一、Centos6.8服务器上部署tomcat8环境
运行java服务器端程序需要tomcat环境，, 最新的版本是Tomcat 10 ，不过是alpha版，我这里先使用的tomcat8，因为tomcat8目前是一个很稳定的版本。Apache Tomcat 8支持Java EE 7规范，包括Java Servlet 3.1、JSP 2.3、Java统一表达式语言EL 3.0等。tomcat8官网下载地址： Apache Tomcat® - Apache Tomcat 8 Software Downloads ，整个安装过程如下：
#下载tomcat解压安装[root@007 ~]# cd /usr/local/[root@007 local]# wget https://mirrors.bfsu.edu.cn/apache/tomcat/tomcat-8/v8.5.58/bin/apache-tomcat-8.5.58.tar.gz[root@007 local]# ll | grep tomcat-rw-r--r-- 1 root root 10420837 Sep 11 06:03 apache-tomcat-8.5.58.tar.gz[root@007 local]# tar -zxvf apache-tomcat-8.5.58.tar.gz[root@007 local]# mv apache-tomcat-8.5.58 tomcat8.5[root@007 local]# rm -rf apache-tomcat-8.5.58.tar.gz [root@007 local]# cd tomcat8.5/[root@007 tomcat8.5]# cd bin/[root@007 bin]# pwd/usr/local/tomcat8.5/bin#启动tomcat服务[root@007 bin]# /usr/local/tomcat8.5/bin/startup.sh Using CATALINA_BASE: /usr/local/tomcat8.5Using CATALINA_HOME: /usr/local/tomcat8.5Using CATALINA_TMPDIR: /usr/local/tomcat8.5/tempUsing JRE_HOME: /usrUsing CLASSPATH: /usr/local/tomcat8.5/bin/bootstrap.jar:/usr/local/tomcat8.5/bin/tomcat-juli.jarUsing CATALINA_OPTS: Tomcat started.#查看tomcat进程以及tomcat默认监听的端口8080[root@007 bin]# ps -ef | grep tomcatroot 20300 1 19 10:08 pts/2 00:00:02 /usr/bin/java -Djava.util.logging.config.file=/usr/local/tomcat8.5/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /usr/local/tomcat8.5/bin/bootstrap.jar:/usr/local/tomcat8.5/bin/tomcat-juli.jar -Dcatalina.base=/usr/local/tomcat8.5 -Dcatalina.home=/usr/local/tomcat8.5 -Djava.io.tmpdir=/usr/local/tomcat8.5/temp org.apache.catalina.startup.Bootstrap startroot 20333 19746 0 10:09 pts/2 00:00:00 grep --color tomcat[root@007 bin]# netstat -anp | grep tomcat[root@007 bin]# netstat -anp | grep 8080tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN 20300/java 此时在浏览器中访问服务器端的8080端口，即可正常请求（防火墙未阻止的情况下）。在页面上看到我安装的版本是Apache Tomcat/8.5.58， 怎么有一个Tomcat 8.5.0 版本呢。原来Tomcat 9绑定到Java EE8了。Java EE 8延了。Tomcat 8.0.x挺稳定的，很多用户不想加大量新功能影响稳定性。所以出来了一个8.5版本，让想用新技术的用户可以用8.5版。先这样，后期还是有必要换成tomcat9甚至是10版本。
二、Centos6.8下升级jdk1.7环境至jdk1.8
不知道以前什么时候部署过java，很早前服务器也运行过需要java环境的jenkins服务，今天一看上面的java版本是1.7，版本过低，于是升级到1.8。过程如下：
[root@007 ~]# java -version java version "1.7.0_261"OpenJDK Runtime Environment (rhel-2.6.22.1.el6_10-x86_64 u261-b02)OpenJDK 64-Bit Server VM (build 24.261-b02, mixed mode)[root@007 alternatives]# yum list installed |grep javagraphviz-java.x86_64 2.26.0-10.el6 @base java-1.7.0-openjdk.x86_64 1:1.7.0.261-2.6.22.1.el6_10 @updates tzdata-java.noarch 2020a-1.el6 @updates [root@007 alternatives]# yum -y install java-1.8.0-openjdk*....-------------------------------------------------------------------------------------------------------------Total 5.7 MB/s | 218 MB 00:38 Running rpm_check_debugRunning Transaction TestTransaction Test SucceededRunning Transaction Installing : 1:java-1.8.0-openjdk-headless-debug-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-debug-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-devel-debug-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-headless-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-demo-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-devel-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-src-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-demo-debug-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-src-debug-1.8.0.265.b01-0.el6_10.x86_64 Installing : 1:java-1.8.0-openjdk-javadoc-1.8.0.265.b01-0.el6_10.noarch Installing : 1:java-1.8.0-openjdk-javadoc-debug-1.8.0.265.b01-0.el6_10.noarch Verifying : 1:java-1.8.0-openjdk-devel-debug-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-headless-debug-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-demo-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-javadoc-debug-1.8.0.265.b01-0.el6_10.noarch Verifying : 1:java-1.8.0-openjdk-devel-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-src-debug-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-src-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-headless-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-debug-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-javadoc-1.8.0.265.b01-0.el6_10.noarch Verifying : 1:java-1.8.0-openjdk-demo-debug-1.8.0.265.b01-0.el6_10.x86_64 Verifying : 1:java-1.8.0-openjdk-1.8.0.265.b01-0.el6_10.x86_64 Installed: java-1.8.0-openjdk.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-debug.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-demo.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-demo-debug.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-devel.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-devel-debug.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-headless.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-headless-debug.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-javadoc.noarch 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-javadoc-debug.noarch 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-src.x86_64 1:1.8.0.265.b01-0.el6_10 java-1.8.0-openjdk-src-debug.x86_64 1:1.8.0.265.b01-0.el6_10 Complete![root@007 alternatives]# java -versionopenjdk version "1.8.0_265"OpenJDK Runtime Environment (build 1.8.0_265-b01)OpenJDK 64-Bit Server VM (build 25.265-b01, mixed mode)[root@007 alternatives]# 三、tomcat服务器配置用户名和密码登录的403问题
tomcat服务器搭建好之后，默认未开启管理功能。点击页面上的Manager App进入后会报错：403 Access Denied，其中重要的信息如下：
#If you have not changed any configuration files, please examine the file conf/tomcat-users.xml in your installation. That file must contain the credentials to let you use this webapp.
#For example, to add the manager-gui role to a user named tomcat with a password of s3cret, add the following to the config file listed above.
<role rolename="manager-gui"/><user username="tomcat" password="s3cret" roles="manager-gui"/>报错中提示需要编辑conf/tomcat-users.xml 添加访问的用户账号和角色，编辑之后重启tomcat服务。不过我在进行这样的处理后，发现前台的界面仍然是报403错误。找了找原因发现其实tomcat早就提醒我们了，在上面的403报错界面中还有一句提示：
#By default the Manager is only accessible from a browser running on the same machine as Tomcat. If you wish to modify this restriction, you'll need to edit the Manager's context.xml file.
即默认tomcat是只允许本机访问，而不允许远程访问。所以需要修改tomcat8.5/webapps/manager/META-INF/context.xml 文件。将其中的allow这行修改为下方内容（其实就是增加了一个通用IP地址的规则，即允许所有IP地址）
allow="127/./d+/./d+/./d+|::1|0:0:0:0:0:0:0:1|/d+/./d+/./d+/./d+" />然后重启tomcat服务器，进入管理界面就会提示输入账号密码，此时即已成功。
