#!/usr/bin/env python
#
# Copyright 2009
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import markdown
import os.path
import re
import torndb
import tornado.auth
import tornado.httpserver
import tornado.ioloop
import tornado.options
import tornado.web
import unicodedata

from tornado.options import define, options
#定义一些通用的配置信息，比如数据库的连接信息，端口信息
define("port", default=8888, help="run on the given port", type=int)
define("mysql_host", default="127.0.0.1:3306", help="blog database host")
define("mysql_database", default="blog", help="blog database name")
define("mysql_user", default="root", help="blog database user")
define("mysql_password", default="sa123", help="blog database password")

#定义Application信息，它是继承tornado.web.Application 的
class Application(tornado.web.Application):
　　 # __init__ 函数自动调用
def __init__(self):
　　 #这里就是url对应的控制器，下面分别对应一个类，来处理里面的逻辑
handlers = [
(r"/", HomeHandler),
(r"/archive", ArchiveHandler),
(r"/feed", FeedHandler),
(r"/entry/([^/]+)", EntryHandler),
(r"/compose", ComposeHandler),
(r"/auth/login", AuthLoginHandler),
(r"/auth/logout", AuthLogoutHandler),
]
　　 #设置，如博客标题，模板目录，静态文件目录，xsrf，是否调试
settings = dict(
blog_title=u"Tornado Blog",
template_path=os.path.join(os.path.dirname(__file__), "templates"),
static_path=os.path.join(os.path.dirname(__file__), "static"),
ui_modules={"Entry": EntryModule},
xsrf_cookies=True,
cookie_secret="__TODO:_GENERATE_YOUR_OWN_RANDOM_VALUE_HERE__",
login_url="/auth/login",
debug=True,
)
　　 #然后调用tornado.web.Application类的__init__函数加载进来
tornado.web.Application.__init__(self, handlers, **settings)

# Have one global connection to the blog DB across all handlers
　　 #数据库连接信息
self.db = torndb.Connection(
host=options.mysql_host, database=options.mysql_database,
user=options.mysql_user, password=options.mysql_password)

#基类，继承自tornado.web.RequestHandler 的，后面的类都是继承这个类的
class BaseHandler(tornado.web.RequestHandler):
　　#属性装饰器，使db函数变成一个属性，便于后面直接使用
@property
def db(self):
return self.application.db
　　#获得当前的用户
def get_current_user(self):
user_id = self.get_secure_cookie("blogdemo_user")
if not user_id: return None
return self.db.get("SELECT * FROM authors WHERE id = %s", int(user_id))

#首页
class HomeHandler(BaseHandler):
def get(self):
　　　　 #query 查询很多列
entries = self.db.query("SELECT * FROM entries ORDER BY published "
"DESC LIMIT 5")
if not entries:
　　　　 #redirect 重定向到一个url
self.redirect("/compose")
return
　　　　 #render 渲染一个模板，后面是参数
self.render("home.html", entries=entries)

class EntryHandler(BaseHandler):
def get(self, slug):
　　　　#get 得到一个值
entry = self.db.get("SELECT * FROM entries WHERE slug = %s", slug)
　　　　#raise 触发一个错误信息，后面必须接类型
if not entry: raise tornado.web.HTTPError(404)
self.render("entry.html", entry=entry)

class ArchiveHandler(BaseHandler):
def get(self):
entries = self.db.query("SELECT * FROM entries ORDER BY published "
"DESC")
self.render("archive.html", entries=entries)

class FeedHandler(BaseHandler):
def get(self):
entries = self.db.query("SELECT * FROM entries ORDER BY published "
"DESC LIMIT 10")
self.set_header("Content-Type", "application/atom+xml")
self.render("feed.xml", entries=entries)

class ComposeHandler(BaseHandler):
#装饰器
@tornado.web.authenticated
def get(self):
id = self.get_argument("id", None)
entry = None
if id:
entry = self.db.get("SELECT * FROM entries WHERE id = %s", int(id))
self.render("compose.html", entry=entry)

@tornado.web.authenticated
def post(self):
id = self.get_argument("id", None)
title = self.get_argument("title")
text = self.get_argument("markdown")
html = markdown.markdown(text)
if id:
entry = self.db.get("SELECT * FROM entries WHERE id = %s", int(id))
if not entry: raise tornado.web.HTTPError(404)
slug = entry.slug
　　 #execute是执行的意思
self.db.execute(
"UPDATE entries SET title = %s, markdown = %s, html = %s "
"WHERE id = %s", title, text, html, int(id))
else:
slug = unicodedata.normalize("NFKD", title).encode(
"ascii", "ignore")
slug = re.sub(r"[^\w]+", " ", slug)
slug = "-".join(slug.lower().strip().split())
if not slug: slug = "entry"
while True:
e = self.db.get("SELECT * FROM entries WHERE slug = %s", slug)
if not e: break
slug += "-2"
self.db.execute(
"INSERT INTO entries (author_id,title,slug,markdown,html,"
"published) VALUES (%s,%s,%s,%s,%s,UTC_TIMESTAMP())",
self.current_user.id, title, slug, text, html)
self.redirect("/entry/" + slug)

class AuthLoginHandler(BaseHandler, tornado.auth.GoogleMixin):
@tornado.web.asynchronous
def get(self):
if self.get_argument("openid.mode", None):
self.get_authenticated_user(self.async_callback(self._on_auth))
return
self.authenticate_redirect()
　　#这里定义一个函数，来供上面调用
def _on_auth(self, user):
if not user:
raise tornado.web.HTTPError(500, "Google auth failed")
author = self.db.get("SELECT * FROM authors WHERE email = %s",
user["email"])
if not author:
# Auto-create first author
any_author = self.db.get("SELECT * FROM authors LIMIT 1")
if not any_author:
author_id = self.db.execute(
"INSERT INTO authors (email,name) VALUES (%s,%s)",
user["email"], user["name"])
else:
self.redirect("/")
return
else:
author_id = author["id"]
self.set_secure_cookie("blogdemo_user", str(author_id))
self.redirect(self.get_argument("next", "/"))

class AuthLogoutHandler(BaseHandler):
def get(self):
self.clear_cookie("blogdemo_user")
　　 #get_argument为获得next参数的值，默认为"/"
self.redirect(self.get_argument("next", "/"))

class EntryModule(tornado.web.UIModule):
def render(self, entry):
return self.render_string("modules/entry.html", entry=entry)

#入口函数
def main():
tornado.options.parse_command_line()
　 #创建一个服务器
http_server = tornado.httpserver.HTTPServer(Application())
　 #监听端口
http_server.listen(options.port)
　　#启动服务
tornado.ioloop.IOLoop.instance().start()

#调用的入口
if __name__ == "__main__":
main()

最后总结一下：

1）tornado框架中提供的几个demo，都是以这种形式来创建一个应用的
2）对每一个控制器函数，要么是，只可能有2个对外的函数，一个是get，一个是post
3）数据库有3中调用方式，query，get，exec
4）获取参数的值使用 get_argument 函数
5）重定向用redirect 函数
6）所有的函数都是属性这个类的，所有都用self调用
7）渲染模板用render函数