JDK及IDE在Mac OS系统中的安装

• JDK 下载与安装
• JDK 配置
• Intellij IDEA安装
• Intellij IDEA 配置JDK

JDK 下载与安装

这个简单，几乎不会出问题，我用的Oracle14，官网下载，如果觉得官网太慢了，也可以通过百度网盘 下载，密码: tabt，安装过程没有任何困难，照着指示走就行。
通过指令

java -version

检查java安装是否成功，成功Terminal会输出

java version "14.0.1" 2020-04-14
Java(TM) SE Runtime Environment (build 14.0.1+7)
Java HotSpot(TM) 64-Bit Server VM (build 14.0.1+7, mixed mode, sharing)

或者通过输入指令

/usr/libexec/java_home -V

检查Java Virtual Machine的数量，路径以及当前使用Java路径

Matching Java Virtual Machines (1):#数量14.0.1, x86_64:	"Java SE 14.0.1"	/Library/Java/JavaVirtualMachines/jdk-14.0.1.jdk/Contents/Home#Java版本及路径/Library/Java/JavaVirtualMachines/jdk-14.0.1.jdk/Contents/Home#当前运行Java版本路径

JDK 配置

回到根目录

cd ~/

如果第一次配置环境变量，多出一步，输入如下指令

touch .bash_profile

然后，打开它

open -e .bash_profile

输入下面几行代码

JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.14.1.jdk/Contents/Home
PATH=$JAVA_HOME/bin:$PATH:.
CLASSPATH=$JAVA_HOME/lib/tools.jar:$JAVA_HOME/lib/dt.jar:.
export JAVA_HOME
export PATH
export CLASSPATH

其中，JAVA_HOME指代Java的根路径（JDK的安装路径），此变量在后续运行Intellij IDEA时会被需要；path 让Java命令被系统可以在任何路径下识别，path本就存在不用新建，而且是编辑添加而不是覆盖，否则其他有些指令会找不到；classpath是加载类（class）的路径，用于加载时Java对其的识别。保存关闭窗口。
特别注意，版本不同，这些Path会有稍许不同。
P.S. 也可以通过

vim ~/.bash_profile

指令去添加路径
终端输入用于激活bash：

source .bash_profile

最后检验Java是否配置成功：

java -version

或者

echo $JAVA_HOME

会返回之前输入的路径

/Library/Java/JavaVirtualMachines/jdk1.14.0.1.jdk/Contents/Home

对于安装成功的版本，输入java, Terminal会输出

Usage: java [options] <mainclass> [args...](to execute a class)or  java [options] -jar <jarfile> [args...](to execute a jar file)or  java [options] -m <module>[/<mainclass>] [args...]java [options] --module <module>[/<mainclass>] [args...](to execute the main class in a module)or  java [options] <sourcefile> [args](to execute a single source-file program)Arguments following the main class, source file, -jar <jarfile>,-m or --module <module>/<mainclass> are passed as the arguments tomain class.where options include:-cp <class search path of directories and zip/jar files>-classpath <class search path of directories and zip/jar files>--class-path <class search path of directories and zip/jar files>A : separated list of directories, JAR archives,and ZIP archives to search for class files.-p <module path>--module-path <module path>...A : separated list of directories, each directoryis a directory of modules.--upgrade-module-path <module path>...A : separated list of directories, each directoryis a directory of modules that replace upgradeablemodules in the runtime image--add-modules <module name>[,<module name>...]root modules to resolve in addition to the initial module.<module name> can also be ALL-DEFAULT, ALL-SYSTEM,ALL-MODULE-PATH.--list-moduleslist observable modules and exit-d <module name>--describe-module <module name>describe a module and exit--dry-run     create VM and load main class but do not execute main method.The --dry-run option may be useful for validating thecommand-line options such as the module system configuration.--validate-modulesvalidate all modules and exitThe --validate-modules option may be useful for findingconflicts and other errors with modules on the module path.-D<name>=<value>set a system property-verbose:[class|module|gc|jni]enable verbose output for the given subsystem-version      print product version to the error stream and exit--version     print product version to the output stream and exit-showversion  print product version to the error stream and continue--show-versionprint product version to the output stream and continue--show-module-resolutionshow module resolution output during startup-? -h -helpprint this help message to the error stream--help        print this help message to the output stream-X            print help on extra options to the error stream--help-extra  print help on extra options to the output stream-ea[:<packagename>...|:<classname>]-enableassertions[:<packagename>...|:<classname>]enable assertions with specified granularity-da[:<packagename>...|:<classname>]-disableassertions[:<packagename>...|:<classname>]disable assertions with specified granularity-esa | -enablesystemassertionsenable system assertions-dsa | -disablesystemassertionsdisable system assertions-agentlib:<libname>[=<options>]load native agent library <libname>, e.g. -agentlib:jdwpsee also -agentlib:jdwp=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 imageHiDPI scaled images are automatically supported and usedif available. The unscaled image filename, e.g. image.ext,should always be passed as the argument to the -splash option.The most appropriate scaled image provided will be picked upautomatically.See the SplashScreen API documentation for more information@argument filesone or more argument files containing options-disable-@filesprevent further argument file expansion--enable-previewallow classes to depend on preview features of this release
To specify an argument for a long option, you can use --<name>=<value> or
--<name> <value>.

