1）下载jdk： http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

2）放置到/usr/local/software/java 目录下，并解压  tar-xzv -f jdk*.gz 

3）配置环境变量

vim /etc/profile

追加如下内容并保存：

export JAVA_HOME=/usr/local/software/java/jdk1.8.0_162
export JRE_HOME=/usr/local/software/java/jdk1.8.0_162/jre
export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin

4）将java命令添加到bin

5）将javac命令添加到bin

6）选择jdk版本；

[root@localhost jdk1.8.0_162]# update-alternatives --install /usr/bin/java java /usr/local/software/java/jdk1.8.0_162/ 300
[root@localhost jdk1.8.0_162]# update-alternatives --install /usr/bin/javac javac /usr/local/software/java/jdk1.8.0_162/bin/javac 300
[root@localhost jdk1.8.0_162]# update-alternatives --config java共有 3 个程序提供“java”。选择    命令
-----------------------------------------------
*+ 1           /usr/lib/jvm/jre-1.7.0-openjdk/bin/java2           /usr/lib/jvm/jre-1.6.0-openjdk/bin/java3           /usr/local/software/java/jdk1.8.0_162/按 Enter 来保存当前选择[+]，或键入选择号码：3 

7）启用刚才的环境变量；

source /etc/profile 

8）验证： java -version

[root@localhost jdk1.8.0_162]# source /etc/profile
[root@localhost jdk1.8.0_162]# 
[root@localhost jdk1.8.0_162]# java -version
java version "1.8.0_162"
Java(TM) SE Runtime Environment (build 1.8.0_162-b12)
Java HotSpot(TM) Server VM (build 25.162-b12, mixed mode)