CentOS版本：CentOS Linux release 7.5.1804 (Core)
JDK版本：jdk-8u181-linux-x64
1、先去java官网下载jdk（注意32位还是64位）
网址：http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
2、执行 rpm -ivh jdk-8u181-linux-x64.rpm 命令安装jdk
[root@localhost home]# rpm -ivh jdk-8u181-linux-x64.rpm
警告：jdk-8u181-linux-x64.rpm: 头V3 RSA/SHA256 Signature, 密钥 ID ec551f03: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:jdk1.8-2000:1.8.0_181-fcs ################################# [100%]
Unpacking JAR files...
tools.jar...
plugin.jar...
javaws.jar...
deploy.jar...
rt.jar...
jsse.jar...
charsets.jar...
localedata.jar...3、执行 java -version 命令检查是否安装成功
[root@localhost home]# java -version
java version "1.8.0_181"
Java(TM) SE Runtime Environment (build 1.8.0_181-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode)