LINUX 常用操作指令---安装与配置JDK环境

一：环境安装

操作系统：Ubuntu 18.04 

JDK版本：JDK1.8

远程工具：SecureCRT 7.3

 云盘地址：JDK1.8，SecureCRT 7.3，

官网下载的JDK请选择如下图版本：

 二：JDK安装

1、使用CRT远程打开服务器

 2、选择JDK要安装的目录，以/usr/local/为例

root@instance-8scsy8qh:~# cd /usr/local/
root@instance-8scsy8qh:/usr/local# mkdir java
root@instance-8scsy8qh:/usr/local# 
root@instance-8scsy8qh:/usr/local# ls
bin  etc  games  include  java  lib  man  sbin  share  src

3、解压并把JDK版本放置到 /usr/local/java/ 下

root@instance-8scsy8qh:~/softwares# tar -zxvf jdk-8u191-linux-x64.tar.gz 
root@instance-8scsy8qh:~/softwares# ls
jdk1.8.0_191  jdk-8u191-linux-x64.tar.gz
root@instance-8scsy8qh:~/softwares# mv jdk1.8.0_191/ /usr/local/java/
root@instance-8scsy8qh:~/softwares# cd /usr/local/java/
root@instance-8scsy8qh:/usr/local/java# ls
jdk1.8.0_191
root@instance-8scsy8qh:/usr/local/java#

说明：解压-移动到指定目录

三：JDK环境变量配置

这时候JDK就已经准备好了，但是环境我们并没有配置，所以还是Ubuntu系统目前是无法识别并找到该JDK的，验证如下：

root@instance-8scsy8qh:/usr/local/java# java -version

Command 'java' not found, but can be installed with:

apt install default-jre            
apt install openjdk-11-jre-headless
apt install openjdk-8-jre-headless 

root@instance-8scsy8qh:/usr/local/java# 

那么接下来就需要跟类似Windows环境下配置JDK一样了

这边以全局变量作为配置内容，即修改 /etc/profile 

root@instance-8scsy8qh:/usr/local/java# vim /etc/profile
# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).

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

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

export JAVA_HOME=/usr/local/java/jdk1.8.0_191
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib:$CLASSPATH
export JAVA_PATH=${JAVA_HOME}/bin:${JRE_HOME}/bin
export PATH=$PATH:${JAVA_PATH}

 检查是否配置成功

root@instance-8scsy8qh:~# java -version
java version "1.8.0_191"
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)
root@instance-8scsy8qh:~# 

到此，该系统中就已经安装好JDK环境了