tomcat - 技术栈

一、tomcat介绍

Tomcat 是由 Apache 软件基金会（Apache Software Foundation）开发的一款开源、轻量级的 Java Web 服务器，同时也是最常用的 Servlet 容器（Servlet Container）。它主要用于部署和运行基于 Java 的 Web 应用程序，是 Java EE（现 Jakarta EE）生态中不可或缺的基础组件。

安装java

bash 复制代码

#安装java环境

[root@localhost ~]# dnf install java-1.8.0-openjdk.x86_64 -y

#查看java版本

[root@localhost ~]# java -version
openjdk version "1.8.0_402"
OpenJDK Runtime Environment (build 1.8.0_402-b06)
OpenJDK 64-Bit Server VM (build 25.402-b06, mixed mode)
[root@localhost ~]# which java
/usr/bin/java
[root@localhost ~]# ll /usr/bin/java
lrwxrwxrwx. 1 root root 22  7月 30 11:05 /usr/bin/java -> /etc/alternatives/java
[root@localhost ~]# cd /etc/alternatives/jre
[root@localhost jre]# ls
ASSEMBLY_EXCEPTION  bin  lib  LICENSE  THIRD_PARTY_README

安装tomcat

bash 复制代码

[root@localhost ~]#  tar zxf apache-tomcat-9.0.107.tar.gz -C /usr/local/
[root@localhost ~]# cd /usr/local/
[root@localhost local]# ls
apache-tomcat-9.0.107  bin  etc  games  include  lib  lib64  libexec  sbin  share  src
[root@localhost local]# mv apache-tomcat-9.0.107/ tomcat

#启动tomcat
[root@localhost local]# cd tomcat/
[root@localhost tomcat]# cd bin/
[root@localhost bin]# ls
bootstrap.jar       ciphers.sh                    daemon.sh     setclasspath.bat  startup.sh            version.bat
catalina.bat        commons-daemon.jar            digest.bat    setclasspath.sh   tomcat-juli.jar       version.sh
catalina.sh         commons-daemon-native.tar.gz  digest.sh     shutdown.bat      tomcat-native.tar.gz
catalina-tasks.xml  configtest.bat                makebase.bat  shutdown.sh       tool-wrapper.bat
ciphers.bat         configtest.sh                 makebase.sh   startup.bat       tool-wrapper.sh
[root@localhost bin]# ./startup.sh
Using CATALINA_BASE:   /usr/local/tomcat
Using CATALINA_HOME:   /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JRE_HOME:        /usr
Using CLASSPATH:       /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar
Using CATALINA_OPTS:
Tomcat started.

#查看端口
[root@localhost ~]# netstat -tlnp | grep java
tcp6       0      0 :::8080                 :::*                    LISTEN      42487/java
tcp6       0      0 127.0.0.1:8005          :::*                    LISTEN      42487/java

访问tomcat

生成tomcat的启动文件

172.25.254.10 172.25.254.11

bash 复制代码

#生成tomcat的主配置文件

[root@localhost bin]#  vim /usr/local/tomcat/conf/tomcat.conf
JAVA_HOME=/etc/alternatives/jre

#生成启动文件

[root@localhost bin]# vim /lib/systemd/system/tomcat.service
[Unit]
Description=Tomcat
#After=syslog.target network.target remote-fs.target nss-lookup.target
After=syslog.target network.target

[Service]
Type=forking
EnvironmentFile=/usr/local/tomcat/conf/tomcat.conf
ExecStart=/usr/local/tomcat/bin/startup.sh
ExecStop=/usr/local/tomcat/bin/shutdown.sh
PrivateTmp=true
User=tomcat
Group=tomcat

[Install]
WantedBy=multi-user.target

生成tomcat用户并设定软件安装目录权限

bash 复制代码

[root@localhost bin]# useradd -s /sbin/nologin -M tomcat
[root@localhost bin]# chown tomcat.tomcat /usr/local/tomcat/ -R

开启tomcat

bash 复制代码

[root@localhost bin]#  systemctl enable --now tomcat
Created symlink /etc/systemd/system/multi-user.target.wants/tomcat.service → /usr/lib/systemd/system/tomcat.service.

二、tomcat负载均衡实现

172.25.254.100

复制代码

[root@localhost ~]# cd /etc/nginx/conf.d
[root@localhost conf.d]# ls
[root@localhost conf.d]# vim vhosts.conf
upstream tomcat{
        hash $cookie_JSESSIONID;
        server 172.25.254.10:8080;
        server 172.25.254.11:8080;
}
server {
        listen 80;
        server_name www.wan.org;
        location ~ \/jsp$ {
                proxy_pass http://tomcat;
        }
}
[root@localhost conf.d]# nginx -t
[root@localhost conf.d]# nginx -s reload

172.25.254.10 172.25.254.11

test.jsp

bash 复制代码

<%@ page contentType="text/html; charset=GBK" %>
<%@ page import="java.util.*" %>
<html><head><title>Cluster App Test</title></head>
<body>
Server Info:
<%
out.println(request.getLocalAddr() + " : " + request.getLocalPort()+"<br>");%>
<%
out.println("<br> ID " + session.getId()+"<br>");
String dataName = request.getParameter("dataName");
if (dataName != null && dataName.length() > 0) {
String dataValue = request.getParameter("dataValue");
session.setAttribute(dataName, dataValue);
}
out.print("<b>Session list</b>");
Enumeration e = session.getAttributeNames();
while (e.hasMoreElements()) {
String name = (String)e.nextElement();
String value = session.getAttribute(name).toString();
out.println( name + " = " + value+"<br>");
System.out.println( name + " = " + value);
}
%>
<form action="test.jsp" method="POST">
name:<input type=text size=20 name="dataName">
<br>
key:<input type=text size=20 name="dataValue">
<br>
<input type=submit>
</form>
</body>
</html>

