Under centos7 installation jdk8

1. Download the corresponding jdk uploaded to the server
2. To extract the installation directory

tar -zxvf jdk-8u231-linux-x64.tar.gz

1. Rename & delete archive

rm jdk-8u231-linux-x64.tar.gz 
mv jdk-8u231 jdk1.8

1. Editing environment variable configuration file

vi /etc/profile

1. Add at the end:

# java env setting
export JAVA_HOME=/opt/jdk1.8
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

1. Validate the configuration

source /etc/profile  

1. Verification, the version number appears successful

java -version