JDK安装与配置

学的到东西的事情是锻炼，学不到的是磨练。

一、下载JDK

https://www.oracle.com/java/technologies/downloads/#java8-windows
https://www.oracle.com/java/technologies/downloads/#java8-linux

二、Windows安装JDK

1.安装

2.设置环境变量

• 设置JAVA_HOME环境变量

JAVA_HOME=C:\Java\jdk1.8.0_91

• 设置Path环境变量

将C:\Java\jdk1.8.0_91\bin 添加进环境变量中,或者: %JAVA_HOME%\bin

• 设置CLASSPATH环境变量

.;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar

3.测试JAVA

4.安装库源文件和文档库

源文件在JDK中以一个压缩文件src.zip的形式发布，必须将其解压才能访问源代码:

• JAVA_HOME目录下自带有src.zip
• 在JAVA_HOME目录下新建src文件夹
• cd到这个文件夹，执行命令jar -xvf ..\src.zip下载src.zip文件，将其放在src文件夹中

三、Linux安装JDK

1.安装

[root@server ~]# tar xvf jdk-8u411-linux-x64.tar.gz -C /usr/local/

[root@server ~]# cd /usr/local/
[root@server local]# ln -s jdk1.8.0_411 jdk

[root@server local]# ll |grep jdk
lrwxrwxrwx  1 root root   12 Jul 14 08:58 jdk -> jdk1.8.0_411
drwxr-xr-x  8 root root 4096 Jul 14 08:53 jdk1.8.0_411

2.配置环境变量

[root@server local]# vim /etc/profile

export JAVA_HOME=/usr/local/jdk
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

[root@server local]# tail -3 /etc/profile
export JAVA_HOME=/usr/local/jdk
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

[root@server local]# source /etc/profile 

3.校验安装

[root@server local]# java -version
java version "1.8.0_411"
Java(TM) SE Runtime Environment (build 1.8.0_411-b09)
Java HotSpot(TM) 64-Bit Server VM (build 25.411-b09, mixed mode)

[root@server local]# javac
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,full}     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