1. 上传jdk7 和 jdk8 包

2. 解压

[root@localhost webapps]# tar -zxvf /package/jdk-7u80-linux-x64.tar.gz 

3. 配置jdk变量

　vi /etc/profile

export JAVA_HOME=/package/jdk1.7.0_80

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

export PATH=$PATH:$JAVA_HOME/bin

4. java -version

5. 给jdk1.7设置序列号

[xxx@localhost home]$ alternatives --install /usr/bin/java java /package/jdk1.7.0_80 3

6. 安装jdk1.8

[xxx@localhost home]$ alternatives --install /usr/bin/java java /package/jdk1.8.0_124 2

7.选择jdk对应的数字--切换jdk版本

[root@localhost ~]# java -version

java version "1.7.0_80"

Java(TM) SE Runtime Environment (build 1.7.0_80-b15)

Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)

[root@localhost ~]# alternatives --config java

There are 3 programs which provide 'java'.

 Selection  Command

-----------------------------------------------

* 1      /package/jdk1.8.0_121/java

  2      /package/jdk1.8.0_121/bin/java

 + 3      /package/jdk1.7.0_80/bin/java

Enter to keep the current selection[+], or type selection number: 2

[root@localhost ~]# java -version

java version "1.8.0_121"

Java(TM) SE Runtime Environment (build 1.8.0_121-b13)

Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)