畅游Python 二十一：Web框架

Tornado 是 FriendFeed 使用的可扩展的非阻塞式 web 服务器及其相关工具的开源版本。这个 Web 框架看起来有些像web.py 或者 Google 的 webapp，不过为了能有效利用非阻塞式服务器环境，这个 Web 框架还包含了一些相关的有用工具和优化。

Tornado 和现在的主流 Web 服务器框架（包括大多数 Python 的框架）有着明显的区别：它是非阻塞式服务器，而且速度相当快。得利于其非阻塞的方式和对 epoll 的运用，Tornado 每秒可以处理数以千计的连接，这意味着对于实时 Web 服务来说，Tornado 是一个理想的 Web 框架。我们开发这个 Web 服务器的主要目的就是为了处理 FriendFeed 的实时功能 ——在 FriendFeed 的应用里每一个活动用户都会保持着一个服务器连接。（关于如何扩容服务器，以处理数以千计的客户端的连接的问题，请参阅 C10K problem。）

下载安装：

pip3 install tornado源码安装
https://pypi.python.org/packages/source/t/tornado/tornado-4.3.tar.gz

Tornado框架使用

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):self.write("Hello, world")application = tornado.web.Application([(r"/index", MainHandler),
])if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

执行过程：

第一步：执行脚本，监听 8888 端口
第二步：浏览器客户端访问 /index --> http://127.0.0.1:8888/index
第三步：服务器接受请求，并交由对应的类处理该请求
第四步：类接受到请求之后，根据请求方式（post / get / delete ...）的不同调用并执行相应的方法
第五步：方法返回值的字符串内容发送浏览器

异步非阻塞代码示例：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.web
from tornado import httpclient
from tornado.web import asynchronous
from tornado import genimport uimodules as md
import uimethods as mtclass MainHandler(tornado.web.RequestHandler):@asynchronous@gen.coroutinedef get(self):print 'start get 'http = httpclient.AsyncHTTPClient()http.fetch("http://127.0.0.1:8008/post/", self.callback)self.write('end')def callback(self, response):print response.bodysettings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/','ui_methods': mt,'ui_modules': md,
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(8009)tornado.ioloop.IOLoop.instance().start()

二、路由系统

路由系统其实就是 url 和类的对应关系，这里不同于其他框架，其他很多框架均是 url 对应函数，Tornado中每个url对应的是一个类。

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):self.write("Hello, world")class StoryHandler(tornado.web.RequestHandler):def get(self, story_id):self.write("You requested the story " + story_id)class BuyHandler(tornado.web.RequestHandler):def get(self):self.write("buy.wupeiqi.com/index")application = tornado.web.Application([(r"/index", MainHandler),(r"/story/([0-9]+)", StoryHandler),
])application.add_handlers('buy.wupeiqi.com$', [(r'/index',BuyHandler),
])if __name__ == "__main__":application.listen(80)tornado.ioloop.IOLoop.instance().start()

Tornado中原生支持二级域名的路由，如：

模板引擎

Tornao中的模板语言和django中类似，模板引擎将模板文件载入内存，然后将数据嵌入其中，最终获取到一个完整的字符串，再将字符串返回给请求者。

Tornado 的模板支持“控制语句”和“表达语句”，控制语句是使用 {% 和 %} 包起来的例如 {% if len(items) > 2 %}。表达语句是使用 {{ 和 }} 包起来的，例如 {{ items[0] }}。

控制语句和对应的 Python 语句的格式基本完全相同。我们支持 if、for、while 和 try，这些语句逻辑结束的位置需要用 {% end %} 做标记。还通过 extends 和 block 语句实现了模板继承。这些在 template 模块的代码文档中有着详细的描述。

注：在使用模板前需要在setting中设置模板路径："template_path" : "tpl"

1、基本使用

app.py代码：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):self.render("index.html", list_info = [11,22,33])application = tornado.web.Application([(r"/index", MainHandler),
])if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

‘index.html’ 代码：

<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><title>老男孩</title><link href="{{static_url("css/common.css")}}" rel="stylesheet" />
</head>
<body><div><ul>{% for item in list_info %}<li>{{item}}</li>{% end %}</ul></div><script src="{{static_url("js/jquery-1.8.2.min.js")}}"></script></body>
</html>

其他方法代码：

在模板中默认提供了一些函数、字段、类以供模板使用：escape: tornado.escape.xhtml_escape 的別名
xhtml_escape: tornado.escape.xhtml_escape 的別名
url_escape: tornado.escape.url_escape 的別名
json_encode: tornado.escape.json_encode 的別名
squeeze: tornado.escape.squeeze 的別名
linkify: tornado.escape.linkify 的別名
datetime: Python 的 datetime 模组
handler: 当前的 RequestHandler 对象
request: handler.request 的別名
current_user: handler.current_user 的別名
locale: handler.locale 的別名
_: handler.locale.translate 的別名
static_url: for handler.static_url 的別名
xsrf_form_html: handler.xsrf_form_html 的別名

2、母版

2.1 layout.html

<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><title>老男孩</title><link href="{{static_url("css/common.css")}}" rel="stylesheet" />{% block CSS %}{% end %}
</head>
<body><div class="pg-header"></div>{% block RenderBody %}{% end %}<script src="{{static_url("js/jquery-1.8.2.min.js")}}"></script>{% block JavaScript %}{% end %}
</body>
</html>

