WEBAPP开发教程Tornado-职坐标

WEBAPP开发教程Tornado

凌雪 2018-10-25 来源：网络阅读 990 评论 0

摘要：本文将带你了解WEBAPP开发教程Tornado，希望本文对大家学WEBAPP有所帮助。

本文将带你了解WEBAPP开发教程Tornado，希望本文对大家学WEBAPP有所帮助。

概述
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

框架使用
一、快速上手

#!/usr/bin/env
python

#
-*- coding:utf-8 -*-



import tornado.ioloop

import tornado.web





class 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 --> //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

#!/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 gen

import uimodules as md
import uimethods as mt

class MainHandler(tornado.web.RequestHandler):
        @asynchronous
        @gen.coroutine
        def get(self):
            print 'start get '
            http = httpclient.AsyncHTTPClient()
            http.fetch("//127.0.0.1:8008/post/", self.callback)
            self.write('end')

        def callback(self, response):
            print response.body

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()

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.web





class 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：

三、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

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import tornado.ioloop
import tornado.web

class 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()

<!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>

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

<!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>

    </div>

    {% block RenderBody %}{% end %}

    <script src="{{static_url("js/jquery-1.8.2.min.js")}}"></script>

    {% block JavaScript %}{% end %}
</body>
</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

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

<!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>
        {% 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
a. 定义

# uimethods.py

def tab(self):
    return 'UIMethod'

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from tornado.web import UIModule
from tornado import escape

class custom(UIModule):

   def render(self, *args, **kwargs):
        return escape.xhtml_escape('<h1>wupeiqi</h1>')
        #return escape.xhtml_escape('<h1>wupeiqi</h1>')

b. 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 mt

class 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()

c. 使用

<!DOCTYPE html>
<html>
<head>
    <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。

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import tornado.ioloop
import tornado.web

class 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()

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

注：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. The
        default 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=")

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_VERSION
    if clock is None:
        clock = time.time

    timestamp = 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 value
    elif 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 + signature
    else:
        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 None
    signature = _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 None
    timestamp = int(parts[1])
    if timestamp < clock() - max_age_days * 86400:
        gen_log.warning("Expired cookie %r", value)
        return None
    if 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 None
    if parts[1].startswith(b"0"):
        gen_log.warning("Tampered cookie %r", value)
        return None
    try:
        return base64.b64decode(parts[0])
    except Exception:
        return None

def _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, rest

    rest = value[2:] # remove version number
    key_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_sig

def _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 None
    signed_string = value[:-len(passed_sig)]

    if isinstance(secret, dict):
        try:
            secret = secret[key_version]
        except KeyError:
            return None

    expected_sig = _create_signature_v2(secret, signed_string)
    if not _time_independent_equals(passed_sig, expected_sig):
        return None
    if name_field != utf8(name):
        return None
    timestamp = int(timestamp)
    if timestamp < clock() - max_age_days * 86400:
        # The signature has expired.
        return None
    try:
        return base64.b64decode(value_field)
    except Exception:
        return None

def get_signature_key_version(value):
    value = utf8(value)
    version = _get_version(value)
    if version < 2:
        return None
    try:
        key_version, _, _, _, _ = _decode_fields_v2(value)
    except ValueError:
        return None

    return 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。

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import tornado.ioloop
import tornado.web

class 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()

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import tornado.ioloop
import tornado.web

class BaseHandler(tornado.web.RequestHandler):

    def get_current_user(self):
        return self.get_secure_cookie("login_user")

class MainHandler(BaseHandler):

    @tornado.web.authenticated
    def get(self):
        login_user = self.current_user
        self.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。

1

2

3

4

5

6

7

8

9

/*

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cookiepath 域名下指定url中的cookiesecure 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)

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

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

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

<!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>

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import tornado.ioloop
import tornado.web

class 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

<!DOCTYPE html>
<html>
<head>
    <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>

<!DOCTYPE html>
<html>
<head>
    <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 data
                contentType: false, // tell jQuery not to set contentType
                success: function(arg){
                    console.log(arg);
                }
            })
        }
    </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
    <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>

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import tornado.ioloop
import tornado.web

class 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()

<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>

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

                })

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 data
                    contentType: false, // tell jQuery not to set contentType
                    success: 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：

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pip3
install pillow

示例截图：

验证码Demo源码下载：猛击这里
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

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class AsyncHandler(tornado.web.RequestHandler):

    @gen.coroutine

    def get(self):

        future = Future()

        future.add_done_callback(self.doing)

        yield future

        #
或

        #
tornado.ioloop.IOLoop.current().add_future(future,self.doing)

        #
yield future

    def 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

class SyncHandler(tornado.web.RequestHandler):

    def get(self):
        self.doing()
        self.write('sync')

    def doing(self):
      time.sleep(10)

class AsyncHandler(tornado.web.RequestHandler):
    @gen.coroutine
    def get(self):
        future = Future()
        tornado.ioloop.IOLoop.current().add_timeout(time.time() + 5, self.doing)
        yield future

    def 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。

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class AsyncHandler(tornado.web.RequestHandler):

    @gen.coroutine

    def get(self):

        from tornado import httpclient

        http = httpclient.AsyncHTTPClient()

        yield http.fetch("//www.google.com", self.endding)

    def endding(self,
response):

        print(len(response.body))

        self.write('ok')

        self.finish()

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

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#!/usr/bin/env
python

#
-*- coding:utf-8 -*-



class Foo(object):



    def __getitem__(self,
key):

        print  '__getitem__',key



    def __setitem__(self,
key, value):

        print '__setitem__',key,value



    def __delitem__(self,
key):

        print '__delitem__',key







obj = 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...

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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。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import config
from hashlib import sha1
import os
import time

create_session_id = lambda: sha1(bytes('%s%s' % (os.urandom(16), time.time()), encoding='utf-8')).hexdigest()

class SessionFactory:

    @staticmethod
    def get_session_obj(handler):
        obj = None

        if config.SESSION_TYPE == "cache":
            obj = CacheSession(handler)
        elif config.SESSION_TYPE == "memcached":
            obj = MemcachedSession(handler)
        elif config.SESSION_TYPE == "redis":
            obj = RedisSession(handler)
        return obj

class CacheSession:
    session_container = {}
    session_id = "__sessionId__"

    def __init__(self, handler):
        self.handler = handler
        client_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_str
        else:
            self.random_str = create_session_id()
            CacheSession.session_container[self.random_str] = {}

        expires_time = time.time() + config.SESSION_EXPIRES
        handler.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 ret

    def __setitem__(self, key, value):
        CacheSession.session_container[self.random_str][key] = value

    def __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):
        pass

class MemcachedSession:
    def __init__(self, handler):
        pass

4、分布式Session

#!/usr/bin/env python
#coding:utf-8

import sys
import math
from bisect import bisect

if sys.version_info >= (2, 5):
    import hashlib
    md5_constructor = hashlib.md5
else:
    import md5
    md5_constructor = md5.new

class 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 = 0

        self.__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