centos安装jdk

1. 查看是否已安装jdk

[root@izwz972rwz9s5l70pvt1djz ~]# java -version
openjdk version "1.8.0_161"
OpenJDK Runtime Environment (build 1.8.0_161-b14)
OpenJDK 64-Bit Server VM (build 25.161-b14, mixed mode)

2. 如果有则进行卸载

[root@izwz972rwz9s5l70pvt1djz ~]# yum remove *java*

3. 在http://www.oracle.com/technetwork/java/javase/downloads/上下载相应版本的rpm包，执行下面的命令安装

[root@izwz972rwz9s5l70pvt1djz ~]# rpm -ivh jdk-8u161-linux-x64.rpm 

4. 测试是否安装完成

[root@izwz972rwz9s5l70pvt1djz ~]# java -version
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, mixed mode)
[root@izwz972rwz9s5l70pvt1djz ~]# javac -version
javac 1.8.0_161

5. 如果测试失败则配置环境变量后在测试，默认安装路径为/user/java，配置环境变量

[root@izwz972rwz9s5l70pvt1djz ~]# vim /etc/profile

在/etc/profile文件的最下面添加
export JAVA_HOME=/usr/java/jdk1.8.0_161
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

执行source /etc/profile 使修改生效。