Oracle JDK

tar zxf jdk-8u20-linux-x64.tar.gz -C /opt
update-alternatives --install /usr/bin/java java /opt/jdk1.8.0_20/bin/java 300
update-alternatives --install /usr/bin/javah javah /opt/jdk1.8.0_20/bin/javah 300
update-alternatives --install /usr/bin/javap javap /opt/jdk1.8.0_20/bin/javap 300
update-alternatives --install /usr/bin/javac javac /opt/jdk1.8.0_20/bin/javac 300
update-alternatives --install /usr/bin/jar jar /opt/jdk1.8.0_20/bin/jar 300
update-alternatives --set java /opt/jdk1.8.0_20/bin/java
update-alternatives --set javah /opt/jdk1.8.0_20/bin/javah
update-alternatives --set javap /opt/jdk1.8.0_20/bin/javap
update-alternatives --set javac /opt/jdk1.8.0_20/bin/javac
update-alternatives --set jar /opt/jdk1.8.0_20/bin/jar

配置环境变量

这个步骤可选！

vim /etc/profile

export JAVA_HOME=/opt/jdk1.8.0_20
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=$PATH:${JAVA_HOME}/bin:${JRE_HOME}/bin

source /etc/profile