1. 下载 JDK

wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup- cookie" https://download.oracle.com/otn/java/jdk/8u221-b11/230deb18db3e4014bb8e3e8324f81b43/jdk-8u221-linux-x64.tar.gz
提示错误: -bash: wget: command not found
yum -y install wget

2. 安装

1. 创建安装目录

   mkdir /usr/local/java/

2. 解压至安装目录

   tar -zxvf jdk-8u221-linux-x64.tar.gz -C /usr/local/java/

3. 设置环境变量

1. 打开文件

   > vim /etc/profile  
   > 提示错误:  -bash: vim: command not found
   > yum -y install vim*
   > :q 退出vim :q! 直接退出不保存 :wq 保存并退出 :wq! (在可以转换权限的情况下)强制保存并退出

2. 在末尾添加

   export JAVA_HOME=/usr/local/java/jdk1.8.0_221
   export JRE_HOME=${JAVA_HOME}/jre
   export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
   export PATH=${JAVA_HOME}/bin:$PATH

3. 使环境变量生效

   > source /etc/profile

   # 4. 添加软链接

   > ln -s /usr/local/java/jdk1.8.0_221/bin/java /usr/bin/java

   # 5. 检查

   > java -version
   > ![image](https://yqfile.alicdn.com/5945316b8083e9f9a630dc5e7cb11fb21cbc5b2b.png)