通常，我们都是在windows上下载好后，上传到Linux系统的。
1.使用Xftp工具上传到linux系统进行解压
这里的放在/home/用户名
解压包：
# tar -zxvf jdk-7u80-linux-x64.tar.gz
将jdk移动到/usr/local 这个目录下面
# mv jdk1.7.0_80/ /usr/local/
2. 配置环境变量
打开profile文件
执行命令：
# vim /etc/profile
在文件的最后面添加下面配置：
export JAVA_HOME=/usr/local/jdk1.7.0_80
export JRE_HOME =/usr/local/jdk1.7.0_80/jre
export PATH=$PATH:/usr/local/jdk1.7.0_80/bin
export CLASSPATH=./:/usr/local/jdk1.7.0_80/lib:/usr/local/jdk1.7.0_80/jre/lib
或者：
JAVA_HOME=/usr/local/jdk1.7.0_80
JRE_HOME=/usr/local/jdk1.7.0_80/jre
CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
export JAVA_HOME JRE_HOME CLASS_PATH PATH
重新加载文件:
# source /etc/profile
3. 查看java版本是否安装成功
执行命令：
显示版本
# java -version
显示执行参数
# javac
4. JDK版本的选择
【注意】:
（1）、JDK安装在那个用户下，就是给那个用户使用；
（2）、CentOS7 系统默认jdk环境是1.8，在安装的时候就需要，不需要安装最新的版本，但版本不能太低，接近最新版本最好。
以下载最新版为例：
①下载地址为
当前最新版本下载地址：http://www.oracle.com/technetwork/java/javase/downloads/index.html
历史版本下载地址：http://www.oracle.com/technetwork/java/javase/archive-139210.html
②粘贴地址到浏览器地址栏
通过浏览器下载会默认下载到当前登陆用户的下载目录，
例如当前登陆用户是root,那么下载位置为"/root/下载/jdk-8u144-linux-x64.tar.gz".
另外，在服务器或自己运用的系统中如果有网络，JDK版的通过 yum search java 命令查看适合此系统的JDK版本信息：黄色底色的就是适合此系统的。
[jgxy@localhost ~]$ yum search java
java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.6.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.6.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.6.0-openjdk-javadoc.x86_64 : OpenJDK API Documentation
java-1.6.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.7.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.7.0-openjdk-accessibility.x86_64 : OpenJDK accessibility connector
java-1.7.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.7.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.7.0-openjdk-headless.x86_64 : The OpenJDK runtime environment without audio and video support
java-1.7.0-openjdk-javadoc.noarch : OpenJDK API Documentation
java-1.7.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk.i686 : OpenJDK Runtime Environment 8
java-1.8.0-openjdk-accessibility.i686 : OpenJDK accessibility connector
java-1.8.0-openjdk-accessibility.x86_64 : OpenJDK accessibility connector
java-1.8.0-openjdk-accessibility-debug.i686 : OpenJDK 8 accessibility connector for packages with debug on
java-1.8.0-openjdk-accessibility-debug.x86_64 : OpenJDK 8 accessibility connector for packages with debug
: on
java-1.8.0-openjdk-debug.i686 : OpenJDK Runtime Environment 8 with full debug on
java-1.8.0-openjdk-debug.x86_64 : OpenJDK Runtime Environment 8 with full debug on
java-1.8.0-openjdk-demo.i686 : OpenJDK Demos 8
java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos 8
java-1.8.0-openjdk-demo-debug.i686 : OpenJDK Demos 8 with full debug on
java-1.8.0-openjdk-demo-debug.x86_64 : OpenJDK Demos 8 with full debug on
java-1.8.0-openjdk-devel.i686 : OpenJDK Development Environment 8
java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment 8
java-1.8.0-openjdk-devel-debug.i686 : OpenJDK Development Environment 8 with full debug on
java-1.8.0-openjdk-devel-debug.x86_64 : OpenJDK Development Environment 8 with full debug on
java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-headless.i686 : OpenJDK Headless Runtime Environment 8
java-1.8.0-openjdk-headless-debug.i686 : OpenJDK Runtime Environment with full debug on
