 ~]# chmod 755 /usr/local/tomcat8/bin/*
[root@Tomcat-node1 ~]# ps -ef|grep tomcat|awk '{print $2}'|xargs kill -9
[root@Tomcat-node1 ~]# /usr/local/tomcat8/bin/startup.sh                
[root@Tomcat-node1 ~]# lsof -i:8080
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
java    13439 root   50u  IPv6 685905      0t0  TCP *:webcache (LISTEN)

最后访问http://www.kevin.com页面，不断刷新，发现页面内容发生改变了，但是sessionid一直不变！说明实现了session共享！！！