Python Tornado简介
简介
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。
Tornado安装
pip3 install tornado
初识Tornado
首先打开pycharm，新建一个干净的project
新建一个py文件：
import tornado.ioloop import tornado.web class MainHandler(tornado.web.RequestHandler): # 类似于Django里面的CBV def get(self): # get方法 self.write("Hello, world") application = tornado.web.Application([ # 类似于Django里面的路由系统 (r"/index", MainHandler), ]) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start() # 启动
运行文件并打开浏览器访问网址：
运行该脚本，依次执行：
- 创建一个Application对象，并把一个正则表达式'/'和类名MainHandler传入构造函数：tornado.web.Application(...)
- 执行Application对象的listen(...)方法，即：application.listen(8888)
- 执行IOLoop类的类的 start() 方法，即：tornado.ioloop.IOLoop.instance().start()
整个过程其实就是在创建一个socket服务端并监听8888端口，当请求到来时，根据请求中的url和请求方式（post、get或put等）来指定相应的类中的方法来处理本次请求，在上述demo中只为url为http://127.0.0.1:8888/index的请求指定了处理类MainHandler（具体如何寻找见下文）。所以，在浏览器上访问：http://127.0.0.1:8888/index，则服务器给浏览器就会返回 Hello,world ，否则返回 404: Not Found（tornado内部定义的值）， 即完成一次http请求和响应。
由上述分析，我们将整个Web框架分为两大部分：
- 待请求阶段，即：创建服务端socket并监听端口
- 处理请求阶段，即：当有客户端连接时，接受请求，并根据请求的不同做出相应的相应
经典的Login案例
首先，创建模版文件夹和模版文件：
login.html文件
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form method="POST" action="/login"> <input type="text" name="username" /> <input type="submit" value="提交" /> </form> </body> </html>
新建一个路由：
(r"/login", LoginHandler),
新建CBV：
class LoginHandler(tornado.web.RequestHandler): def get(self): self.render("login.html") def post(self, *args, **kwargs): # 获取url中以GET形式传递的数据 self.get_query_argument() self.get_query_arguments() # 去请求体中获取传递的数据 self.get_body_argument() self.get_body_arguments() # 去get&post双方去取数据 user = self.get_argument('username') print(user) self.redirect('www.baidu.com')
注册模版文件路径：
# 申明settings，字典格式 settings = { 'template_path': 'tmp' } # 注册进tornado内部 application = tornado.web.Application([ (r"/index", MainHandler), (r"/login", LoginHandler), ], **settings)
整体app文件：
#!/usr/bin/env python3 # encoding: utf-8 # Author: Dandy import tornado.ioloop import tornado.web class MainHandler(tornado.web.RequestHandler): def get(self): self.write("Hello, world") class LoginHandler(tornado.web.RequestHandler): def get(self): self.render("login.html") def post(self, *args, **kwargs): # 获取url中以GET形式传递的数据 self.get_query_argument() self.get_query_arguments() # 去请求体中获取传递的数据 self.get_body_argument() self.get_body_arguments() # 去get&post双方去取数据 user = self.get_argument('username') print(user) self.redirect('www.baidu.com') settings = { 'template_path': 'tmp' } application = tornado.web.Application([ (r"/index", MainHandler), (r"/login", LoginHandler), ], **settings) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
此时便可执行
关于静态文件
首先添加静态文件夹，并放入一张图片
静态路径注册：
settings = { 'template_path': 'tmp', 'static_path': 'statics' }
login页面加入图片、注意以下路径写的是static，标准用法
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form method="POST" action="/login"> <input type="text" name="username" /> <input type="submit" value="提交" /> </form> <img src="/static/炫雅.jpeg" /> </body> </html>
此时访问页面
那能不能不用static作为静态文件夹名称呢？
答案当然是可以的，只需要这样注册：
settings = { 'template_path': 'tmp', 'static_path': 'statics', 'static_url_prefix': '/jingtai/', # 这里就是用户自定义的静态路径名称 }
再去修改login网页里的就好了。
详细介绍
上面简单的介绍了一下totornado的一些基本运用搭建。现在花点篇幅详细的解决各个模块的基本问题。
一、路由系统
路由系统从前面Django的学习过程中不难总结出来，其实就是url和视图函数的对应关系。当然啦，在Django里面，有FBV和CBV的概念；而在tornado每个url对应的函数均是一个类，即CBV。
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 HomeHandler(tornado.web.RequestHandler): def get(self): self.write("dandy") application = tornado.web.Application([ (r"/index", MainHandler), (r"/story/([0-9]+)", StoryHandler), ]) application.add_handlers(r"^a\.com$", [ (r"/", HomeHandler), # 路由a.com:8888/ ]) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
Tornado中原生支持二级域名的路由，如：
