Flask Installation Guide: A powerful tool for Python Web development

Teach you step by step how to install Flask: a powerful tool for Python Web development

Introduction:
Flask is a simple and efficient Python Web development framework, which provides a flexible way to build web applications. This article will introduce how to install Flask and provide specific code examples.

1. Install Python
First, we need to install Python. Flask is developed based on Python, so Python must be installed first. The latest version of Python can be downloaded and installed from the official website (https://www.python.org/).

2. Install a virtual environment
In order to isolate project dependencies, it is recommended to create a virtual environment before installing Flask. A virtual environment can prevent dependencies between different projects from interfering with each other.

1. Open the command line tool and enter the folder where you want to create a virtual environment.

2. Run the following command to create a virtual environment:

   python3 -m venv myenv

   This command will create a virtual environment named myenv in the current directory.

3. Run the following command to activate the virtual environment:

   source myenv/bin/activate

   After activating the virtual environment, (myenv) will be displayed in front of the command line to indicate that you have entered the virtual environment.

3. Install Flask
In a virtual environment, installing Flask is very simple.

1. Make sure the virtual environment is activated.

2. Run the following command to install Flask:

   pip install Flask

   After the installation is completed, Flask will be successfully installed in the virtual environment.

4. Create a Flask application
Now that we have successfully installed Flask, we will create a simple Flask application.

1. Create a file named app.py in the directory of the virtual environment.

2. Open app.py and add the following code:

   from flask import Flask
   
   # 创建Flask应用
   app = Flask(__name__)
   
   # 定义路由和视图函数
   @app.route('/')
   def hello():
    return 'Hello Flask!'
   
   # 运行应用
   if __name__ == '__main__':
    app.run()

   This code creates a Flask application named app and defines a view function hello for the root route/ (). When accessing the root route, "Hello Flask!" will be returned.

3. Save and close the app.py file.

5. Run the Flask application
After the Flask application is created, you can run it to see the effect.

1. In the command line, make sure the virtual environment is activated.
2. Enter the directory where app.py is located.

3. Run the following command to start the Flask application:

   python app.py

   After the application is started, the command line will display the running address (usually http://127.0.0.1:5000/).

4. Open the browser, enter the running address, and you will see the words "Hello Flask!".

6. Summary
Through this article, we learned how to install Flask and create a simple Flask application. As a powerful tool for Python Web development, Flask provides rich functions and flexible programming methods, which greatly simplifies the development process of Web applications. I hope this article will be helpful to everyone and help you better use the Flask framework in Python Web development.

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