输入javac，输出端会输出：

Usage: javac <options> <source files>
where possible options include:@<filename>                  Read options and filenames from file-Akey[=value]                Options to pass to annotation processors--add-modules <module>(,<module>)*Root modules to resolve in addition to the initial modules, or all moduleson the module path if <module> is ALL-MODULE-PATH.--boot-class-path <path>, -bootclasspath <path>Override location of bootstrap class files--class-path <path>, -classpath <path>, -cp <path>Specify where to find user class files and annotation processors-d <directory>               Specify where to place generated class files-deprecationOutput source locations where deprecated APIs are used--enable-previewEnable preview language features. To be used in conjunction with either -source or --release.-encoding <encoding>         Specify character encoding used by source files-endorseddirs <dirs>         Override location of endorsed standards path-extdirs <dirs>              Override location of installed extensions-g                           Generate all debugging info-g:{lines,vars,source}       Generate only some debugging info-g:none                      Generate no debugging info-h <directory>Specify where to place generated native header files--help, -help, -?            Print this help message--help-extra, -X             Print help on extra options-implicit:{none,class}Specify whether or not to generate class files for implicitly referenced files-J<flag>                     Pass <flag> directly to the runtime system--limit-modules <module>(,<module>)*Limit the universe of observable modules--module <module>(,<module>)*, -m <module>(,<module>)*Compile only the specified module(s), check timestamps--module-path <path>, -p <path>Specify where to find application modules--module-source-path <module-source-path>Specify where to find input source files for multiple modules--module-version <version>Specify version of modules that are being compiled-nowarn                      Generate no warnings-parametersGenerate metadata for reflection on method parameters-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--processor-module-path <path>Specify a module path where to find annotation processors--processor-path <path>, -processorpath <path>Specify where to find annotation processors-profile <profile>Check that API used is available in the specified profile--release <release>Compile for the specified Java SE release. Supported releases: 7, 8, 9, 10, 11, 12, 13, 14-s <directory>               Specify where to place generated source files--source <release>, -source <release>Provide source compatibility with the specified Java SE release. Supported releases: 7, 8, 9, 10, 11, 12, 13, 14--source-path <path>, -sourcepath <path>Specify where to find input source files--system <jdk>|none          Override location of system modules--target <release>, -target <release>Generate class files suitable for the specified Java SE release. Supported releases: 7, 8, 9, 10, 11, 12, 13, 14--upgrade-module-path <path>Override location of upgradeable modules-verbose                     Output messages about what the compiler is doing--version, -version          Version information-Werror                      Terminate compilation if warnings occur

Intellij IDEA安装

推荐官网直接下载，community版本是免费开源版本，但是相对功能没有ultimate齐全，在官网下载JetBrains的软件真的有点难受，网站经常登陆不上去，我把2020.2.3 ultimate 版本的下载放在了我的百度网盘，密码是df9w。同样安装按着教程走就对了，千万别用破解版，作为学生，用edu邮箱账户可以免费获得该版本的license，破解版会修改你电脑的hosts，而JB公司对很多破解版本的应对措施越来越有效，很可能你破解了以后会导致正常版本无法使用，而破解版本在几天后也失效。

Intellij IDEA 配置JDK

打开IDEA，新建一个Program

界面如上

如上图点击左上角File>Project Structure

如上图，点击Platform Settings > SDKs > 中间 +号 Add SDK > JDK home path与之前JDK 时设置的Path是一致的，而且应该该IDEA可以直接自动识别出来，然后给该path命名，最后使用该SDK，Apply就可以了。
最后看看能否运行成功，代码如下：

package com.company;public class Main {public static void main(String[] args) {// write your code hereSystem.out.println("Hello World");}
}

control + R 运行，成功的话会在对话框输出

谢谢！