二、模版引擎
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。
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
import tornado.ioloop import tornado.web class MainHandler(tornado.web.RequestHandler): def get(self): self.render("index.html", list_info=[11, 22, 33], key1='value1') settings = { 'template_path': 'tmp' } application = tornado.web.Application([ (r"/index", MainHandler), ], **settings) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <link href='{{static_url("css/common.css")}}' rel="stylesheet" /> </head> <body> <h1>{{ key1 }}</h1> <ul> {% for item in list_info %} {% if item > 12 %} <li>{{ item }}</li> {% end %} {% end %} </ul> </body> </html>
类似于static_url的其他方法
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>title</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>
layout.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、导入小标签
<div>
<ul>
<li>dandy</li>
<li>durant</li>
</ul>
</div>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<title></title>
</head>
<body>
<div class="pg-header">
{% include 'header.html' %}
</div>
</body>
</html>
4、模版函数扩展UIMethod&UIModule
a、申明
def tab(self): return 'UIMethod'
from tornado.web import UIModule from tornado import escape class custom(UIModule): def render(self, *args, **kwargs): return escape.xhtml_escape('<h1>wuzdandz</h1>')
b、注册
import uimodules as md import uimethods as mt settings = { 'template_path': 'template', 'static_path': 'static', 'ui_methods': mt, 'ui_modules': md, }
c、使用
<body> {% module custom(123) %} <br> {{ tab() }} </body>
注意一下这几个方法：
embedded_css/javascript 用来产生css或js语句的
javascript/css_files用来产生link指向文件
三、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。
settings = { 'template_path': 'template', 'static_path': 'static', 'static_url_prefix': '/static/', } application = tornado.web.Application([ (r"/index", MainHandler), ], **settings)
<img src="/static/炫雅.jpeg" /> <link href='{{static_url("commons.css")}}' rel="stylesheet" />
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()
四、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("username"): # 获取cookie self.set_cookie("username", "dandy") # 设置cookie 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。
/*
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();
}
当然更推荐使用jquery cookie来操作cookie
五、CSRF
Tornado中的跨站请求伪造和Django中的相似
1、启用设置
settings = { "xsrf_cookies": True, } application = tornado.web.Application([ (r"/", MainHandler), (r"/login", LoginHandler), ], **settings)
2、表单
<form action="/new_message" method="post"> {% raw xsrf_form_html() %} <input type="text" name="message"/> <input type="submit" value="Post"/> </form>
3、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
六、上传文件
1、form表单上传
<body>
<form name="form" action="/index" method="POST" enctype="multipart/form-data" >
<input name="fafafa" id="my_file" type="file" />
<input type="submit" value="提交" />
</form>
</body>
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["fafafa"] # 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
<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>
<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>
<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>
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); } }) }) } 其他
七、异步非阻塞
1、基本使用
首先，先看一段代码
class AsyncHandler(tornado.web.RequestHandler): def get(self): import time time.sleep(20) self.write('666') application = tornado.web.Application([ (r"/index", MainHandler), (r"/async", AsyncHandler), ], **settings)
对于异步非阻塞的了解，第一点肯定是， 单线程；所以测试一下上面的代码，不难发现：先打开async页面，没有任何返回，一直显示在加载，此时打开index，发现index页面同时也在加载出不来。
当async执行完，index页面也很快就返回了。
此时修改一下代码：