172.25.254.100

负载均衡查看

三、Memcached

Memcached 是一款高性能的分布式内存对象缓存系统，提供了简单的键值对操作命令，用于快速存储和获取数据。

memcached的安装与启动

172.25.254.10 172.25.254.11

复制代码

[root@localhost ~]# yum install memcached -y
[root@localhost ~]# vim /etc/sysconfig/memcache
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="64"
OPTIONS="-l 0.0.0.0,::1"
[root@localhost ~]# systemctl enable --now memcached
Created symlink /etc/systemd/system/multi-user.target.wants/memcached.service → /usr/lib/systemd/system/memcached.service.
[root@localhost ~]# netstat -antlupe | grep memcache
tcp        0      0 0.0.0.0:11211           0.0.0.0:*               LISTEN      980        91087      46265/memcached
tcp6       0      0 ::1:11211               :::*                    LISTEN      980        91088      46265/memcached

memchahced 操作命令

set 无论键是否存在，都设置键值对。

get 获取键的值。

add 当键不存在时，添加键值对。

replace 当键存在时，更新键值对）。

delete 删除指定键。

复制代码

[root@localhost ~]# telnet localhost 11211
Trying ::1...
Connected to localhost.
Escape character is '^]'.
添加
add wankey 0 60 5          #0 是否压缩 60 过期时间 4 字长
admin
STORED
#查看
get wankey
VALUE wankey 0 5
admin
END
#修改
set wankey 0 60 4
admi
STORED
get wankey
VALUE wankey 0 4
admi
END
#删除
delete wankey
DELETED
get wankey
END
quit        #退出

四、session 共享服务器

在分布式系统中，Tomcat 的 Session 共享是一个关键问题。当多个 Tomcat 实例组成集群提供服务时，用户的请求可能被分发到不同实例，若 Session 无法共享，会导致用户状态丢失（如登录失效）。

多台 Tomcat 服务器通过负载均衡（如 Nginx）协同工作，用户会话（Session）需在所有实例间同步。

172.25.254.10 172.25.254.11

bash 复制代码

[root@localhost ~]# ls
公共  模板  视频  图片  文档  下载  音乐  桌面  anaconda-ks.cfg  apache-tomcat-9.0.107.tar.gz  jar.zip
[root@localhost ~]# unzip jar.zip
Archive:  jar.zip
   creating: jar/
  inflating: jar/asm-5.2.jar
  inflating: jar/kryo-3.0.3.jar
  inflating: jar/kryo-serializers-0.45.jar
  inflating: jar/memcached-session-manager-2.3.2.jar
  inflating: jar/memcached-session-manager-tc9-2.3.2.jar
  inflating: jar/minlog-1.3.1.jar
  inflating: jar/msm-kryo-serializer-2.3.2.jar
  inflating: jar/objenesis-2.6.jar
  inflating: jar/reflectasm-1.11.9.jar
  inflating: jar/spymemcached-2.12.3.jar
[root@localhost ~]# cd jar/
[root@localhost jar]# ls
asm-5.2.jar                memcached-session-manager-2.3.2.jar      msm-kryo-serializer-2.3.2.jar  spymemcached-2.12.3.jar
kryo-3.0.3.jar             memcached-session-manager-tc9-2.3.2.jar  objenesis-2.6.jar
kryo-serializers-0.45.jar  minlog-1.3.1.jar                         reflectasm-1.11.9.jar
[root@localhost jar]# cp *  /usr/local/tomcat/lib/
[root@localhost jar]# cd /usr/local/tomcat/lib/
[root@localhost lib]# ls
annotations-api.jar       jasper.jar                               servlet-api.jar          tomcat-i18n-ko.jar
asm-5.2.jar               jaspic-api.jar                           spymemcached-2.12.3.jar  tomcat-i18n-pt-BR.jar
catalina-ant.jar          jsp-api.jar                              tomcat-api.jar           tomcat-i18n-ru.jar
catalina-ha.jar           kryo-3.0.3.jar                           tomcat-coyote-ffm.jar    tomcat-i18n-zh-CN.jar
catalina.jar              kryo-serializers-0.45.jar                tomcat-coyote.jar        tomcat-jdbc.jar
catalina-ssi.jar          memcached-session-manager-2.3.2.jar      tomcat-dbcp.jar          tomcat-jni.jar
catalina-storeconfig.jar  memcached-session-manager-tc9-2.3.2.jar  tomcat-i18n-cs.jar       tomcat-util.jar
catalina-tribes.jar       minlog-1.3.1.jar                         tomcat-i18n-de.jar       tomcat-util-scan.jar
ecj-4.20.jar              msm-kryo-serializer-2.3.2.jar            tomcat-i18n-es.jar       tomcat-websocket.jar
el-api.jar                objenesis-2.6.jar                        tomcat-i18n-fr.jar       websocket-api.jar
jasper-el.jar             reflectasm-1.11.9.jar                    tomcat-i18n-ja.jar

#172.25.254.10
[root@localhost lib]# vim /usr/local/tomcat/conf/context.xml
     <Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
     memcachedNodes="n1:172.25.254.10:11211,n2:172.25.254.20:11211"
     failoverNodes="n1"
     requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"               transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"
   />

#172.25.254.11
[root@localhost lib]# vim /usr/local/tomcat/conf/context.xml
     <Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
     memcachedNodes="n1:172.25.254.10:11211,n2:172.25.254.20:11211"
     failoverNodes="n2"
     requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"               transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"
   />

测试

172.25.254.100

1.在两台tomcat都开启的情况下： http://www.wan.org/test.jsp

2.在n1被停止后继续提交信息看是否可以读取到之前的会话信息