进入系统环境变量
sudo gedit /etc/profile


#  set java environment
export JAVA_HOME=/home/liwenjie/Software/jdk1.8.0_131
export JRE_HOME=${JAVA_HOME}/jre  
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib  
export PATH=${JAVA_HOME}/bin:$PATH

ubuntu环境变量之jdk