企业级web应用服务器
解决web的应用问题

一、Tomcat 是什么?
Tomcat 是Apache 基金会 开发的一款免费、开源 的轻量级 Web 应用服务器,本质是一个 Servlet/JSP 容器(Servlet 和 JSP 是 Java Web 开发的核心技术),也是企业级 Java 开发中最常用的服务器之一。
可以简单理解为:它是运行 Java Web 项目(如网站、后台系统)的"容器",能接收浏览器的请求、处理请求(调用后端 Java 代码),并返回处理结果(如网页、数据)。
二、核心特点
- 轻量高效:体积小、配置简单、启动快,不像大型应用服务器(如JBoss、WebLogic)那样笨重,资源占用低;
- 功能适配:核心支持 Servlet、JSP、EL 表达式等 Java Web 标准技术,能满足绝大部分中小型 Java Web 项目的需求;
- 免费开源:无商业授权成本,社区活跃,问题修复和版本更新及时;
- 适用场景 :特别适合中小型系统 、并发访问用户量不多的场景(如企业内部管理系统、小型网站);高并发场景下,通常会搭配 Nginx 做反向代理,由 Nginx 处理静态资源、负载均衡,Tomcat 专注处理动态 Java 业务。
三、核心组件
- 连接器(Connector):监听指定端口(默认HTTP端口8080),接收客户端(浏览器)的请求,转发给引擎处理;
- 引擎(Engine):Tomcat 的核心处理引擎,负责将请求分发到对应的虚拟主机;
- 主机(Host):对应一个域名(如localhost),一个引擎可配置多个主机;
- 上下文(Context):对应一个具体的 Web 应用(如你的Java Web项目),是 Web 应用的运行载体。
Tomcat安装部署
1.下载安装包
bash
[root@RS1+2 ~]# wget https://dlcdn.apache.org/tomcat/tomcat-9/v9.0.115/bin/apache-tomcat-9.0.115.tar.gz
2.部署tomcat
bash
[root@RS1 local]# yum install java-1.8.0-openjdk.x86_64 -y
[root@RS1 ~]# tar zxf apache-tomcat-9.0.115.tar.gz -C /usr/local
[root@RS1 ~]# cd /usr/local/
[root@RS1 local]# ls
bin etc games include lib lib64 libexec sbin share src tomcat-9.0-doc
[root@RS1 local]# mv apache-tomcat-9.0.115/ tomcat
[root@RS1 local]# cd tomcat/
[root@RS1 tomcat]# ls
bin conf lib logs README.md RUNNING.txt webapps
BUILDING.txt CONTRIBUTING.md LICENSE NOTICE RELEASE-NOTES temp work
[root@rs1 tomcat]# cd bin/
[root@rs1 bin]# ls
[root@RS1 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.
[root@RS1 bin]# netstat -antlupe | grep 8080
tcp6 0 0 :::8080 :::* LISTEN 0 139291 10372/java
3.制作tomcat的启动脚本
bash
[root@RS1 bin]# vim /usr/local/tomcat/conf/tomcat.conf
JAVA_HOME=/etc/alternatives/jre
[root@RS1 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
[root@RS1 bin]# useradd -s /sbin/nologin -M tomcat
[root@RS1 bin]# chown tomcat.tomcat /usr/local/tomcat/ -R
[root@RS1 bin]# systemctl daemon-reload
[root@RS1 bin]# systemctl enable --now tomcat
[root@RS1 bin]# netstat -antlupe | grep java
tcp6 0 0 127.0.0.1:8005 :::* LISTEN 1000 139979 10682/java
tcp6 0 0 :::8080 :::* LISTEN 1000 140563 10682/java
4.Nginx与tomcat的整合
反向代理实现tomcat部署
1.单体架构
bash
[root@Nginx conf.d]# cd /usr/local/nginx/conf/conf.d/
[root@Nginx conf.d]# vim vhosts.conf
server {
listen 80;
server_name app.timinglee.org;
location ~* \.jsp$ {
proxy_pass http://172.25.254.10:8080;
}
}
[root@RS1 ~]# cp test.jsp /usr/local/tomcat/webapps/ROOT/
[root@RS1 ~]# scp test.jsp root@172.25.254.20:/usr/local/tomcat/webapps/ROOT/
[root@Nginx conf.d]# nginx -s reload
#在windows中设定app.timinglee.org的解析
#在浏览器中访问 app.timinglee.org/test.jsp
2.tomcat负载均衡
bash
[root@Nginx conf.d]# vim vhosts.conf
upstream tomcat {
hash $cookie_JSESSIONID;
server 172.25.254.10:8080;
server 172.25.254.20:8080;
}
server {
listen 80;
server_name app.timinglee.org;
location ~* \.jsp$ {
proxy_pass http://tomcat;
}
}
[root@Nginx conf.d]# nginx -s reload
#在windows浏览器中访问 app.timinglee.org/test.jsp;
#在windows的另外一个浏览器中访问 app.timinglee.org/test.jsp;
tomcat+memcache
实现session会话零丢失,交叉存储
1.tomcat加载模块
bash
[root@RS1 ~]# unzip jar.zip
[root@RS1 ~]# cd jar/
[root@RS1 jar]# cp * /usr/local/tomcat/lib
[root@RS1 jar]# scp * root@172.25.254.20:/usr/local/tomcat/lib/
2.安装memcache
bash
[root@RS1 jar]# dnf install memcached -y
[root@RS2 ~]# dnf install memcached -y
[root@RS1 ~]# vim /etc/sysconfig/memcached
[root@RS2 ~]# vim /etc/sysconfig/memcached
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="64"
OPTIONS="-l 0.0.0.0,::1"
# 重启+验证
[root@rs1 jar]# systemctl restart memcached.service
[root@RS1+2 ~]# netstat -antluple | grep memcached
tcp 0 0 0.0.0.0:11211 0.0.0.0:* LISTEN 988 142615 35756/memcached
tcp6 0 0 ::1:11211 :::* LISTEN 988 142616 35756/memcached
3.配置tomcat
bash
[root@RS1 ]# vim /usr/local/tomcat/conf/context.xml
<Context>
<!-- Default set of monitored resources. If one of these changes, the -->
<!-- web application will be reloaded. -->
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<WatchedResource>WEB-INF/tomcat-web.xml</WatchedResource>
<WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>
<!-- Uncomment this to disable session persistence across Tomcat restarts -->
<!--
<Manager pathname="" />
-->
<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
memcachedNodes="n1:172.25.254.10:11211,n2:172.25.254.20:11211"
failoverNodes="n1"
requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"
transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"
/>
</Context>
[root@RS2 ]# vim /usr/local/tomcat/conf/context.xml
<Context>
<!-- Default set of monitored resources. If one of these changes, the -->
<!-- web application will be reloaded. -->
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<WatchedResource>WEB-INF/tomcat-web.xml</WatchedResource>
<WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>
<!-- Uncomment this to disable session persistence across Tomcat restarts -->
<!--
<Manager pathname="" />
-->
<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
memcachedNodes="n1:172.25.254.10:11211,n2:172.25.254.20:11211"
failoverNodes="n2"
requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"
transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"
/>
</Context>
[root@RS1 ~]# systemctl restart tomcat.service
[root@RS2 ~]# systemctl restart tomcat.service
#在windows浏览器中访问 app.timinglee.org/test.jsp;
[root@rs1 jar]# systemctl restart tomcat.service
[root@rs1 jar]# systemctl stop tomcat.service
[root@rs1 jar]# systemctl restart tomcat.service
# 写入数据,提交观察观察