第一步
java -version
yum list installed | grep [java][jdk]
![在这里插入图片描述](https://img-blog.csdnimg.cn/20200322153912875.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0pJU09PTFVP,size_16,color_FFFFFF,t_70)
yum -y remove java-1.8.0-openjdk* //表时卸载所有openjdk相关文件输入
yum -y remove tzdata-java.noarch //卸载tzdata-java
第二步
yum search java | grep -i --color jdk
![在这里插入图片描述](https://img-blog.csdnimg.cn/20200322154120508.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0pJU09PTFVP,size_16,color_FFFFFF,t_70)
yum install -y java-1.8.0-openjdk java-1.8.0-openjdk-devel
yum install -y java-1.8.0-openjdk*
java -version
![在这里插入图片描述](https://img-blog.csdnimg.cn/20200322154335568.png)
第三步
- 配置环境变量
- JDK默认安装路径/usr/lib/jvm
ls /usr/lib/jvm
![在这里插入图片描述](https://img-blog.csdnimg.cn/20200322154527779.png)
vim /etc/profile
JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.242.b08-0.el7_7.x86_64
PATH=$PATH:$JAVA_HOME/bin
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME CLASSPATH PATH
source /etc/profile
echo $JAVA_HOME
echo $PATH
echo $CLASSPATH
![在这里插入图片描述](https://img-blog.csdnimg.cn/20200322155112565.png)