2.2 index.html

{% extends 'layout.html'%}
{% block CSS %}<link href="{{static_url("css/index.css")}}" rel="stylesheet" />
{% end %}{% block RenderBody %}<h1>Index</h1><ul>{%  for item in li %}<li>{{item}}</li>{% end %}</ul>{% end %}{% block JavaScript %}{% end %}

3、导入

3.1 header.html

<div><ul><li>1024</li><li>42区</li></ul>
</div>

3.2 index.html

<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><title>老男孩</title><link href="{{static_url("css/common.css")}}" rel="stylesheet" />
</head>
<body><div class="pg-header">{% include 'header.html' %}</div><script src="{{static_url("js/jquery-1.8.2.min.js")}}"></script></body>
</html>

4、自定义UIMethod以UIModule

4.1 定义

4.1.1 uimethods.py

# uimethods.pydef tab(self):return 'UIMethod'

4.1.2 uimodules.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from tornado.web import UIModule
from tornado import escapeclass custom(UIModule):def render(self, *args, **kwargs):return escape.xhtml_escape('<h1>wupeiqi</h1>')#return escape.xhtml_escape('<h1>wupeiqi</h1>')

4.2 注册

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.web
from tornado.escape import linkify
import uimodules as md
import uimethods as mtclass MainHandler(tornado.web.RequestHandler):def get(self):self.render('index.html')settings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/','ui_methods': mt,'ui_modules': md,
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(8009)tornado.ioloop.IOLoop.instance().start()

4.3 使用

<!DOCTYPE html>
<html>
<head lang="en"><meta charset="UTF-8"><title></title><link href="{{static_url("commons.css")}}" rel="stylesheet" />
</head>
<body><h1>hello</h1>{% module custom(123) %}{{ tab() }}
</body>

四、静态文件

对于静态文件，可以配置静态文件的目录和前段使用时的前缀，并且Tornaodo还支持静态文件缓存。

1. app.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):self.render('home/index.html')settings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/',
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(80)tornado.ioloop.IOLoop.instance().start()

2. index.html

<!DOCTYPE html>
<html>
<head lang="en"><meta charset="UTF-8"><title></title><link href="{{static_url("commons.css")}}" rel="stylesheet" />
</head>
<body><h1>hello</h1>
</body>
</html>

3. 静态文件缓存的实现

def get_content_version(cls, abspath):"""Returns a version string for the resource at the given path.This class method may be overridden by subclasses.  Thedefault implementation is a hash of the file's contents... versionadded:: 3.1"""data = cls.get_content(abspath)hasher = hashlib.md5()if isinstance(data, bytes):hasher.update(data)else:for chunk in data:hasher.update(chunk)return hasher.hexdigest()

五、cookie

Tornado中可以对cookie进行操作，并且还可以对cookie进行签名以放置伪造。

1、基本操作

class MainHandler(tornado.web.RequestHandler):def get(self):if not self.get_cookie("mycookie"):self.set_cookie("mycookie", "myvalue")self.write("Your cookie was not set yet!")else:self.write("Your cookie was set!")

2、加密cookie（签名）

Cookie 很容易被恶意的客户端伪造。加入你想在 cookie 中保存当前登陆用户的 id 之类的信息，你需要对 cookie 作签名以防止伪造。Tornado 通过 set_secure_cookie 和 get_secure_cookie 方法直接支持了这种功能。要使用这些方法，你需要在创建应用时提供一个密钥，名字为 cookie_secret。你可以把它作为一个关键词参数传入应用的设置中：

class MainHandler(tornado.web.RequestHandler):def get(self):if not self.get_secure_cookie("mycookie"):self.set_secure_cookie("mycookie", "myvalue")self.write("Your cookie was not set yet!")else:self.write("Your cookie was set!")application = tornado.web.Application([(r"/", MainHandler),
], cookie_secret="61oETzKXQAGaYdkL5gEmGeJJFuYh7EQnp2XdTP1o/Vo=")

