1.CentOS中OpenJDK 删除

rpm -qa | grep jdk | xargs rpm -e --nodeps  
rpm -qa | grep java | xargs rpm -e --nodeps  

2.系统中安装Oracle JDK 安装

1.cd /opt
2.mkdir software
3.cd software/
4.mkdir java
5.cd java/
6.wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u131-b11/d54c1d3a095b4ff2b6607d096fa80163/jdk-8u131-linux-x64.tar.gz
7.tar zxvf jdk-8u131-linux-x64.tar.gz
8.设置环境变量
打开 /etc/profile 文件在末尾添加
export JAVA_HOME=/opt/software/java/jdk1.8.0_131
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
9.执行生效
source /etc/profile 
10.验证安装
java -version