添加环境变量

vi /etc/profile

export JAVA_HOME=/usr/java/jdk1.8.0_191
export CLASSPATH=.:%JAVA_HOME%/lib/dt.jar:%JAVA_HOME%/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

export TOMCAT_HOME=/home/tomcat9
export PATH=$PATH:$TOMCAT_HOME/bin


刷新环境变量
source /etc/profile