Python 为什么Flask服务器避免打开特定端口？

当我指定一个IP和端口时，没有前面的说明：

if __name__ == '__main__':

因此：

app.run(host="138.165.91.210",port=5017,threaded=True)

它工作，但它挂起一点（它是否挂在无限循环上？）。当我照常做的时候：

if __name__ == '__main__':
    app.run(host="138.165.91.210",port=5017,threaded=True) 

它避免了ip和端口。我的代码怎么了

完整脚本：

import os
from sqlite3 import dbapi2 as sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, \
     render_template, flash


# create our little application :)
app = Flask(__name__)


# Load default config and override config from an environment variable



def connect_db():
    """Connects to the specific database."""
    rv = sqlite3.connect(app.config['DATABASE'])
    rv.row_factory = sqlite3.Row
    return rv


def init_db():
    """Initializes the database."""
    db = get_db()
    with app.open_resource('schema.sql', mode='r') as f:
        db.cursor().executescript(f.read())
    db.commit()


@app.cli.command('initdb')
def initdb_command():
    """Creates the database tables."""
    init_db()
    print('Initialized the database.')


def get_db():
    """Opens a new database connection if there is none yet for the
    current application context.
    """
    if not hasattr(g, 'sqlite_db'):
        g.sqlite_db = connect_db()
    return g.sqlite_db


@app.teardown_appcontext
def close_db(error):
    """Closes the database again at the end of the request."""
    if hasattr(g, 'sqlite_db'):
        g.sqlite_db.close()


@app.route('/')
def show_entries():
    db = get_db()
    cur = db.execute('select title, text from entries order by id desc')
    entries = cur.fetchall()
    return render_template('show_entries.html', entries=entries)


@app.route('/add', methods=['POST'])
def add_entry():
    if not session.get('logged_in'):
        abort(401)
    db = get_db()
    db.execute('insert into entries (title, text) values (?, ?)',
               [request.form['title'], request.form['text']])
    db.commit()
    flash('New entry was successfully posted')
    return redirect(url_for('show_entries'))


@app.route('/login', methods=['GET', 'POST'])
def login():
    error = None
    if request.method == 'POST':
        if request.form['username'] != app.config['USERNAME']:
            error = 'Invalid username'
        elif request.form['password'] != app.config['PASSWORD']:
            error = 'Invalid password'
        else:
            session['logged_in'] = True
            flash('You were logged in')
            return redirect(url_for('show_entries'))
    return render_template('login.html', error=error)


@app.route('/logout')
def logout():
    session.pop('logged_in', None)
    flash('You were logged out')
    return redirect(url_for('show_entries'))

@app.route("/hello")
def hello():
    return "Hello World!"

if __name__ == '__main__':
    app.run(host="138.165.91.210",port=5017,threaded=True) 

编辑：

我正在使用

bash

运行应用程序：

flask --app=flaskr run

您使用的是Flask的未发布版本，因此请记住，情况可能会发生变化

\uuuuu name\uuuu='\uuuuuu main\uuuuu'

仅在直接执行文件时计算为True（即，

python filename.py

）。因为这不是您在这里运行它的方式，所以它将为False，并跳过该块

要解决端口问题，在使用

flask

命令运行应用程序时，需要通过命令行指定选项

python -m flask --app flaskr --host 138.165.91.210 --port 5017 --with-threads

有关更多信息，请检查用法

python -m flask --help

---

为了解决延迟问题，if uuuu name uuu=='uuuu main uuu'：块很重要。没有它，Flask将尝试运行应用程序的两个实例（一个来自

Flask

命令，另一个来自调用

app.run

）.

您如何运行应用程序？请注意，只有在直接运行脚本时，

\uuu name\uuu

==“main”。@dirn from bash:flask--app=flaskrrun@EugeneSoldatov这是什么意思？推荐阅读：