为了以后出现不必要的麻烦，一般都采用homebrew进行安装，homebrew是mac的软件包管理器，因此安装python3前先安装homebrew。
一、安装homebrew 我先直接去homebrew官网
复制：
/bin/bash -c "$(curl -fsSL raw.githubusercontent.com/Homebrew/in…)"
结果出现报错：Failed to connect to raw.githubusercontent.com port 443: Connection refused
找了很久终于找到了解决办法：
打开finder ,前往文件夹,输入/private，点击etc，点击设置，显示简介，拉到最下面打开共享与权限，将everyone的权限改为读与写，返回打开etc的子目录，点击hosts，同理将everyone的权限改为读与写，双击编辑
配置加入：199.232.28.133 raw.githubusercontent.com
再将homebrew官网复制的运行到命令行中，没有出现报错，效果如下：
==> This script will install: /usr/local/bin/brew /usr/local/share/doc/homebrew /usr/local/share/man/man1/brew.1 /usr/local/share/zsh/site-functions/_brew /usr/local/etc/bash_completion.d/brew /usr/local/Homebrew ==> The following existing directories will be made writable by user only: /usr/local/share/zsh /usr/local/share/zsh/site-functions
Press RETURN to continue or any other key to abort ==> /usr/bin/sudo /bin/chmod u+rwx /usr/local/share/zsh /usr/local/share/zsh/site-functions ==> /usr/bin/sudo /bin/chmod 755 /usr/local/share/zsh /usr/local/share/zsh/site-functions ==> Downloading and installing Homebrew... remote: Enumerating objects: 43, done. remote: Counting objects: 100% (43/43), done. remote: Compressing objects: 100% (43/43), done. Receiving objects: 9% (13801/139547), 5.39 MiB | 10.00 KiB/s
结果receiving objects又出现安装失败，我真的快崩溃了！！！大家都说多试几次，我试了一下午都没有解决...刚开始以为是分配空间问题，我修改了一下午，结果还是报错，后来再下载开始变的很慢很慢，这也许跟国内国外有关，下载还是出现问题，后来没办法了，找了国内的镜像源才解决问题
zhuanlan.zhihu.com/p/111014448
二、安装python3 查找python3，命令：brew search python3
终于成功了，开心死啦～～～
用命令：which python3 查看一下路径，果然没问题！
