Ubuntu14.04安装JDK1.8

环境：
Ubuntu14.04
JDK1.8 到官方网站下载
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
1.将下载的JDK进行解压

 $: tar -xvf ~/Downloads/tar -xvf jdk-8u77-linux-x64.gz

2.创建个目录来存放JDK

 $: sudo mkdir -p /usr/lib/jvm/jdk1.8

3.将JDK下的文件移动到新建的目录下

 $:  sudo mv jdk1.8.0_77/*  /usr/lib/jvm/jdk1.8

4.建立默认JDK的启动

 $: sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.8/bin/java" 1 $: sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.8/bin/javac" 1  $: sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/lib/jvm/jdk1.8/bin/javaws" 1

好了，此时JDK安装完成了

执行下面的代码可以看到当前各种JDK版本和配置：

 $:sudo update-alternatives --config java

5 设置JDK的环境变量

$: sudo su#:vim /etc/environment

添加环境变量
可参见
linux配置java环境变量(详细) - SamZhang - 博客园 http://www.cnblogs.com/samcn/archive/2011/03/16/1986248.html

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/lib/jvm/jdk1.8/bin" CLASSPATH=".:/usr/lib/jvm/jdk1.8/lib" JAVA_HOME="/usr/lib/jvm/jdk1.8"

保存退出
使立马生效

$: source ~/.bashrc

查看是否安装成功

$:java -version