下载jdk

1. 解压

$ mv /opt
$ mkdir java
$ cd java
$ mv ~/Downloads/jdk-8u144-linux-x64.tar.gz .
$ tar -zxvf jdk-8u144-linux-x64.tar.gz
$ mv jdk-8u144 jdk1.8

2. 设置环境变量

sudo vi /etc/profile

在最后加入如下内容

#set java environment
export JAVA_HOME=/opt/java/jdk1.8
export JRE_HOME=/opt/java/jdk1.8/jre
export CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH

让修改生效

source /etc/profile

3. 验证

java -version
#java version "1.8.0_144"
#Java(TM) SE Runtime Environment (build 1.8.0_144-b01)
#Java HotSpot(TM) 64-Bit Server VM (build 25.144-b01, mixed mode)