Centos6.5 卸载和安装Java

yum list installed |grep java
#根据列出来的Java信息，删除旧版本的Java信息
yum remove java-1.7
#下载新版本的Java，有可能根据以下的wget的方法不行，我是在Windows上下载的，并且上传上去的
wget http://download.oracle.com/otn-pub/java/jdk/8u92-b14/jdk-8u92-linux-x64.tar.gz tar xvf jdk-8u92-linux-x64.tar.gz
cd jdk1.8.0_92/
#采用alternatives 安装
alternatives --install /usr/bin/java java /opt/jdk1.8.0_92/bin/java 2
alternatives --config java
alternatives --install /usr/bin/jar jar /opt/jdk1.8.0_92/bin/jar 2
alternatives --install /usr/bin/javac javac /opt/jdk1.8.0_92/bin/javac 2
alternatives --set jar /opt/jdk1.8.0_92/bin/jar
alternatives --set javac /opt/jdk1.8.0_92/bin/javac
查看Java的安装版本
java -version
设置环境变量
export JAVA_HOME=/opt/jdk1.8.0_92
export JRE_HOME=/opt/jdk1.8.0_92/jre
export PATH=$PATH:/opt/jdk1.8.0_92/bin:/opt/jdk1.8.0_92/jre/bin

http://tecadmin.net/install-java-8-on-centos-rhel-and-fedora/