浅析tornado 中demo的 blog模块

#!/usr/bin/env python
#
# Copyright 2009 Facebook
#
# 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