Install Python3
Because CentOS7 originally installed the Python2.7, and can not be deleted, because many system commands are dependent on Python2, such as we often use the Yum tools.
So, we first need to install Python3 separately, we find the Python official website ftp:
https://www.python.org/ftp/python/
Then find the version we want, like Python3.6.5, and then download it with wget:
# wget Https://www.python.org/ftp/python/3.6.5/Python-3.6.5.tgz
Then create a new directory:
# Mkdir/usr/local/python3
Extract the python-3.6.5.tgz that you just downloaded to the directory:
# cd/usr/local/python3
# tar zxvf/root/python-3.6.5.tgz
Then configure, compile, and install:
# CD Python-3.6.5
#./configure--prefix=/usr/local/python3
# make
Install
For ease of use, we create soft links for it:
# ln-s/usr/local/python3/bin/python3/usr/bin/python3
# ln-s/USR/LOCAL/PYTHON3/BIN/PIP3/USR/BIN/PIP3
Installation completed, check:
# Python3--version
Python 3.6.5
# pip3--version
pip 9.0.3 from/usr/local/python3/lib/python3.6/ Site-packages (Python 3.6)
Flask Experiment
Flask is a lightweight WEB framework written in Python (so we spent so much time in front of it to install Python3). It is called a micro-architecture because it uses very simple cores and feature-rich extensions. Although the flask kernel does not have a default database, validation tools, etc., it is extensible by adding ORM, verification tools, file uploads, and open authentication to enable very powerful WEB applications.
Okay, that's actually flask's installation is very simple:
# PIP3 Install flask
After the installation, we write a back-end code app.py, as follows:
#-*-Coding:utf-8-*-from
flask import flask, jsonify, render_template, request
app = Flask (__name__)
@app. Route ("/")
def Index (): Return
render_template (' index.html ')
@app. Route ('/value ', methods=[' POST '))
def cal_value ():
if Request.method = = ' POST ':
a = Request.form.get (' A ', 0, type=int)
B = Request.form.get (' B ', 0, Type=int) return
jsonify (result = a + b)
if __name__== "__main__":
App.run (host = ' 0.0.0.0 ', port = 8080, debug = True)
We know that Flask uses an adorner @app. Route ("/") to define the URL path. Therefore, the app.py has two routing features: one route can be accessed using the HTTP GET method, return an HTML page, and another route can be accessed using the HTTP POST method, returning the result of the addition of two parameters A and B.
Index.html's code is also simple, where JavaScript is written based on JQuery, as follows:
<! DOCTYPE html>
The entire engineering directory structure is as follows:
# tree
.
├──app.py
├──static
│ └──jquery.js
└──templates
└──index.html
2 directories, 3 files
Next, we run the Web back end:
# Python3 app.py
* Running on http://0.0.0.0:8080/(press CTRL + to quit)
* Restarting with stat
* Debugger is active!
* Debugger pin:184-286-467
Open the browser and enter ip:8080 to access:
We enter the parameters A and B in the input box, click on the calculation, you can see the results. Experiment finished ~