flask - jcr

flask - jcr

Flask是一个基于Python开发并且依赖jinja2模板和Werkzeug WSGI服务的一个微型框架,对于Werkzeug本质是Socket服务端,其用于接收http请求并对请求进行预处理,然后触发Flask框架,开发人员基于Flask框架提供的功能对请求进行相应的处理,并返回给用户,如果要返回给用户复杂的内容时,需要借助jinja2模板来实现对模板的处理,即:将模板和数据进行渲染,将渲染后的字符串返回给用户浏览器。

“微”(micro) 并不表示你需要把整个 Web 应用塞进单个 Python 文件(虽然确实可以 ),也不意味着 Flask 在功能上有所欠缺。微框架中的“微”意味着 Flask 旨在保持核心简单而易于扩展。Flask 不会替你做出太多决策——比如使用何种数据库。而那些 Flask 所选择的——比如使用何种模板引擎——则很容易替换。除此之外的一切都由可由你掌握。如此,Flask 可以与您珠联璧合。

默认情况下,Flask 不包含数据库抽象层、表单验证,或是其它任何已有多种库可以胜任的功能。然而,Flask 支持用扩展来给应用添加这些功能,如同是 Flask 本身实现的一样。众多的扩展提供了数据库集成、表单验证、上传处理、各种各样的开放认证技术等功能。Flask 也许是“微小”的,但它已准备好在需求繁杂的生产环境中投入使用。

 

一般情况下使用pycharm可直接创建flask项目

也可使用命令   pip install Flask

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 from werkzeug.wrappers import Request, Response
 4 
 5 @Request.application
 6 def hello(request):
 7     return Response("Hello World!")
 8 
 9 if __name__ == "__main__":
10     from werkzeug.serving import run_simple
11     run_simple("localhost", 4000, hello)
werkzeug
1 from flask import Flask
2 app = Flask(__name__)
3  
4 @app.route("/")
5 def hello():
6     return "Hello World!"
7  
8 if __name__ == "__main__":
9     app.run()
first piapia

一、路由系统

  • @app.route("/user/<username>")
  • @app.route("/post/<int:post_id>")
  • @app.route("/post/<float:post_id>")
  • @app.route("/post/<path:path>")
  • @app.route("/login", methods=["GET", "POST"])
# 常用路由系统有以上五种,所有的路由系统都是基于一下对应关系来处理

DEFAULT_CONVERTERS = {
    "default":          UnicodeConverter,
    "string":           UnicodeConverter,
    "any":              AnyConverter,
    "path":             PathConverter,
    "int":              IntegerConverter,
    "float":            FloatConverter,
    "uuid":             UUIDConverter,
}
# 对于Flask默认不支持直接写正则表达式的路由,不过可以通过自定义来实现
通过运行如下代码:

from flask import Flask
from pprint import pprint

if __name__ == "__main__":
    app = Flask(__name__)
    pprint(app.url_map.converters)
可以获取Flask默认支持的转换器:

{"any": <class "werkzeug.routing.AnyConverter">,
 "default": <class "werkzeug.routing.UnicodeConverter">,
 "float": <class "werkzeug.routing.FloatConverter">,
 "int": <class "werkzeug.routing.IntegerConverter">,
 "path": <class "werkzeug.routing.PathConverter">,
 "string": <class "werkzeug.routing.UnicodeConverter">}



那如何创建一个新的路由解析转化器呢?
在Flask的app.py里有个简单的例子,这个例子是创建了一个list类型的路由转换器:

from werkzeug.routing import BaseConverter           
                                                     
class ListConverter(BaseConverter):                  
    def to_python(self, value):                      
        return value.split(",")                      
    def to_url(self, values):                        
        return ",".join(BaseConverter.to_url(value)  
                        for value in values)         
                                                     
app = Flask(__name__)                                
app.url_map.converters["list"] = ListConverter


