环境

centos7操作系统

步骤

1. 查看安装的jdk
   [root@localhost ~]#rpm -qa | grep openjdk
   java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64
   java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64
   java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64
   java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
2. 卸载jdk
   yum -y remove java-*
3. 下载jdk
   wget --no-cookie --no-check-certificate --header "Cookie: oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u171-b11/512cd62ec5174c3487ac17c61aaa89e8/jdk-8u171-linux-x64.tar.gz
   解压: tar -zxvf jdk-8u171-linux-x64.tar.gz
   重命名: mv jdk-8u171-linux-x64.tar.gz jdk1.8
4. 配置环境变量
   vim /etc/profile 在文件的末尾增加:
   export JAVA_HOME=/root/jdk1.8
   export PATH=$JAVA_HOME/bin:$PATH
   export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
   刷新环境变量: source /etc/profile
   测试java: java -version