contos7 安装 jdk8看这篇就够了（有云盘连接JDK）

环境  centos  + Xshell5

1下载jdk

https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html（

或者我云盘链接：https://pan.baidu.com/s/1dsPvnVzBSgGZiRJeAEo0VA 密码：4uit）

2上传到服务器解压安装包

root@instance-xbnz53gx:/home/java# tar  -zxvf jdk-8u181-linux-x64.tar.gz 

3修改环境变量

root@instance-xbnz53gx:/home/java# vim /etc/profile

扩展只是如果没有vim下面指令安装下

root@instance-xbnz53gx:/home/java# apt-get install vim-gtk

按键  i   进入编辑，把下面的配置复制进去。按键：wq  退出并保存

export JAVA_HOME=/home/java/jdk1.8.0_181
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib:$CLASSPATH
export JAVA_PATH=${JAVA_HOME}/bin:${JRE_HOME}/bin
export PATH=$PATH:${JAVA_PATH}

4 刷新额配置source /etc/profile

root@instance-xbnz53gx:/home/java# source /etc/profile
root@instance-xbnz53gx:/home/java# java
Usage: java [-options] class [args...]
           (to execute a class)
   or  java [-options] -jar jarfile [args...]
           (to execute a jar file)
where options include:
    -d32	  use a 32-bit data model if available
    -d64	  use a 64-bit data model if available
    -server	  to select the "server" VM
                  The default VM is server.

    -cp <class search path of directories and zip/jar files>
    -classpath <class search path of directories and zip/jar files>
                  A : separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
    -D<name>=<value>
                  set a system property
    -verbose:[class|gc|jni]
                  enable verbose output
    -version      print product version and exit
    -version:<value>
                  Warning: this feature is deprecated and will be removed
                  in a future release.
                  require the specified version to run
    -showversion  print product version and continue
    -jre-restrict-search | -no-jre-restrict-search
                  Warning: this feature is deprecated and will be removed
                  in a future release.
                  include/exclude user private JREs in the version search
    -? -help      print this help message
    -X            print help on non-standard options
    -ea[:<packagename>...|:<classname>]
    -enableassertions[:<packagename>...|:<classname>]
                  enable assertions with specified granularity
    -da[:<packagename>...|:<classname>]
    -disableassertions[:<packagename>...|:<classname>]
                  disable assertions with specified granularity
    -esa | -enablesystemassertions
                  enable system assertions
    -dsa | -disablesystemassertions
                  disable system assertions
    -agentlib:<libname>[=<options>]
                  load native agent library <libname>, e.g. -agentlib:hprof
                  see also, -agentlib:jdwp=help and -agentlib:hprof=help
    -agentpath:<pathname>[=<options>]
                  load native agent library by full pathname
    -javaagent:<jarpath>[=<options>]
                  load Java programming language agent, see java.lang.instrument
    -splash:<imagepath>
                  show splash screen with specified image
See http://www.oracle.com/technetwork/java/javase/documentation/index.html for more details.