jdk1.8 下载地址： http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
1. 安装JDK1.8
下载后使用root用户登录:
mkdir /usr/java将jdk-8u25-linux-x64.tar.gz 移动到/usr/java目录下，解压：
tar -zxvf jdk-8u25-linux-x64.tar.gz2. 配置环境变量
vi /etc/profile
在最后添加以下代码：
# Java Environment Configuration
export JAVA_HOME=/usr/java/jdk1.8.0_25
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib.toos.jar
export PATH=$PATH:$JAVA_HOME/bin
3. 更新 alternatives，选择JDK版本
首先安装 java alternative ---jdk
然后配置JDK：
[root@localhost ~]# update-alternatives --config java
There is 1 program that provides 'java'.
Selection Command
-----------------------------------------------
*+ 1 /usr/java/jdk1.8.0/bin/java
Enter to keep the current selection[+], or type selection number: 1
[root@localhost ~]# java -version
java version "1.8.0_25"
Java(TM) SE Runtime Environment (build 1.8.0_25-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode)OK.安装完毕。下一步准备安装hadoop咯 ~
转播
