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.批改名称为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的地位即可。（/usr/local/src/jdk1.8）
6.让环境变量失效
source /etc/profile
7.验证jdk是否装置胜利
java -version