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安装 flask

1.首先在官网下载python3.8安装（注意add环境变量）

2. windows    cmd  运行

pip install requests

报错：一大串红 raise ReadTimeoutError(self._pool, None, 'Read timed out.') pip._vendor.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Read timed out.

3.在Windows下：

C:\Users\Administrator\下新建pip文件夹，在创建pip.ini文件，拷贝下面代码进去，保存。

[global] index-url = https://pypi.tuna.tsinghua.edu.cn/simple

4.windows下在cmd中，linux在终端下输入如下命令：

pip --default-timeout=100 install -U pip

5.再次执行就行了 

pip3 install lxml

报错：

WARNING: You are using pip version 19.2.3, however version 19.3.1 is available.

You should consider upgrading via the 'python -m pip install --upgrade pip' command.

6.运行

python -m pip install -U pip

7.再次执行命令

再次报错：

  raise ReadTimeoutError(self._pool, None, "Read timed out.") pip._vendor.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Read timed out.

库网

8.pip install 保存路径/加上下载的文件名 进行安装

或者pip install --index-url https://pypi.tuna.tsinghua.edu.cn/simple/ lxml

ok了

pip install flask或者pip install --index-url https://pypi.tuna.tsinghua.edu.cn/simple/ flask

OK了

>python main.py * Serving Flask app "main" (lazy loading) * Environment: production   WARNING: This is a development server. Do not use it in a production deployment.   Use a production WSGI server instead. * Debug mode: off * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

 --user

windows

Could not install packages due to an EnvironmentError: [WinError 5] 拒绝访问。: 'c:\\program files\\python\\lib\\site-packages\\pip-10.0.1.dist-info\\entry_points.txt'

Consider using the `--user` option or check the permissions.

pip install bs4 --userpip install requests --user

pycharm报错ModuleNotFoundError: No module named 'bs4'

1.    File– Setting

2.    Project:Python – Project Interperter

3.+ =》搜索=》bs4

4.install package

5.install successfully

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