内部算法：

def _create_signature_v1(secret, *parts):hash = hmac.new(utf8(secret), digestmod=hashlib.sha1)for part in parts:hash.update(utf8(part))return utf8(hash.hexdigest())# 加密
def _create_signature_v2(secret, s):hash = hmac.new(utf8(secret), digestmod=hashlib.sha256)hash.update(utf8(s))return utf8(hash.hexdigest())def create_signed_value(secret, name, value, version=None, clock=None,key_version=None):if version is None:version = DEFAULT_SIGNED_VALUE_VERSIONif clock is None:clock = time.timetimestamp = utf8(str(int(clock())))value = base64.b64encode(utf8(value))if version == 1:signature = _create_signature_v1(secret, name, value, timestamp)value = b"|".join([value, timestamp, signature])return valueelif version == 2:# The v2 format consists of a version number and a series of# length-prefixed fields "%d:%s", the last of which is a# signature, all separated by pipes.  All numbers are in# decimal format with no leading zeros.  The signature is an# HMAC-SHA256 of the whole string up to that point, including# the final pipe.## The fields are:# - format version (i.e. 2; no length prefix)# - key version (integer, default is 0)# - timestamp (integer seconds since epoch)# - name (not encoded; assumed to be ~alphanumeric)# - value (base64-encoded)# - signature (hex-encoded; no length prefix)def format_field(s):return utf8("%d:" % len(s)) + utf8(s)to_sign = b"|".join([b"2",format_field(str(key_version or 0)),format_field(timestamp),format_field(name),format_field(value),b''])if isinstance(secret, dict):assert key_version is not None, 'Key version must be set when sign key dict is used'assert version >= 2, 'Version must be at least 2 for key version support'secret = secret[key_version]signature = _create_signature_v2(secret, to_sign)return to_sign + signatureelse:raise ValueError("Unsupported version %d" % version)# 解密
def _decode_signed_value_v1(secret, name, value, max_age_days, clock):parts = utf8(value).split(b"|")if len(parts) != 3:return Nonesignature = _create_signature_v1(secret, name, parts[0], parts[1])if not _time_independent_equals(parts[2], signature):gen_log.warning("Invalid cookie signature %r", value)return Nonetimestamp = int(parts[1])if timestamp < clock() - max_age_days * 86400:gen_log.warning("Expired cookie %r", value)return Noneif timestamp > clock() + 31 * 86400:# _cookie_signature does not hash a delimiter between the# parts of the cookie, so an attacker could transfer trailing# digits from the payload to the timestamp without altering the# signature.  For backwards compatibility, sanity-check timestamp# here instead of modifying _cookie_signature.gen_log.warning("Cookie timestamp in future; possible tampering %r",value)return Noneif parts[1].startswith(b"0"):gen_log.warning("Tampered cookie %r", value)return Nonetry:return base64.b64decode(parts[0])except Exception:return Nonedef _decode_fields_v2(value):def _consume_field(s):length, _, rest = s.partition(b':')n = int(length)field_value = rest[:n]# In python 3, indexing bytes returns small integers; we must# use a slice to get a byte string as in python 2.if rest[n:n + 1] != b'|':raise ValueError("malformed v2 signed value field")rest = rest[n + 1:]return field_value, restrest = value[2:]  # remove version numberkey_version, rest = _consume_field(rest)timestamp, rest = _consume_field(rest)name_field, rest = _consume_field(rest)value_field, passed_sig = _consume_field(rest)return int(key_version), timestamp, name_field, value_field, passed_sigdef _decode_signed_value_v2(secret, name, value, max_age_days, clock):try:key_version, timestamp, name_field, value_field, passed_sig = _decode_fields_v2(value)except ValueError:return Nonesigned_string = value[:-len(passed_sig)]if isinstance(secret, dict):try:secret = secret[key_version]except KeyError:return Noneexpected_sig = _create_signature_v2(secret, signed_string)if not _time_independent_equals(passed_sig, expected_sig):return Noneif name_field != utf8(name):return Nonetimestamp = int(timestamp)if timestamp < clock() - max_age_days * 86400:# The signature has expired.return Nonetry:return base64.b64decode(value_field)except Exception:return Nonedef get_signature_key_version(value):value = utf8(value)version = _get_version(value)if version < 2:return Nonetry:key_version, _, _, _, _ = _decode_fields_v2(value)except ValueError:return Nonereturn key_version

签名Cookie的本质是：

写cookie过程：

将值进行base64加密

对除值以外的内容进行签名，哈希算法（无法逆向解析）

拼接签名 + 加密值

读cookie过程：

读取签名 + 加密值

对签名进行验证

base64解密，获取值内容

注：许多API验证机制和安全cookie的实现机制相同。

基于Cookie实现用户验证代码实例：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):login_user = self.get_secure_cookie("login_user", None)if login_user:self.write(login_user)else:self.redirect('/login')class LoginHandler(tornado.web.RequestHandler):def get(self):self.current_user()self.render('login.html', **{'status': ''})def post(self, *args, **kwargs):username = self.get_argument('name')password = self.get_argument('pwd')if username == 'wupeiqi' and password == '123':self.set_secure_cookie('login_user', '武沛齐')self.redirect('/')else:self.render('login.html', **{'status': '用户名或密码错误'})settings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/','cookie_secret': 'aiuasdhflashjdfoiuashdfiuh'
}application = tornado.web.Application([(r"/index", MainHandler),(r"/login", LoginHandler),
], **settings)if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

基于签名Cookie实现用户验证代码实例：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass BaseHandler(tornado.web.RequestHandler):def get_current_user(self):return self.get_secure_cookie("login_user")class MainHandler(BaseHandler):@tornado.web.authenticateddef get(self):login_user = self.current_userself.write(login_user)class LoginHandler(tornado.web.RequestHandler):def get(self):self.current_user()self.render('login.html', **{'status': ''})def post(self, *args, **kwargs):username = self.get_argument('name')password = self.get_argument('pwd')if username == 'wupeiqi' and password == '123':self.set_secure_cookie('login_user', '武沛齐')self.redirect('/')else:self.render('login.html', **{'status': '用户名或密码错误'})settings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/','cookie_secret': 'aiuasdhflashjdfoiuashdfiuh','login_url': '/login'
}application = tornado.web.Application([(r"/index", MainHandler),(r"/login", LoginHandler),
], **settings)if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

3、JavaScript操作Cookie

由于Cookie保存在浏览器端，所以在浏览器端也可以使用JavaScript来操作Cookie。

/*
设置cookie，指定秒数过期*/
function setCookie(name,value,expires){var temp = [];var current_date = new Date();current_date.setSeconds(current_date.getSeconds() + 5);document.cookie = name + "= "+ value +";expires=" + current_date.toUTCString();
}