那么我们可以容易创建一个正则解析器,因为之前的转换器最终也是转换成正则的,只需要将获取的值设置为regex属性就可以使用了:

from flask import Flask
from werkzeug.routing import BaseConverter
class RegexConverter(BaseConverter):
    def __init__(self, map, *args):
        self.map = map
        self.regex = args[0]

app = Flask(__name__)
app.url_map.converters["regex"] = RegexConverter

@app.route("/view/<regex("[a-zA-Z0-9]+"):uuid>/")
def view(uuid):
    """
    url: /view/1010000000125259/
    result: view uuid:1010000000125259
    """
    return "view uuid: %s" % (uuid)

@app.route("/<regex(".*"):url>")
def not_found(url):
    """
    url: /hello
    result: not found: "hello"
    """
    return "not found: "%s"" % (url)

if __name__ == "__main__":
    app.run()
正则

二、模板

1、模板的使用

Flask使用的是Jinja2模板,所以其语法和Django无差别

2、自定义模板方法

Flask中自定义模板方法的方式和Bottle相似,创建一个函数并通过参数的形式传入render_template

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <h1>自定义函数</h1>
    {{ww()|safe}}

</body>
</html>
xxx.html
xxx.py

三、公共组件

 1 # 对于Http请求,Flask会讲请求信息封装在request中(werkzeug.wrappers.BaseRequest),提供的如下常用方法和字段以供使用
 2 request.method
 3 request.args
 4 request.form
 5 request.values
 6 request.files
 7 request.cookies
 8 request.headers
 9 request.path
10 request.full_path
11 request.script_root
12 request.url
13 request.base_url
14 request.url_root
15 request.host_url
16 request.host
请求
 1 @app.route("/login", methods=["POST", "GET"])
 2 def login():
 3     error = None
 4     if request.method == "POST":
 5         if valid_login(request.form["username"],
 6                        request.form["password"]):
 7             return log_the_user_in(request.form["username"])
 8         else:
 9             error = "Invalid username/password"
10     # the code below is executed if the request method
11     # was GET or the credentials were invalid
12     return render_template("login.html", error=error)
表单处理
1 from flask import request
2 from werkzeug import secure_filename
3 
4 @app.route("/upload", methods=["GET", "POST"])
5 def upload_file():
6     if request.method == "POST":
7         f = request.files["the_file"]
8         f.save("/var/www/uploads/" + secure_filename(f.filename))
9     ...
文件上传
 1 from flask import request
 2 
 3 @app.route("/setcookie/")
 4 def index():
 5     username = request.cookies.get("username")
 6     # use cookies.get(key) instead of cookies[key] to not get a
 7     # KeyError if the cookie is missing.
 8 
 9 
10 
11 
12 from flask import make_response
13 
14 @app.route("/getcookie")
15 def index():
16     resp = make_response(render_template(...))
17     resp.set_cookie("username", "the username")
18     return resp
cookie

-----------------------------------------------------------------------------------------------------

