LINUX安装JDK

1.跳转到指定目录（/usr/local/src）

2.上传linux版本的jdk到当前目录（/usr/local/src）

3.解压文件
tar -zxvf jdk-8u51-linux-x64.tar.gz

4.修改名称为jdk1.8

5.配置环境变量

vim /etc/profile

 # /etc/profile
  2
  3 # System wide environment and startup programs, for login setup
  4 # Functions and aliases go in /etc/bashrc
  5
  6 # It's NOT a good idea to change this file unless you know what you
  7 # are doing. It's much better to create a custom.sh shell script in
  8 # /etc/profile.d/ to make custom changes to your environment, as this
  9 # will prevent the need for merging in future updates.
 10
 11 pathmunge () {
 12     case ":${PATH}:" in
 13         *:"$1":*)
 14             ;;
 15         *)
 16             if [ "$2" = "after" ] ; then
 17                 PATH=$PATH:$1
 18             else
 19                 PATH=$1:$PATH
 20             fi
 21     esac
 22 }
 23
 24
 25 if [ -x /usr/bin/id ]; then
 26     if [ -z "$EUID" ]; then
 27         # ksh workaround
 28         EUID=`/usr/bin/id -u`
 29         UID=`/usr/bin/id -ru`
 30     fi
 31     USER="`/usr/bin/id -un`"
 32     LOGNAME=$USER
 33     MAIL="/var/spool/mail/$USER"
 34 fi
 35
 36 # Path manipulation
 37 if [ "$EUID" = "0" ]; then
 38     pathmunge /usr/sbin
 39     pathmunge /usr/local/sbin
 40 else
 41     pathmunge /usr/local/sbin after
 42     pathmunge /usr/sbin after
 43 fi
 44
 45 HOSTNAME=`/usr/bin/hostname 2>/dev/null`
 46 HISTSIZE=1000
 47 if [ "$HISTCONTROL" = "ignorespace" ] ; then
 48     export HISTCONTROL=ignoreboth
 49 else
 50     export HISTCONTROL=ignoredups
 51 fi
 52
 53 export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE HISTCONTROL
 54
 55 # By default, we want umask to get set. This sets it for login shell
 56 # Current threshold for system reserved uid/gids is 200
 57 # You could check uidgid reservation validity in
 58 # /usr/share/doc/setup-*/uidgid file
 59 if [ $UID -gt 199 ] && [ "`/usr/bin/id -gn`" = "`/usr/bin/id -un`" ]; then
 60     umask 002
 61 else
 62     umask 022
 63 fi
 64
 65 for i in /etc/profile.d/*.sh /etc/profile.d/sh.local ; do
 66     if [ -r "$i" ]; then
 67         if [ "${-#*i}" != "$-" ]; then
 68             . "$i"
 69         else
 70             . "$i" >/dev/null
 71         fi
 72     fi
 73 done
 74
 75 unset i
 76 unset -f pathmunge
 77
 78 #设定jdk环境 
 79 export JAVA_HOME=/usr/local/src/jdk1.8
 80 export PATH=$JAVA_HOME/bin:$PATH
 81 export CLASSPATH=.:$JAVA_HOME/lib

若要更改，只需更改79行jdk的位置即可。（/usr/local/src/jdk1.8）
6.让环境变量生效
source /etc/profile
7.验证jdk是否安装成功
java -version