Debian 手动安装JAVA8

• 首先去官网下载jdk8
  http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

• 创建一个目录/usr/lib/jvm
  sudo mkdir /usr/lib/jvm

• 解压缩安装包至该目录下
  sudo tar zxvf jdk-8u121-linux-x64.tar.gz -C /usr/lib/jvm

• 进入到/usr/lib/jvm目录下
  cd /usr/lib/jvm

• 把解压后的jdk1.8.0_25重命名为jdk-8
  sudo mv jdk1.8.0_121 jdk8

• 添加环境变量
  vim ~/.bashrc

export JAVA_HOME=/usr/lib/jvm/jdk8
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

• 测试是否安装成功
  java -version