java-1.8.0-openjdk-headless-debug.x86_64 : OpenJDK Runtime Environment with full debug on
java-1.8.0-openjdk-javadoc.noarch : OpenJDK 8 API documentation
java-1.8.0-openjdk-javadoc-debug.noarch : OpenJDK 8 API documentation for packages with debug on
java-1.8.0-openjdk-javadoc-zip.noarch : OpenJDK 8 API documentation compressed in a single archive
java-1.8.0-openjdk-javadoc-zip-debug.noarch : OpenJDK 8 API documentation compressed in a single archive
: for packages with debug on
java-1.8.0-openjdk-src.i686 : OpenJDK Source Bundle 8
java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle 8
java-1.8.0-openjdk-src-debug.i686 : OpenJDK Source Bundle 8 for packages with debug on
java-1.8.0-openjdk-src-debug.x86_64 : OpenJDK Source Bundle 8 for packages with debug on
java-11-openjdk.i686 : OpenJDK Runtime Environment 11
java-11-openjdk.x86_64 : OpenJDK Runtime Environment 11
java-11-openjdk-debug.i686 : OpenJDK Runtime Environment 11 with full debug on
java-11-openjdk-debug.x86_64 : OpenJDK Runtime Environment 11 with full debug on
java-11-openjdk-demo.i686 : OpenJDK Demos 11
java-11-openjdk-demo.x86_64 : OpenJDK Demos 11
java-11-openjdk-demo-debug.i686 : OpenJDK Demos 11 with full debug on
java-11-openjdk-demo-debug.x86_64 : OpenJDK Demos 11 with full debug on
java-11-openjdk-devel.i686 : OpenJDK Development Environment 11
java-11-openjdk-devel.x86_64 : OpenJDK Development Environment 11
java-11-openjdk-devel-debug.i686 : OpenJDK Development Environment 11 with full debug on
java-11-openjdk-devel-debug.x86_64 : OpenJDK Development Environment 11 with full debug on
java-11-openjdk-headless.i686 : OpenJDK Headless Runtime Environment 11
java-11-openjdk-headless.x86_64 : OpenJDK Headless Runtime Environment 11
java-11-openjdk-headless-debug.i686 : OpenJDK Runtime Environment with full debug on
java-11-openjdk-headless-debug.x86_64 : OpenJDK Runtime Environment with full debug on
java-11-openjdk-javadoc.i686 : OpenJDK 11 API documentation
java-11-openjdk-javadoc.x86_64 : OpenJDK 11 API documentation
java-11-openjdk-javadoc-debug.i686 : OpenJDK 11 API documentation for packages with debug on
java-11-openjdk-javadoc-debug.x86_64 : OpenJDK 11 API documentation for packages with debug on
java-11-openjdk-javadoc-zip.i686 : OpenJDK 11 API documentation compressed in single archive
java-11-openjdk-javadoc-zip.x86_64 : OpenJDK 11 API documentation compressed in a single archive
java-11-openjdk-javadoc-zip-debug.i686 : OpenJDK 11 API documentation compressed in single archive for
: packages with debug on
java-11-openjdk-javadoc-zip-debug.x86_64 : OpenJDK 11 API documentation compressed in a single archive for
: packages with debug on
java-11-openjdk-jmods.i686 : JMods for OpenJDK 11
java-11-openjdk-jmods.x86_64 : JMods for OpenJDK 11
java-11-openjdk-jmods-debug.i686 : JMods for OpenJDK 11 with full debug on
java-11-openjdk-jmods-debug.x86_64 : JMods for OpenJDK 11 with full debug on
java-11-openjdk-src.i686 : OpenJDK Source Bundle 11
java-11-openjdk-src.x86_64 : OpenJDK Source Bundle 11
java-11-openjdk-src-debug.i686 : OpenJDK Source Bundle 11 for packages with debug on
java-11-openjdk-src-debug.x86_64 : OpenJDK Source Bundle 11 for packages with debug on