ubuntu通过压缩包安装JDK

1.解压到一个目录
sudo tar zxvf jdk-7u45-linux-x64.tar.gz  -C /disk1/jdk

2.设置环境变量

编辑  /etc/profile 文件追加
export JAVA_HOME=/disk1/jdk/jdk1.7.0_79 
export CLASSPATH=".:$JAVA_HOME/lib:$CLASSPATH" 
export PATH="$JAVA_HOME/bin:$PATH"

source /etc/profile

3.设置系统默认jdk
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.7.0_60/bin/java 300 
sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0_60/bin/javac 300 
sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/jdk1.7.0_60/bin/jar 300  
sudo update-alternatives --install /usr/bin/javah javah /usr/lib/jvm/jdk1.7.0_60/bin/javah 300  
sudo update-alternatives --install /usr/bin/javap javap /usr/lib/jvm/jdk1.7.0_60/bin/javap 300


sudo update-alternatives --config java