1. 下载jdk

2. 解压jdk，部署jdk

$ tar zxvf jdk-7u71-linux-x64.tar.gz

$ sudo mkdir /usr/lib/jvm

$ sudo tar zxvf jdk-7u71-linux-x64.tar.gz -C /usr/lib/jvm

$ cd /usr/lib/jvm

$ sudo mv jdk1.7.0_71 java

3.添加环境变量

$ sudo vim ~/.bashrc

加入如下内容

export JAVA_HOME=/usr/lib/jvm/ jdk1.7.0_71

export JRE_HOME=${JAVA_HOME}/jre  

export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib  

export PATH=${JAVA_HOME}/bin:$PATH 

4.配置默认JDK版本

sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/java/bin/java 300  

sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java/bin/javac 300  

sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/java/bin/jar 300   

sudo update-alternatives --install /usr/bin/javah javah /usr/lib/jvm/java/bin/javah 300   

sudo update-alternatives --install /usr/bin/javap javap /usr/lib/jvm/java/bin/javap 300   

如未修改jdk路径为java

sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.7.0_71/bin/java 300  

sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0_71/bin/javac 300  

sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/jdk1.7.0_71/bin/jar 300   

sudo update-alternatives --install /usr/bin/javah javah /usr/lib/jvm/jdk1.7.0_71/bin/javah 300   

sudo update-alternatives --install /usr/bin/javap javap /usr/lib/jvm/jdk1.7.0_71/bin/javap 300 

然后执行

sudo update-alternatives --config java

若是初次安装 JDK， 将提示

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

无需配置。

若是非初次安装，将有不同版本的 JDK 选项。

5.测试

$ java -version

java version "1.7.0_21"

Java(TM) SE Runtime Environment (build 1.7.0_21-b11)

Java HotSpot(TM) Server VM (build 23.21-b01, mixed mode)