（Mac）JDK

一、环境准备

1. 检查环境

   liuzd@liuzhendongdeMacBook-Pro ~ % java -version
   The operation couldn’t be completed. Unable to locate a Java Runtime.
   Please visit http://www.java.com for information on installing Java.
   liuzd@liuzhendongdeMacBook-Pro ~ % 
   

2. 如果已经安装了，可以完全卸载后再检查。

   # JRE（java 8 会自动安装 JRE，考虑到切换最好卸载）
   liuzd@liuzhendongdeMacBook-Pro ~ % sudo rm -rf /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
   liuzd@liuzhendongdeMacBook-Pro ~ % sudo rm -fr /Library/PreferencesPanes/JavaControlPanel.prefPane
   # JDK，查看当前版本 ls /Library/Java/JavaVirtualMachines/
   liuzd@liuzhendongdeMacBook-Pro ~ % sudo rm -rf /Library/Java/JavaVirtualMachines/jdk-1.8.jdk
   # 运行环境
   liuzd@liuzhendongdeMacBook-Pro ~ % sudo rm -rf /Library/Application\ Support/Java
   

二、安装

1. 官网下下，点击安装

2. 打开配置文件

   # 创建配置文件
   liuzd@liuzhendongdeMacBook-Pro ~ % touch ~/.bash_profile
   # 打开配置文件并编辑
   liuzd@liuzhendongdeMacBook-Pro ~ % open -a /Applications/Visual\ Studio\ Code.app ~/.bash_profile
   

3. 环境变量配置（多版本切换）

   # >>> java initialize >>>
   # 切换种类
   export JAVA_8_HOME=`/usr/libexec/java_home -v1.8`
   export JAVA_11_HOME=`/usr/libexec/java_home -v11`
   
   CLASSPAHT=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
   PATH=$JAVA_HOME/bin:$PATH:
   # 默认为1.8
   export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-1.8.jdk/Contents/Home
   export CLASSPATH
   export PATH
   
   # 别名切换
   alias jdk8="export JAVA_HOME=$JAVA_8_HOME"
   alias jdk11="export JAVA_HOME=$JAVA_11_HOME"
   # <<< java initialize <<<
   

4. 配置文件操作

   # 配置生效
   liuzd@liuzhendongdeMacBook-Pro ~ % source .bash_profile 
   # 默认设置
   liuzd@liuzhendongdeMacBook-Pro ~ % java -version
   java version "1.8.0_391"
   Java(TM) SE Runtime Environment (build 1.8.0_391-b13)
   Java HotSpot(TM) 64-Bit Server VM (build 25.391-b13, mixed mode)
   # 切换 jdk11
   liuzd@liuzhendongdeMacBook-Pro ~ % jdk11
   liuzd@liuzhendongdeMacBook-Pro ~ % java -version
   java version "11.0.21" 2023-10-17 LTS
   Java(TM) SE Runtime Environment 18.9 (build 11.0.21+9-LTS-193)
   Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.21+9-LTS-193, mixed mode)
   # 切换 jdk8
   liuzd@liuzhendongdeMacBook-Pro ~ % jdk8
   liuzd@liuzhendongdeMacBook-Pro ~ % java -version
   java version "1.8.0_391"
   Java(TM) SE Runtime Environment (build 1.8.0_391-b13)
   Java HotSpot(TM) 64-Bit Server VM (build 25.391-b13, mixed mode)
   

5. 预防配置失效处理

   # 创建并打开配置
   liuzd@liuzhendongdeMacBook-Pro ~ % touch ~/.zshrc
   liuzd@liuzhendongdeMacBook-Pro ~ % open -a /Applications/Visual\ Studio\ Code.app ~/.zshrc
   # 文件内容
   source ~/.bash_profile
   # 配置生效
   liuzd@liuzhendongdeMacBook-Pro ~ % source ~/.zshrc