对于参数：

domain 指定域名下的cookie
path 域名下指定url中的cookie
secure https使用

注：jQuery中也有指定的插件 jQuery Cookie 专门用于操作cookie，猛击这里

六、CSRF

Tornado中的夸张请求伪造和Django中的相似，跨站伪造请求(Cross-site request forgery)

配置：

settings = {"xsrf_cookies": True,
}
application = tornado.web.Application([(r"/", MainHandler),(r"/login", LoginHandler),
], **settings)

使用普通表单：

<form action="/new_message" method="post">{{ xsrf_form_html() }}<input type="text" name="message"/><input type="submit" value="Post"/>
</form>

使用AJAX：

function getCookie(name) {var r = document.cookie.match("\\b" + name + "=([^;]*)\\b");return r ? r[1] : undefined;
}jQuery.postJSON = function(url, args, callback) {args._xsrf = getCookie("_xsrf");$.ajax({url: url, data: $.param(args), dataType: "text", type: "POST",success: function(response) {callback(eval("(" + response + ")"));}});
};

注：Ajax使用时，本质上就是去获取本地的cookie，携带cookie再来发送请求

七、上传文件

1、Form表单上传

HTML代码：

<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><title>上传文件</title>
</head>
<body><form id="my_form" name="form" action="/index" method="POST"  enctype="multipart/form-data" ><input name="fff" id="my_file"  type="file" /><input type="submit" value="提交"  /></form>
</body>
</html>

Python代码：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):self.render('index.html')def post(self, *args, **kwargs):file_metas = self.request.files["fff"]# print(file_metas)for meta in file_metas:file_name = meta['filename']with open(file_name,'wb') as up:up.write(meta['body'])settings = {'template_path': 'template',
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(8000)tornado.ioloop.IOLoop.instance().start()

2、AJAX上传

HTML - XMLHttpRequest：

<!DOCTYPE html>
<html>
<head lang="en"><meta charset="UTF-8"><title></title>
</head>
<body><input type="file" id="img" /><input type="button" onclick="UploadFile();" /><script>function UploadFile(){var fileObj = document.getElementById("img").files[0];var form = new FormData();form.append("k1", "v1");form.append("fff", fileObj);var xhr = new XMLHttpRequest();xhr.open("post", '/index', true);xhr.send(form);}</script>
</body>
</html>

HTML - jQuery：

<!DOCTYPE html>
<html>
<head lang="en"><meta charset="UTF-8"><title></title>
</head>
<body><input type="file" id="img" /><input type="button" onclick="UploadFile();" /><script>function UploadFile(){var fileObj = $("#img")[0].files[0];var form = new FormData();form.append("k1", "v1");form.append("fff", fileObj);$.ajax({type:'POST',url: '/index',data: form,processData: false,  // tell jQuery not to process the datacontentType: false,  // tell jQuery not to set contentTypesuccess: function(arg){console.log(arg);}})}</script>
</body>
</html>

HTML - iframe：

<!DOCTYPE html>
<html>
<head lang="en"><meta charset="UTF-8"><title></title>
</head>
<body><form id="my_form" name="form" action="/index" method="POST"  enctype="multipart/form-data" ><div id="main"><input name="fff" id="my_file"  type="file" /><input type="button" name="action" value="Upload" onclick="redirect()"/><iframe id='my_iframe' name='my_iframe' src=""  class="hide"></iframe></div></form><script>function redirect(){document.getElementById('my_iframe').onload = Testt;document.getElementById('my_form').target = 'my_iframe';document.getElementById('my_form').submit();}function Testt(ths){var t = $("#my_iframe").contents().find("body").text();console.log(t);}</script>
</body>
</html>

Python代码：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.webclass MainHandler(tornado.web.RequestHandler):def get(self):self.render('index.html')def post(self, *args, **kwargs):file_metas = self.request.files["fff"]# print(file_metas)for meta in file_metas:file_name = meta['filename']with open(file_name,'wb') as up:up.write(meta['body'])settings = {'template_path': 'template',
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(8000)tornado.ioloop.IOLoop.instance().start()

扩展：基于iframe实现Ajax上传示例：

<script type="text/javascript">$(document).ready(function () {$("#formsubmit").click(function () {var iframe = $('<iframe name="postiframe" id="postiframe" style="display: none"></iframe>');$("body").append(iframe);var form = $('#theuploadform');form.attr("action", "/upload.aspx");form.attr("method", "post");form.attr("encoding", "multipart/form-data");form.attr("enctype", "multipart/form-data");form.attr("target", "postiframe");form.attr("file", $('#userfile').val());form.submit();$("#postiframe").load(function () {iframeContents = this.contentWindow.document.body.innerHTML;$("#textarea").html(iframeContents);});return false;});});</script><form id="theuploadform"><input id="userfile" name="userfile" size="50" type="file" /><input id="formsubmit" type="submit" value="Send File" />
</form><div id="textarea">
</div>

py代码：

$('#upload_iframe').load(function(){var iframeContents = this.contentWindow.document.body.innerText;iframeContents = JSON.parse(iframeContents);})

