1.打开官网，下载Java安装文件。
jdk-7u15-linux-x64.tar.gz
2.打开终端，根据个人习惯创建目录。
sudo mkdir /usr/local/development
3.将下载的文件移动到这个文件夹下并解压缩。使用以下命令：
sudo mv jdk-7u15-linux-x64.tar.gz /usr/local/development
sudo tar -zxvf jdk-7u15-linux-x64.tar.gz
4.修改环境变量
sudo gedit /etc/environment源文件的内容是这样的：PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games '修改为：PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:$ { JAVA _ HOME }/bin ' JAVA _ HOME=/usr/local/development/JDK 1 .7 .0 _ 15JRE _ HOME=$ { JAVA _ HOME }/JRE
CLASSPATH=.${JAVA_HOME}/lib:${JRE_HOME}/lib'
5.重新加载bashrc
source ~/.bashrc
6.配置默认JDKsudo更新-替代项-安装/usr/bin/Java Java/usr/local/development/JDK 1。7 .0 _ 15/bin/Java 300
sudo update-alternatives --install /usr/bin/javac javac /usr/local/development/jdk1.7.0_15/bin/javac 300sudo update-alternatives --install /usr/bin/javap javap /usr/local/development/jdk1.7.0_15/bin/javap 300
sudo update-alternatives --install /usr/bin/javadoc javadoc /usr/local/development/jdk1.7.0_15/bin/javadoc 300
7.测试：
The java version is shown as follows: Allen @ Arlen -top 2:~ $ Java-version Java version' 1.7.0 _ 15' Java (TM) SE runtime environment (Build 1.7.0 _ 15-B03) Java hotspot (TM) 64-bit server VM (build 23.7-b01, mixed mode.