#!/usr/bin/env python # -*- coding:utf-8 -*- import tornado.ioloop import tornado.web from tornado.web import UIModule from tornado import gen from tornado.concurrent import Future import time class MainHandler(tornado.web.RequestHandler): def get(self): self.render("index.html", list_info=[11, 22, 33], key1='value1') class AsyncHandler(tornado.web.RequestHandler): @gen.coroutine def get(self): future = Future() tornado.ioloop.IOLoop.current().add_timeout(time.time() + 20, self.doing) yield future def doing(self, *args, **kwargs): self.write('async') self.finish() settings = { 'template_path': 'tmp', 'static_path': 'statics' } application = tornado.web.Application([ (r"/index", MainHandler), (r"/async", AsyncHandler), ], **settings) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
此时再执行上面的操作，就会发现当async阻塞等待返回的时候，其他网页是可以继续访问的。这样单位时间处理的请求也就更多了。在服务器端将单线程用到极致。
装饰器 + Future 从而实现Tornado的异步非阻塞，异步非阻塞的核心其实就在这个Future上，这个future类有点类似于一个标记，当装饰器装饰函数，函数内部实例化Future，并添加回调函数后。执行代码：
from tornado import gen from tornado.concurrent import Future 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()
发现请求一直没有返回。实际上实例化future之后，产生了一个flag，只有当准备好响应数据或者满足响应条件的时候才可以回调callback函数，返回给客户端。
2、同步阻塞与异步非阻塞对比
前面的第一个实例其实就是同步阻塞的实例了。
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，可以配合异步非阻塞使用。
import tornado.web from tornado import gen from tornado import httpclient # 方式一： class AsyncHandler(tornado.web.RequestHandler): @gen.coroutine def get(self, *args, **kwargs): print('进入') http = httpclient.AsyncHTTPClient() data = yield http.fetch("http://www.google.com") print('K.O.',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('K.O.') # self.finish('666') application = tornado.web.Application([ (r"/async", AsyncHandler), ]) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
说到这，我们来测试下通过另一个url来改变future的标记位。
补充：
import tornado.ioloop import tornado.web from tornado.web import UIModule from tornado import gen from tornado.concurrent import Future future = None class MainHandler(tornado.web.RequestHandler): def get(self): self.render("index.html", list_info=[11, 22, 33], key1='value1') class AsyncHandler(tornado.web.RequestHandler): @gen.coroutine def get(self): global future 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() class StopHandler(tornado.web.RequestHandler): def get(self, *args, **kwargs): future.set_result('...') settings = { 'template_path': 'tmp', 'static_path': 'statics' } application = tornado.web.Application([ (r"/index", MainHandler), (r"/async", AsyncHandler), (r"/stop", StopHandler), ], **settings) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
200行的自定义异步非阻塞web框架
#!/usr/bin/env python3 # encoding: utf-8 # Author: Dandy import re import socket import select import time class HttpResponse(object): """ 封装响应信息 """ def __init__(self, content=''): self.content = content self.headers = {} self.cookies = {} def response(self): return bytes(self.content, encoding='utf-8') class HttpNotFound(HttpResponse): """ 404时的错误提示 """ def __init__(self): super(HttpNotFound, self).__init__('404 Not Found') class HttpRequest(object): """ 用户封装用户请求信息 """ def __init__(self, conn): self.conn = conn self.header_bytes = bytes() self.header_dict = {} self.body_bytes = bytes() self.method = "" self.url = "" self.protocol = "" self.initialize() self.initialize_headers() def initialize(self): header_flag = False while True: try: received = self.conn.recv(8096) except Exception as e: received = None if not received: break if header_flag: self.body_bytes += received continue temp = received.split(b'\r\n\r\n', 1) if len(temp) == 1: self.header_bytes += temp else: h, b = temp self.header_bytes += h self.body_bytes += b header_flag = True @property def header_str(self): return str(self.header_bytes, encoding='utf-8') def initialize_headers(self): headers = self.header_str.split('\r\n') first_line = headers[0].split(' ') if len(first_line) == 3: self.method, self.url, self.protocol = headers[0].split(' ') for line in headers: kv = line.split(':') if len(kv) == 2: k, v = kv self.header_dict[k] = v class Future(object): """ 异步非阻塞模式时封装回调函数以及是否准备就绪 """ def __init__(self, callback): self.callback = callback self._ready = False self.value = None def set_result(self, value=None): self.value = value self._ready = True @property def ready(self): return self._ready class TimeoutFuture(Future): """ 异步非阻塞超时 """ def __init__(self, timeout): super(TimeoutFuture, self).