其他：

function bindChangeAvatar1() {$('#avatarImg').change(function () {var file_obj = $(this)[0].files[0];$('#prevViewImg')[0].src = window.URL.createObjectURL(file_obj)})}function bindChangeAvatar2() {$('#avatarImg').change(function () {var file_obj = $(this)[0].files[0];var reader = new FileReader();reader.readAsDataURL(file_obj);reader.onload = function (e) {$('#previewImg')[0].src = this.result;};})}function bindChangeAvatar3() {$('#avatarImg').change(function () {var file_obj = $(this)[0].files[0];var form = new FormData();form.add('img_upload', file_obj);$.ajax({url: '',data: form,processData: false,  // tell jQuery not to process the datacontentType: false,  // tell jQuery not to set contentTypesuccess: function (arg) {}})})}function bindChangeAvatar4() {$('#avatarImg').change(function () {$(this).parent().submit();$('#upload_iframe').load(function () {var iframeContents = this.contentWindow.document.body.innerText;iframeContents = JSON.parse(iframeContents);if (iframeContents.status) {$('#previewImg').attr('src', '/' + iframeContents.data);}})})}

八、验证码

验证码原理在于后台自动创建一张带有随机内容的图片，然后将内容通过img标签输出到页面。

安装图像处理模块：

pip3 install pillow

示例截图：

验证码Demo源码下载：这里

九、异步非阻塞

1、基本使用

装饰器 + Future 从而实现Tornado的异步非阻塞

class AsyncHandler(tornado.web.RequestHandler):@gen.coroutinedef get(self):future = Future()future.add_done_callback(self.doing)yield future# 或# tornado.ioloop.IOLoop.current().add_future(future,self.doing)# yield futuredef doing(self,*args, **kwargs):self.write('async')self.finish()

当发送GET请求时，由于方法被@gen.coroutine装饰且yield 一个 Future对象，那么Tornado会等待，等待用户向future对象中放置数据或者发送信号，如果获取到数据或信号之后，就开始执行doing方法。

异步非阻塞体现在当在Tornaod等待用户向future对象中放置数据时，还可以处理其他请求。

注意：在等待用户向future对象中放置数据或信号时，此连接是不断开的。

2、同步阻塞和异步非阻塞对比

同步阻塞：

class SyncHandler(tornado.web.RequestHandler):def get(self):self.doing()self.write('sync')def doing(self):time.sleep(10)

异步非阻塞：

class AsyncHandler(tornado.web.RequestHandler):@gen.coroutinedef get(self):future = Future()tornado.ioloop.IOLoop.current().add_timeout(time.time() + 5, self.doing)yield futuredef doing(self, *args, **kwargs):self.write('async')self.finish()

3、httpclient类库

Tornado提供了httpclient类库用于发送Http请求，其配合Tornado的异步非阻塞使用。

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.web
from tornado import gen
from tornado import httpclient# 方式一：
class AsyncHandler(tornado.web.RequestHandler):@gen.coroutinedef get(self, *args, **kwargs):print('进入')http = httpclient.AsyncHTTPClient()data = yield http.fetch("http://www.google.com")print('完事',data)self.finish('6666')# 方式二：
# class AsyncHandler(tornado.web.RequestHandler):
#     @gen.coroutine
#     def get(self):
#         print('进入')
#         http = httpclient.AsyncHTTPClient()
#         yield http.fetch("http://www.google.com", self.done)
#
#     def done(self, response):
#         print('完事')
#         self.finish('666')application = tornado.web.Application([(r"/async", AsyncHandler),
])if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

基于异步非阻塞和Tornado-MySQL实现用户登录示例：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
"""
需要先安装支持异步操作Mysql的类库： Tornado-MySQL： https://github.com/PyMySQL/Tornado-MySQL#installationpip3 install Tornado-MySQL"""import tornado.web
from tornado import genimport tornado_mysql
from tornado_mysql import poolsPOOL = pools.Pool(dict(host='127.0.0.1', port=3306, user='root', passwd='123', db='cmdb'),max_idle_connections=1,max_recycle_sec=3)@gen.coroutine
def get_user_by_conn_pool(user):cur = yield POOL.execute("SELECT SLEEP(%s)", (user,))row = cur.fetchone()raise gen.Return(row)@gen.coroutine
def get_user(user):conn = yield tornado_mysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='cmdb',charset='utf8')cur = conn.cursor()# yield cur.execute("SELECT name,email FROM web_models_userprofile where name=%s", (user,))yield cur.execute("select sleep(10)")row = cur.fetchone()cur.close()conn.close()raise gen.Return(row)class LoginHandler(tornado.web.RequestHandler):def get(self, *args, **kwargs):self.render('login.html')@gen.coroutinedef post(self, *args, **kwargs):user = self.get_argument('user')data = yield gen.Task(get_user, user)if data:print(data)self.redirect('http://www.oldboyedu.com')else:self.render('login.html')application = tornado.web.Application([(r"/login", LoginHandler),
])if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

自定义Web组件：

一、Session

1、面向对象基础

面向对象中通过索引的方式访问对象，需要内部实现 __getitem__ 、__delitem__、__setitem__方法

#!/usr/bin/env python
# -*- coding:utf-8 -*-class Foo(object):def __getitem__(self, key):print  '__getitem__',keydef __setitem__(self, key, value):print '__setitem__',key,valuedef __delitem__(self, key):print '__delitem__',keyobj = Foo()
result = obj['k1']
#obj['k2'] = 'wupeiqi'
#del obj['k1']

