ubuntu下安装jdk

1.到oracle去下载源码： jdk-8u121-linux-x64.tar.gz  http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

 解压：tar zvxf jdk-8u121-linux-x64.tar.gz

2.sudo mkdir /usr/lib/jvm 创建目录

3.sudo mv jdk1.8.0_20/ /usr/lib/jvm/  将jdk文件移到/usr/lib/jvm目录下

4.设置JDK环境变量

sudo vim ~/.profile 添加以下代码：

export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_121/

export JRE_HOME=/usr/lib/jvm/jdk1.8.0_121/jre

export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH

export PATH=$JAVA_HOME/bin:$PATH