Java8更新Java11, 修复使java11环境生效

原因:jenkins安装新版本时发现不支持java8了, 需要手动删除旧的8更新到11, 再配置环境变量.
报错:jenkins: invalid Java version: openjdk version "1.8.0_312"

1.先卸载旧的java8

dnf remove java

2.安装装版本java11

yum install -y fontconfig java-11-openjdk java-11-openjdk-devel.x86_64 

3.修复环境变量

#查看当前java环境,如果是java-1.8.0-openjdk-1.8.0.312.b07-1.el8_4.x86_64是错误的,需要删掉重建
ls -l $(which java) 
ls -lr /usr/bin/java
ls -lrt /etc/alternatives/java
rm /etc/alternatives/java
ln -s /usr/lib/jvm/java-11-openjdk-11.0.13.0.8-1.el8_4.x86_64/bin/java /etc/alternatives/java
ll /etc/alternatives/java

#修复环境变量
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-11.0.13.0.8-1.el8_4.x86_64
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/jre/lib/tools.jar:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$PATH
source /etc/profile

4.重启jenkins发现正常启动了

systemctl restart jenkins.service