2、Tornado扩展

Tornado框架中，默认执行Handler的get/post等方法之前默认会执行 initialize方法，所以可以通过自定义的方式使得所有请求在处理前执行操作...

class BaseHandler(tornado.web.RequestHandler):def initialize(self):self.xxoo = "wupeiqi"class MainHandler(BaseHandler):def get(self):print(self.xxoo)self.write('index')class IndexHandler(BaseHandler):def get(self):print(self.xxoo)self.write('index')

3、session

session其实就是定义在服务器端用于保存用户回话的容器，其必须依赖cookie才能实现。

自定义Session：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import config
from hashlib import sha1
import os
import timecreate_session_id = lambda: sha1(bytes('%s%s' % (os.urandom(16), time.time()), encoding='utf-8')).hexdigest()class SessionFactory:@staticmethoddef get_session_obj(handler):obj = Noneif config.SESSION_TYPE == "cache":obj = CacheSession(handler)elif config.SESSION_TYPE == "memcached":obj = MemcachedSession(handler)elif config.SESSION_TYPE == "redis":obj = RedisSession(handler)return objclass CacheSession:session_container = {}session_id = "__sessionId__"def __init__(self, handler):self.handler = handlerclient_random_str = handler.get_cookie(CacheSession.session_id, None)if client_random_str and client_random_str in CacheSession.session_container:self.random_str = client_random_strelse:self.random_str = create_session_id()CacheSession.session_container[self.random_str] = {}expires_time = time.time() + config.SESSION_EXPIREShandler.set_cookie(CacheSession.session_id, self.random_str, expires=expires_time)def __getitem__(self, key):ret = CacheSession.session_container[self.random_str].get(key, None)return retdef __setitem__(self, key, value):CacheSession.session_container[self.random_str][key] = valuedef __delitem__(self, key):if key in CacheSession.session_container[self.random_str]:del CacheSession.session_container[self.random_str][key]class RedisSession:def __init__(self, handler):passclass MemcachedSession:def __init__(self, handler):pass

4、分布式Session

一致性哈希：

#!/usr/bin/env python
#coding:utf-8import sys
import math
from bisect import bisectif sys.version_info >= (2, 5):import hashlibmd5_constructor = hashlib.md5
else:import md5md5_constructor = md5.newclass HashRing(object):"""一致性哈希"""def __init__(self,nodes):'''初始化nodes : 初始化的节点，其中包含节点已经节点对应的权重默认每一个节点有32个虚拟节点对于权重，通过多创建虚拟节点来实现如：nodes = [{'host':'127.0.0.1:8000','weight':1},{'host':'127.0.0.1:8001','weight':2},{'host':'127.0.0.1:8002','weight':1},]'''self.ring = dict()self._sorted_keys = []self.total_weight = 0self.__generate_circle(nodes)def __generate_circle(self,nodes):for node_info in nodes:self.total_weight += node_info.get('weight',1)for node_info in nodes:weight = node_info.get('weight',1)node = node_info.get('host',None)virtual_node_count = math.floor((32*len(nodes)*weight) / self.total_weight)for i in xrange(0,int(virtual_node_count)):key = self.gen_key_thirty_two( '%s-%s' % (node, i) )if self._sorted_keys.__contains__(key):raise Exception('该节点已经存在.')self.ring[key] = nodeself._sorted_keys.append(key)def add_node(self,node):''' 新建节点node : 要添加的节点，格式为：{'host':'127.0.0.1:8002','weight':1}，其中第一个元素表示节点，第二个元素表示该节点的权重。'''node = node.get('host',None)if not node:raise Exception('节点的地址不能为空.')weight = node.get('weight',1)self.total_weight += weightnodes_count = len(self._sorted_keys) + 1virtual_node_count = math.floor((32 * nodes_count * weight) / self.total_weight)for i in xrange(0,int(virtual_node_count)):key = self.gen_key_thirty_two( '%s-%s' % (node, i) )if self._sorted_keys.__contains__(key):raise Exception('该节点已经存在.')self.ring[key] = nodeself._sorted_keys.append(key)def remove_node(self,node):''' 移除节点node : 要移除的节点 '127.0.0.1:8000''''for key,value in self.ring.items():if value == node:del self.ring[key]self._sorted_keys.remove(key)def get_node(self,string_key):'''获取 string_key 所在的节点'''pos = self.get_node_pos(string_key)if pos is None:return Nonereturn self.ring[ self._sorted_keys[pos]].split(':')def get_node_pos(self,string_key):'''获取 string_key 所在的节点的索引'''if not self.ring:return Nonekey = self.gen_key_thirty_two(string_key)nodes = self._sorted_keyspos = bisect(nodes, key)return posdef gen_key_thirty_two(self, key):m = md5_constructor()m.update(key)return long(m.hexdigest(), 16)def gen_key_sixteen(self,key):b_key = self.__hash_digest(key)return self.__hash_val(b_key, lambda x: x)def __hash_val(self, b_key, entry_fn):return (( b_key[entry_fn(3)] << 24)|(b_key[entry_fn(2)] << 16)|(b_key[entry_fn(1)] << 8)| b_key[entry_fn(0)] )def __hash_digest(self, key):m = md5_constructor()m.update(key)return map(ord, m.digest())"""
nodes = [{'host':'127.0.0.1:8000','weight':1},{'host':'127.0.0.1:8001','weight':2},{'host':'127.0.0.1:8002','weight':1},
]ring = HashRing(nodes)
result = ring.get_node('98708798709870987098709879087')
print result"""

