每次都要卸载系统跟随的openjdk然后装orcle的jdk实在烦人，所以
编写一个脚本执行就省心了，只要将下面的bash脚本和你所在下载的
jdk-7u79-linux-x64.tar.gz包放在同一个文件夹即可。
别忘记，给脚本执行权限
#chmod +x shellname.sh
#../shellname.sh
#!/bin/bash
#shell script to install jdk
# 1. remove openjdk if exists.
for i in $(rpm -qa | grep openjdk | grep -v grep)
do
echo "Deleting rpm -> "$i
rpm -e --nodeps $i
done
if [[ ! -z $(rpm -qa | grep jdk | grep -v grep) ]];
then
echo "-->Failed to remove the defult Jdk."
else
# 2.tar and install JDK(jdk-7u79-linux-x64.tar.gz)
tar -zxvf jdk-7u79-linux-x64.tar.gz
mkdir /usr/java
mv ./jdk1.7.0_79 /usr/java/jdk1.7.0_79
rm -rf ./jdk1.7.0_79
# 3. config /etc/profile
echo "export JAVA_HOME=/usr/java/jdk1.7.0_79" >>/etc/profile
echo -e ‘export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar‘>>/etc/profile
echo -e ‘export PATH=$PATH:$JAVA_HOME/bin‘>>/etc/profile
source /etc/profile
fi