ubuntu 下安装jdk

ubuntu 下安装jdk

1、在官网上下载JDK（选择相应的 .gz包下载 ）
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

由于在官网上下载比较慢，如果远程服务器上有，也可以在远程服务器上下载已经下载好的JDK
命令如下

sudo scp 账号@远程地址:/home/jdk-8u101-linux-x64.tar.gz /home/mdl/xk然后输入远程地址的账号的密码，即可下载

2、创建目录

sudo mkdir /usr/lib/jvm

3、将jdk文件解压缩

sudo tar -zxvf jdk-7u60-linux-x64.gz -C /usr/lib/jvm

4、修改环境变量

$sudo gedit ~/.bashrc 或者sudo vi ~/.bashrc

5、文件的末尾追加下面内容

#set oracle jdk environmentexport JAVA_HOME=/usr/lib/jvm/jdk1.7.0_60  ## 这里要注意目录要换成自己解压的jdk 目录export JRE_HOME=${JAVA_HOME}/jre  export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib  export PATH=${JAVA_HOME}/bin:$PATH 

6、使环境变量马上生效

source ~/.bashrc

7、设置系统默认jdk 版本

sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.7.0_60/bin/java 300  sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0_60/bin/javac 300  sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/jdk1.7.0_60/bin/jar 300   sudo update-alternatives --install /usr/bin/javah javah /usr/lib/jvm/jdk1.7.0_60/bin/javah 300   sudo update-alternatives --install /usr/bin/javap javap /usr/lib/jvm/jdk1.7.0_60/bin/javap 300   

然后执行:

sudo update-alternatives --config java

若是初次安装jdk,会有下面的提示

 There is only one alternative in link group java (providing /usr/bin/java):     /usr/lib/jvm/jdk1.7.0_60/bin/java

否则,选择合适的jdk

8、测试jdk

java -versionjava version "1.7.0_60"  Java(TM) SE Runtime Environment (build 1.7.0_60-b19)  Java HotSpot(TM) 64-Bit Server VM (build 24.60-b09, mixed mode)

参考http://www.cnblogs.com/a2211009/p/4265225.html