• 解压缩

tar -zxvf jdk-8u221-linux-x64.tar.gz

• 移动安装包

mv jdk1.8.0_221/ /usr/local/

• 重命名

mv /usr/local/jdk1.8.0_221/ /usr/local/java

• 设置所有者

chown -R root:root /usr/local/java/

• 配置系统环境变量

vi /etc/environment

添加如下语句

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"
export JAVA_HOME=/usr/local/java
export JRE_HOME=/usr/local/java/jre
export CLASSPATH=$CLASSPATH:$JAVA_HOME/lib:$JAVA_HOME/jre/lib

• 配置用户环境变量

vi /etc/profile

添加如下语句

if [ "$PS1" ]; then
  if [ "$BASH" ] && [ "$BASH" != "/bin/sh" ]; then
    # The file bash.bashrc already sets the default PS1.
    # PS1='\h:\w\$ '
    if [ -f /etc/bash.bashrc ]; then
      . /etc/bash.bashrc
    fi
  else
    if [ "`id -u`" -eq 0 ]; then
      PS1='# '
    else
      PS1='$ '
    fi
  fi
fi

export JAVA_HOME=/usr/local/java
export JRE_HOME=/usr/local/java/jre
export CLASSPATH=$CLASSPATH:$JAVA_HOME/lib:$JAVA_HOME/jre/lib
export PATH=$JAVA_HOME/bin:$JAVA_HOME/jre/bin:$PATH:$HOME/bin 

if [ -d /etc/profile.d ]; then
  for i in /etc/profile.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi 

• 使用户环境变量生效

source /etc/profile

• 测试是否安装成功

java -version

• 为其他用户更新用户环境变量

su ubuntu
 source /etc/profile