當Linux不啟用圖形介面的時候，我們只能通過命令列來搭建Java環境了。
平臺： CentOS 6.5

1. 下載

不知道後續Oracle公司會不會會不會更新網址，所以以當前時間(2016年7月19日)為例。如果我們有瀏覽器，只需要輸入以下網址：
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
就能開啟Java jdk 的下載頁面了。然後下載即可。
下載的時候需要點選“Accept License Agreement ”，所以用這個命令：

wget http://download.oracle
 
.com/otn-pub/java/jdk/8u91-b14/jdk-8u91-linux-x64.tar.gz

下載下來的檔案只有5K左右，只是一個一個HTML檔案罷了。所以需要輸入以下命令：

wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u91-b14/jdk-8u91-linux-x64.tar.gz

這樣就能下載jdk-8u91-linux-x64.tar.gz 這個壓縮包了。

2. 解壓

建立一個目錄，如我這裡建的目錄是/usr/java/jdk8。

mkdir /usr/java
mkdir /usr/java/jdk8

利用以下命令解壓剛才下載的jdk-8u91-linux-x64.tar.gz壓縮包。進入這個壓縮包所在的目錄，然後輸入以下命令：

tar zxvf jdk-8u91-linux-x64.tar.gz -C /usr/java/jdk8/

解壓之後/usr/java/jdk8/目錄下有一個目錄：jdk1.8.0_91。這就是JDK的安裝目錄。

3. 設定環境變數

修改配置檔案:

vim ~/.bashrc

在檔案中加入：

export JAVA_HOME=/usr/java/jdk8/jdk1.8.0
 
_91/
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

然後輸入命令讓配置檔案生效：

source ~/.bashrc

4. 測試

可以輸入java和javac這兩個命令測試一下。
輸入java輸出結果：

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.

輸入javac 的輸出結果：

Usage: javac <options> <source files>
where possible options include:
  -g                         Generate all debugging info
  -g:none                    Generate no debugging info
  -g:{lines,vars,source}     Generate only some debugging info
  -nowarn                    Generate no warnings
  -verbose                   Output messages about what the compiler is doing
  -deprecation               Output source locations where deprecated APIs are used
  -classpath <path>          Specify where to find user class files and annotation processors
  -cp <path>                 Specify where to find user class files and annotation processors
  -sourcepath <path>         Specify where to find input source files
  -bootclasspath <path>      Override location of bootstrap class files
  -extdirs <dirs>            Override location of installed extensions
  -endorseddirs <dirs>       Override location of endorsed standards path
  -proc:{none,only}          Control whether annotation processing and/or compilation is done.
  -processor <class1>[,<class2>,<class3>...] Names of the annotation processors to run; bypasses default discovery process
  -processorpath <path>      Specify where to find annotation processors
  -parameters                Generate metadata for reflection on method parameters
  -d <directory>             Specify where to place generated class files
  -s <directory>             Specify where to place generated source files
  -h <directory>             Specify where to place generated native header files
  -implicit:{none,class}     Specify whether or not to generate class files for implicitly referenced files
  -encoding <encoding>       Specify character encoding used by source files
  -source <release>          Provide source compatibility with specified release
  -target <release>          Generate class files for specific VM version
  -profile <profile>         Check that API used is available in the specified profile
  -version                   Version information
  -help                      Print a synopsis of standard options
  -Akey[=value]              Options to pass to annotation processors
  -X                         Print a synopsis of nonstandard options
  -J<flag>                   Pass <flag> directly to the runtime system
  -Werror                    Terminate compilation if warnings occur
  @<filename>                Read options and filenames from file</span>

那就說明Java環境已經搭建好了。