Flask Web开发入门（二）之Flask-Login使用

深藏阁楼爱情的钟 2022-06-01 20:41 272阅读 0赞

[上一章][Link 1]我们介绍了使用Flask开发基本的Web应用，并使用session来进行基本的登录授权验证，接下来我们将使用Flask-Login来进行会话管理，来处理我们的“**登入、登出**”问题

> [Flask-Login][] provides user session management for Flask. It handles the common tasks of logging in, logging out, and remembering your users’ sessions over extended periods of time.

**It will:**

*  Store the active user’s ID in the session, and let you log them in and out easily.
 *  Let you restrict views to logged-in (or logged-out) users.
 *  Handle the normally-tricky “remember me” functionality.
 *  Help protect your users’ sessions from being stolen by cookie thieves.
 *  Possibly integrate with Flask-Principal or other authorization extensions later on.

**However, it does not:**

*  Impose a particular database or other storage method on you. You are entirely in charge of how the user is loaded.
 *  Restrict you to using usernames and passwords, OpenIDs, or any other method of authenticating.
 *  Handle permissions beyond “logged in or not.”
 *  Handle user registration or account recovery.

还是上一章的Web应用，

*  首先，通过LoginManager.init\_app创建我们的应用，并通过login\_view指定默认登录页，如果用户没有登录，则自动跳转到登录页:

app = Flask(__name__)
    login_manager = LoginManager()
    login_manager.init_app(app)
    
    login_manager.login_view = 'login'
    login_manager.login_message = 'please login!'
    login_manager.session_protection = 'strong'
    logger = flask_logger.get_logger(__name__)

> flask\_logger.get\_logger是我们自定义的日志模块，后续介绍

*  修改路由方法**login**

@app.route('/login', methods=['GET', 'POST'])
    def login():
        if request.method == 'POST':
            logger.debug("login post method")
            username = request.form['username']
            password = request.form['password']
    
            user = flask_db.get_user_engine(username)
            logger.debug('db user id is %s, detail is %s' % (user.username, user))
    
            next_url = request.args.get("next")
            logger.debug('next is %s' % next_url)
    
            if password == 'admin123' and username == user.username:
                # set login user
                user = User()
                user.id = username
                flask_login.login_user(user)
    
                resp = make_response(render_template('index.html', name=username))
                resp.set_cookie('username', username)
                if not is_safe_url(next_url):
                    return abort(400)
                return redirect(next_url or url_for('index'))
            else:
                return abort(401)
    
        logger.debug("login get method")
        return render_template('login.html')

> 注意，用户通过验证之后，使用**login\_user**方法让用户登录，**flask\_db.get\_user\_engine**自定义获取数据库用户方法，后续介绍  
>   
> 当用户请求重定向到登入视图，它的请求字符串中会有一个 next 变量，其值为用户之前访问的页面，因此在我们完成验证之后，我们通过**request.args.get(“next”)**获取到用户之前访问的页面地址，并进行重定向，注意建议对此参数进行安全校验，避免重定向攻击

*  使用**login\_required**装饰器确保首页授权访问

@app.route('/', methods=['GET', 'POST'])
    @app.route('/index', methods=['GET', 'POST'])
    @flask_login.login_required
    def index():
        logger.debug("index page, method is %s" % request.method)
        return render_template('index.html', name=flask_login.current_user.id)

*  这里，稍微修改前端登录页面如下：

<!doctype html> <html lang="zh"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>用户登录</title> <link rel="stylesheet" type="text/css" href="{ { url_for('static', filename='css/styles.css') }}"/> <link rel="shortcut icon" href="{ { url_for('static', filename='images/wd_favicon.ico')}}"/> </head> <body> <div class="htmleaf-container"> <div class="wrapper"> <div class="container"> <h1>Welcome</h1>  <form class="form" method="post" action=""> <input type="text" placeholder="Username" name="username" id="username"> <input type="password" placeholder="Password" name="password" id="password"> <button type="submit" id="login-button">Login</button> </form> </div> <ul class="bg-bubbles"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> </div> </div> <script src="{ { url_for('static', filename='js/jquery-2.1.1.min.js') }} " type="text/javascript"></script> <div style="text-align:center;margin:50px 0; font:normal 14px/24px 'MicroSoft YaHei';color:#000000"> <h1>管理后台</h1> </div> </body> </html>

*  默认首页index.html，使用部分使用[Jinjia][]模板，部分使用[Layui][]

<!DOCTYPE html> <html lang="zh"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>首页</title> <link rel="stylesheet" type="text/css" href="{ { url_for('static', filename='js/layui/css/layui.css') }}"/> <script src="{ { url_for('static', filename='js/jquery-2.1.1.min.js') }}" type="text/javascript"></script> <script src="{ { url_for('static', filename='js/layui/layui.js') }}" type="text/javascript"></script> <link rel="shortcut icon" href="{ { url_for('static', filename='images/favicon.ico')}}"/> </head> <body> <div style="width: 80%; float:left; margin: 10px 5px;font-family: Consolas;font-size: 20px;"> {% if name %} Hello { { name }}! {% else %} Hello World! {% endif %} </div> <div style="float:right; width: 10%;margin: 10px 5px;font-family: Consolas;font-size: 20px;"> <a href="#" onclick="javascript:logout();">logout</a> </div> <table class="layui-table"> <colgroup> <col width="150"> <col width="200"> <col> </colgroup> <thead> <tr> <th>昵称</th> <th>加入时间</th> <th>签名</th> </tr> </thead> <tbody> <tr> <td>贤心</td> <td>2016-11-29</td> <td>layui</td> </tr> <tr> <td>许闲心</td> <td>2016-11-28</td> <td>table</td> </tr> </tbody> </table> <script type="text/javascript"> var logout = function () { window.location.href = '/logout'; } </script> </body> </html>

*  登出路由方法**logout**

@app.route('/logout')
    @flask_login.login_required
    def logout():
        # remove the username from the session if it's there
        logger.debug("logout page")
        flask_login.logout_user()
        return redirect(url_for('login'))

至此，我们完成了使用Flask-Login的登入、登出管理，接下来，我们介绍使用**Request Loader**定制登录

[http://www.pythondoc.com/flask-login/][http_www.pythondoc.com_flask-login]

[http://flask-login.readthedocs.io/en/latest/\#login-example][http_flask-login.readthedocs.io_en_latest_login-example]

**源码参考：**[https://github.com/ypmc/flask-sqlalchemy-web][https_github.com_ypmc_flask-sqlalchemy-web]

[Link 1]: http://blog.csdn.net/kangkanglou/article/details/79006501
[Flask-Login]: http://flask-login.readthedocs.io/en/latest/
[Jinjia]: http://jinja.pocoo.org/
[Layui]: http://www.layui.com/
[http_www.pythondoc.com_flask-login]: http://www.pythondoc.com/flask-login/
[http_flask-login.readthedocs.io_en_latest_login-example]: http://flask-login.readthedocs.io/en/latest/#login-example
[https_github.com_ypmc_flask-sqlalchemy-web]: https://github.com/ypmc/flask-sqlalchemy-web