__init__(callback=None) self.timeout = timeout self.start_time = time.time() @property def ready(self): current_time = time.time() if current_time > self.start_time + self.timeout: self._ready = True return self._ready class Snow(object): """ 微型Web框架类 """ def __init__(self, routes): self.routes = routes self.inputs = set() self.request = None self.async_request_handler = {} def run(self, host='localhost', port=9999): """ 事件循环 :param host: :param port: :return: """ sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) sock.bind((host, port,)) sock.setblocking(False) # 非阻塞 sock.listen(128) sock.setblocking(0) self.inputs.add(sock) # 将此socket添加到inputs这个集合里 try: while True: readable_list, writeable_list, error_list = select.select(self.inputs, [], self.inputs,0.005) # 监听 for conn in readable_list: # 循环可读的集合 if sock == conn: # socket有新的连接进来 client, address = conn.accept() # 获取conn、addr client.setblocking(False) self.inputs.add(client) # 将此连接conn加入监听 else: gen = self.process(conn) # 获取、处理连接conn，拿请求体请求体 if isinstance(gen, HttpResponse): # 如果返回的是HttpResponse类型的，代表是正常的请求 conn.sendall(gen.response()) # 发送给客户端 self.inputs.remove(conn) # 既然返回了，则需要从监听队列移除 conn.close() # 关闭此socket连接 else: yielded = next(gen) # 不是正常的请求就必定是yield future self.async_request_handler[conn] = yielded # future对象加入字典中key==》conn，value==》future对象 self.polling_callback() # for 循环执行完，执行此函数 except Exception as e: pass finally: sock.close() def polling_callback(self): """ 遍历触发异步非阻塞的回调函数 :return: """ for conn in list(self.async_request_handler.keys()): # 循环取key yielded = self.async_request_handler[conn] # 根据循环的key取value # conn：socket对象 # yielded：future对象 if not yielded.ready: # ready是布尔值，如果执行了set_result，就变成true，表示已经就绪 continue # 否则循环继续 if yielded.callback: # 如果被set result ret = yielded.callback(self.request, yielded) conn.sendall(ret.response()) # 发送数据 self.inputs.remove(conn) # 从监听内移除此conn del self.async_request_handler[conn] # 从循环字典删除 conn.close() # 关闭conn def process(self, conn): """ 处理路由系统以及执行函数 :param conn: :return: """ self.request = HttpRequest(conn) func = None for route in self.routes: if re.match(route[0], self.request.url): func = route[1] break if not func: return HttpNotFound() else: return func(self.request)
使用
from snow import Snow from snow import HttpResponse def index(request): return HttpResponse('OK') routes = [ (r'/index/', index), ] app = Snow(routes) app.run(port=8012)
from snow import Snow from snow import HttpResponse from snow import TimeoutFuture request_list = [] def async(request): obj = TimeoutFuture(5) yield obj def home(request): return HttpResponse('home') routes = [ (r'/home/', home), (r'/async/', async), ] app = Snow(routes) app.run(port=8012)
from snow import Snow from snow import HttpResponse from snow import Future request_list = [] def callback(request, future): return HttpResponse(future.value) def req(request): obj = Future(callback=callback) request_list.append(obj) yield obj def stop(request): obj = request_list[0] del request_list[0] obj.set_result('done') return HttpResponse('stop') routes = [ (r'/req/', req), (r'/stop/', stop), ] app = Snow(routes) app.run(port=8012)
基于等待模式可以完成自定制操作
本blog参考自：https://www.cnblogs.com/wupeiqi/p/6536518.html