session：

from hashlib import sha1
import os, timecreate_session_id = lambda: sha1('%s%s' % (os.urandom(16), time.time())).hexdigest()class Session(object):session_id = "__sessionId__"def __init__(self, request):session_value = request.get_cookie(Session.session_id)if not session_value:self._id = create_session_id()else:self._id = session_valuerequest.set_cookie(Session.session_id, self._id)def __getitem__(self, key):# 根据 self._id ，在一致性哈西中找到其对应的服务器IP# 找到相对应的redis服务器，如： r = redis.StrictRedis(host='localhost', port=6379, db=0)# 使用python redis api 链接# 获取数据，即：# return self._redis.hget(self._id, name)def __setitem__(self, key, value):# 根据 self._id ，在一致性哈西中找到其对应的服务器IP# 使用python redis api 链接# 设置session# self._redis.hset(self._id, name, value)def __delitem__(self, key):# 根据 self._id 找到相对应的redis服务器# 使用python redis api 链接# 删除，即：return self._redis.hdel(self._id, name)

二、表单验证

在Web程序中往往包含大量的表单验证的工作，如：判断输入是否为空，是否符合规则。

HTML：

<!DOCTYPE html>
<html>
<head lang="en"><meta charset="UTF-8"><title></title><link href="{{static_url("commons.css")}}" rel="stylesheet" />
</head>
<body><h1>hello</h1><form action="/index" method="post"><p>hostname: <input type="text" name="host" /> </p><p>ip: <input type="text" name="ip" /> </p><p>port: <input type="text" name="port" /> </p><p>phone: <input type="text" name="phone" /> </p><input type="submit" /></form>
</body>
</html>

Python：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.web
from hashlib import sha1
import os, time
import reclass MainForm(object):def __init__(self):self.host = "(.*)"self.ip = "^(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}$"self.port = '(\d+)'self.phone = '^1[3|4|5|8][0-9]\d{8}$'def check_valid(self, request):form_dict = self.__dict__for key, regular in form_dict.items():post_value = request.get_argument(key)# 让提交的数据 和 定义的正则表达式进行匹配ret = re.match(regular, post_value)print key,ret,post_valueclass MainHandler(tornado.web.RequestHandler):def get(self):self.render('index.html')def post(self, *args, **kwargs):obj = MainForm()result = obj.check_valid(self)self.write('ok')settings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/','cookie_secret': 'aiuasdhflashjdfoiuashdfiuh','login_url': '/login'
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()

