1、查看已经安装的jdk
rpm -qa|grep jdk
#java-1.8.0-openjdk-headless-1.8.0.65-3.b17.el7.x86_64
#java-1.7.0-openjdk-1.7.0.91-2.6.2.3.el7.x86_64
#java-1.7.0-openjdk-headless-1.7.0.91-2.6.2.3.el7.x86_64
#java-1.8.0-openjdk-1.8.0.65-3.b17.el7.x86_64
2、卸载命令
sudo yum -y remove java-1.8.0-openjdk-headless-1.8.0.65-3.b17.el7.x86_64
3、验证卸载是否成功
java -version
#bash: java: command not found...
4、下载jdk
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
5、解压到安装目录
sudo mkdir /usr/local/java
sudo tar -zxvf jdk-8u161-linux-x64.tar.gz -C /usr/local/java/
6、添加用户环境变量
系统环境变量省略
export JAVA_HOME=/usr/local/java/jdk1.8.0_191
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin
7、验证
source /home/test/.bash_profile
java -version
