1. 下载：
http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
2. 解压安装：
sudo tar zxvf ./jdk-7u45-linux-x64.tar.gz -C /usr/lib/jvm cd /usr/lib/jvm sudo mv jdk1.7.0_45/ java-7-sun
3. 环境变量：
export JAVA_HOME=/usr/lib/jvm/java-7-sun 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：
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/java-7-sun/bin/java 300 sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java-7-sun/bin/javac 300 sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/java-7-sun/bin/jar 300 sudo update-alternatives --install /usr/bin/javah javah /usr/lib/jvm/java-7-sun/bin/javah 300 sudo update-alternatives --install /usr/bin/javap javap /usr/lib/jvm/java-7-sun/bin/javap 300
sudo update-alternatives --config java
参考：http://blog.csdn.net/snowdream86/article/details/6677450
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原文：http://www.cnblogs.com/sunshy/p/3675240.html