去下载 jdk http:/www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html创建 jvm 目录sudo mkdir /usr/lib/jvm解压tar xzvf jdk-8u45-linux-i586.tar.gz移动到 jvm 目录sudo mv jdk1.8.0_45 /usr/lib/jvm配置环境变量sudo gedit /etc/profile在目录 /etc/profil e 在末尾加上：需要 root权限 export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_45 export JRE_HOME=$JAVA_HOME/jre export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib export PATH=$JAVA_HOME/bin:$PATH 或者JAVA_HOME=/usr/java/jdk1.8.0_45PATH=$JAVA_HOME/bin:$PATHCLASSPATH=.:$JAVA_HOME/lib/export JAVA_HOMEexport PATHexport CLASSPATHsudo update-alternatives -install /usr/bin/java java /usr/lib/jvm/jdk1.8.0_45/bin/java 300 sudo update-alternatives -install /usr/bin/java java /usr/lib/jvm/jdk1.8.0_45/bin/java 300 sudo update-alternatives -install /usr/bin/jar jar /usr/lib/jvm/jdk1.8.0_45/bin/jar 300第五步：查看 java 版本号 命令行：