ubuntu 下面安装jdk的简便方法

下载jdk，然后解压，比如解压到当前工作空间hp的jdk1.7目录下面，然后执行下面3个命令就ok了，以后切换jdk也很方便。

sudo update-alternatives --install "/usr/bin/java" "java" "/home/ibm/jdk1.7/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/home/ibm/jdk1.7/bin/javac" 1 
sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/home/ibm/jdk1.7/bin/javaws" 1