由于验证规则可以代码重用，所以可以如此定义：

#!/usr/bin/env python
# -*- coding:utf-8 -*-import tornado.ioloop
import tornado.web
import reclass Field(object):def __init__(self, error_msg_dict, required):self.id_valid = Falseself.value = Noneself.error = Noneself.name = Noneself.error_msg = error_msg_dictself.required = requireddef match(self, name, value):self.name = nameif not self.required:self.id_valid = Trueself.value = valueelse:if not value:if self.error_msg.get('required', None):self.error = self.error_msg['required']else:self.error = "%s is required" % nameelse:ret = re.match(self.REGULAR, value)if ret:self.id_valid = Trueself.value = ret.group()else:if self.error_msg.get('valid', None):self.error = self.error_msg['valid']else:self.error = "%s is invalid" % nameclass IPField(Field):REGULAR = "^(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}$"def __init__(self, error_msg_dict=None, required=True):error_msg = {}  # {'required': 'IP不能为空', 'valid': 'IP格式错误'}if error_msg_dict:error_msg.update(error_msg_dict)super(IPField, self).__init__(error_msg_dict=error_msg, required=required)class IntegerField(Field):REGULAR = "^\d+$"def __init__(self, error_msg_dict=None, required=True):error_msg = {'required': '数字不能为空', 'valid': '数字格式错误'}if error_msg_dict:error_msg.update(error_msg_dict)super(IntegerField, self).__init__(error_msg_dict=error_msg, required=required)class CheckBoxField(Field):def __init__(self, error_msg_dict=None, required=True):error_msg = {}  # {'required': 'IP不能为空', 'valid': 'IP格式错误'}if error_msg_dict:error_msg.update(error_msg_dict)super(CheckBoxField, self).__init__(error_msg_dict=error_msg, required=required)def match(self, name, value):self.name = nameif not self.required:self.id_valid = Trueself.value = valueelse:if not value:if self.error_msg.get('required', None):self.error = self.error_msg['required']else:self.error = "%s is required" % nameelse:if isinstance(name, list):self.id_valid = Trueself.value = valueelse:if self.error_msg.get('valid', None):self.error = self.error_msg['valid']else:self.error = "%s is invalid" % nameclass FileField(Field):REGULAR = "^(\w+\.pdf)|(\w+\.mp3)|(\w+\.py)$"def __init__(self, error_msg_dict=None, required=True):error_msg = {}  # {'required': '数字不能为空', 'valid': '数字格式错误'}if error_msg_dict:error_msg.update(error_msg_dict)super(FileField, self).__init__(error_msg_dict=error_msg, required=required)def match(self, name, value):self.name = nameself.value = []if not self.required:self.id_valid = Trueself.value = valueelse:if not value:if self.error_msg.get('required', None):self.error = self.error_msg['required']else:self.error = "%s is required" % nameelse:m = re.compile(self.REGULAR)if isinstance(value, list):for file_name in value:r = m.match(file_name)if r:self.value.append(r.group())self.id_valid = Trueelse:self.id_valid = Falseif self.error_msg.get('valid', None):self.error = self.error_msg['valid']else:self.error = "%s is invalid" % namebreakelse:if self.error_msg.get('valid', None):self.error = self.error_msg['valid']else:self.error = "%s is invalid" % namedef save(self, request, upload_path=""):file_metas = request.files[self.name]for meta in file_metas:file_name = meta['filename']with open(file_name,'wb') as up:up.write(meta['body'])class Form(object):def __init__(self):self.value_dict = {}self.error_dict = {}self.valid_status = Truedef validate(self, request, depth=10, pre_key=""):self.initialize()self.__valid(self, request, depth, pre_key)def initialize(self):passdef __valid(self, form_obj, request, depth, pre_key):"""验证用户表单请求的数据:param form_obj: Form对象（Form派生类的对象）:param request: Http请求上下文（用于从请求中获取用户提交的值）:param depth: 对Form内容的深度的支持:param pre_key: Html中name属性值的前缀（多层Form时，内部递归时设置，无需理会）:return: 是否验证通过，True：验证成功；False：验证失败"""depth -= 1if depth < 0:return Noneform_field_dict = form_obj.__dict__for key, field_obj in form_field_dict.items():print key,field_objif isinstance(field_obj, Form) or isinstance(field_obj, Field):if isinstance(field_obj, Form):# 获取以key开头的所有的值，以参数的形式传至self.__valid(field_obj, request, depth, key)continueif pre_key:key = "%s.%s" % (pre_key, key)if isinstance(field_obj, CheckBoxField):post_value = request.get_arguments(key, None)elif isinstance(field_obj, FileField):post_value = []file_list = request.request.files.get(key, None)for file_item in file_list:post_value.append(file_item['filename'])else:post_value = request.get_argument(key, None)print post_value# 让提交的数据 和 定义的正则表达式进行匹配field_obj.match(key, post_value)if field_obj.id_valid:self.value_dict[key] = field_obj.valueelse:self.error_dict[key] = field_obj.errorself.valid_status = Falseclass ListForm(object):def __init__(self, form_type):self.form_type = form_typeself.valid_status = Trueself.value_dict = {}self.error_dict = {}def validate(self, request):name_list = request.request.arguments.keys() + request.request.files.keys()index = 0flag = Falsewhile True:pre_key = "[%d]" % indexfor name in name_list:if name.startswith(pre_key):flag = Truebreakif flag:form_obj = self.form_type()form_obj.validate(request, depth=10, pre_key="[%d]" % index)if form_obj.valid_status:self.value_dict[index] = form_obj.value_dictelse:self.error_dict[index] = form_obj.error_dictself.valid_status = Falseelse:breakindex += 1flag = Falseclass MainForm(Form):def __init__(self):# self.ip = IPField(required=True)# self.port = IntegerField(required=True)# self.new_ip = IPField(required=True)# self.second = SecondForm()self.fff = FileField(required=True)super(MainForm, self).__init__()#
# class SecondForm(Form):
#
#     def __init__(self):
#         self.ip = IPField(required=True)
#         self.new_ip = IPField(required=True)
#
#         super(SecondForm, self).__init__()class MainHandler(tornado.web.RequestHandler):def get(self):self.render('index.html')def post(self, *args, **kwargs):# for i in  dir(self.request):#     print i# print self.request.arguments# print self.request.files# print self.request.query# name_list = self.request.arguments.keys() + self.request.files.keys()# print name_list# list_form = ListForm(MainForm)# list_form.validate(self)## print list_form.valid_status# print list_form.value_dict# print list_form.error_dict# obj = MainForm()# obj.validate(self)## print "验证结果：", obj.valid_status# print "符合验证结果：", obj.value_dict# print "错误信息:"# for key, item in obj.error_dict.items():#     print key,item# print self.get_arguments('favor'),type(self.get_arguments('favor'))# print self.get_argument('favor'),type(self.get_argument('favor'))# print type(self.get_argument('fff')),self.get_argument('fff')# print self.request.files# obj = MainForm()# obj.validate(self)# print obj.valid_status# print obj.value_dict# print obj.error_dict# print self.request,type(self.request)# obj.fff.save(self.request)# from tornado.httputil import HTTPServerRequest# name_list = self.request.arguments.keys() + self.request.files.keys()# print name_list# print self.request.files,type(self.request.files)# print len(self.request.files.get('fff'))# obj = MainForm()# obj.validate(self)# print obj.valid_status# print obj.value_dict# print obj.error_dict# obj.fff.save(self.request)self.write('ok')settings = {'template_path': 'template','static_path': 'static','static_url_prefix': '/static/','cookie_secret': 'aiuasdhflashjdfoiuashdfiuh','login_url': '/login'
}application = tornado.web.Application([(r"/index", MainHandler),
], **settings)if __name__ == "__main__":application.listen(8888)tornado.ioloop.IOLoop.instance().start()