 1 # 当用户请求被开发人员的逻辑处理完成之后,会将结果发送给用户浏览器,那么就需要对请求做出相应的响应。
 2 a.字符串
 3 
 4 @app.route("/index/", methods=["GET", "POST"])
 5 def index():
 6     return "index"
 7 b.模板引擎
 8 
 9 from flask import Flask,render_template,request
10 app = Flask(__name__)
11  
12 @app.route("/index/", methods=["GET", "POST"])
13 def index():
14     return render_template("index.html")
15  
16 app.run()
17 c.重定向
18 
19 #!/usr/bin/env python
20 # -*- coding:utf-8 -*-
21 from flask import Flask, redirect, url_for
22 app = Flask(__name__)
23  
24 @app.route("/index/", methods=["GET", "POST"])
25 def index():
26     # return redirect("/login/")
27     return redirect(url_for("login"))
28  
29 @app.route("/login/", methods=["GET", "POST"])
30 def login():
31     return "LOGIN"
32  
33 app.run()
34 d.错误页面
35 
36 from flask import Flask, abort, render_template
37 app = Flask(__name__)
38 
39 @app.route("/e1/", methods=["GET", "POST"])
40 def index():
41     abort(404, "Nothing")
42 app.run()
43 
44 
45 from flask import Flask, abort, render_template
46 app = Flask(__name__)
47  
48 @app.route("/index/", methods=["GET", "POST"])
49 def index():
50     return "OK"
51  
52 @app.errorhandler(404)
53 def page_not_found(error):
54     return render_template("page_not_found.html"), 404
55  
56 app.run()
57 e.设置相应信息
58 
59 使用make_response可以对相应的内容进行操作
60 
61 from flask import Flask, abort, render_template,make_response
62 app = Flask(__name__)
63  
64 @app.route("/index/", methods=["GET", "POST"])
65 def index():
66     response = make_response(render_template("index.html"))
67     # response是flask.wrappers.Response类型
68     # response.delete_cookie
69     # response.set_cookie
70     # response.headers["X-Something"] = "A value"
71     return response
72  
73 app.run()
响应
 1 # 除请求对象之外,还有一个 session 对象。它允许你在不同请求间存储特定用户的信息。它是在 Cookies 的基础上实现的,并且对 Cookies 进行密钥签名要使用会话,你需要设置一个密钥。
 2 
 3 # 设置:session["username"] = "xxx"
 4 
 5 # 删除:session.pop("username", None)
 6 
 7 
 8 
 9 from flask import Flask, session, redirect, url_for, escape, request
10  
11 app = Flask(__name__)
12  
13 @app.route("/")
14 def index():
15     if "username" in session:
16         return "Logged in as %s" % escape(session["username"])
17     return "You are not logged in"
18  
19 @app.route("/login", methods=["GET", "POST"])
20 def login():
21     if request.method == "POST":
22         session["username"] = request.form["username"]
23         return redirect(url_for("index"))
24     return """
25         <form action="" method="post">
26             <p><input type=text name=username>
27             <p><input type=submit value=Login>
28         </form>
29     """
30  
31 @app.route("/logout")
32 def logout():
33     # remove the username from the session if it"s there
34     session.pop("username", None)
35     return redirect(url_for("index"))
36  
37 # set the secret key.  keep this really secret:
38 app.secret_key = "A0Zr98j/3yX R~XHH!jmN]LWX/,?RT"
session
 1 # message是一个基于Session实现的用于保存数据的集合,其特点是:使用一次就删除
 2 
 3 # index.html
 4 
 5 <!DOCTYPE html>
 6 <html>
 7 <head lang="en">
 8     <meta charset="UTF-8">
 9     <title></title>
10 </head>
11 <body>
12     {% with messages = get_flashed_messages() %}
13         {% if messages %}
14         <ul class=flashes>
15             {% for message in messages %}
16             <li>{{ message }}</li>
17             {% endfor %}
18         </ul>
19         {% endif %}
20     {% endwith %}
21 </body>
22 </html>
23 
24 
25 
26 #view.py
27 from flask import Flask, flash, redirect, render_template, request
28  
29 app = Flask(__name__)
30 app.secret_key = "some_secret"
31  
32 @app.route("/")
33 def index1():
34     return render_template("index.html")
35  
36 @app.route("/set")
37 def index2():
38     v = request.args.get("p")
39     flash(v)
40     return "ok"
41  
42 if __name__ == "__main__":
43     app.run()
message
 1 from flask import Flask, flash, redirect, render_template, request
 2  
 3 app = Flask(__name__)
 4 app.secret_key = "some_secret"
 5  
 6 @app.route("/")
 7 def index1():
 8     return render_template("index.html")
 9  
10 @app.route("/set")
11 def index2():
12     v = request.args.get("p")
13     flash(v)
14     return "ok"
15  
16 class MiddleWare:
17     def __init__(self,wsgi_app):
18         self.wsgi_app = wsgi_app
19  
20     def __call__(self, *args, **kwargs):
21  
22         return self.wsgi_app(*args, **kwargs)
23  
24 if __name__ == "__main__":
25     app.wsgi_app = MiddleWare(app.wsgi_app)
26     app.run(port=9999)
中间件

其他

http://docs.jinkan.org/docs/flask/
http://flask.pocoo.org/