1.查看CentOS自带的JDK

yum list installed | grep java

2.卸载自带JDK

java -version

yum -y remove java-1.7.0-openjdk*

yum -y remove tzdata-java.noarch

java -version

3.查看yum库中的Java安装包

yum -y list java*

4.安装JDK

yum -y install java-1.8.0-openjdk*

java -version