Application：
可以理解成是用来配置httpserver如何影响客户端请求的配置项集合的类，用户在main函数里配置好这个类里的各项数据，再直接传递给HTTPServer，启动一个web应用。
这个类初始化最重要的一个参数是handlers，它是一个由多个（包含1个）元组（结构为（regexp, request_class））组成的列表，其中的regexp一般指向一个相对路径，request_class就是用来接收客户端输入并做出对应响应类，一般由用户自定义，继承于tornado.web.RequestHandler，这个regexp和request_class是怎么起作用，需要详细阅读RequestHandler类
class Application(httputil.HTTPServerConnectionDelegate):
"""A collection of request handlers that make up a web application.
Instances of this class are callable and can be passed directly to
HTTPServer to serve the application::
application = web.Application([
(r"/", MainPageHandler),
])
http_server = httpserver.HTTPServer(application)
http_server.listen(8080)
ioloop.IOLoop.instance().start()
The constructor for this class takes in a list of `URLSpec` objects
or (regexp, request_class) tuples. When we receive requests, we
iterate over the list in order and instantiate an instance of the
first request class whose regexp matches the request path.
The request class can be specified as either a class object or a
(fully-qualified) name.
Each tuple can contain additional elements, which correspond to the
arguments to the `URLSpec` constructor. (Prior to Tornado 3.2, this
only tuples of two or three elements were allowed).
A dictionary may be passed as the third element of the tuple,
which will be used as keyword arguments to the handler‘s
constructor and `~RequestHandler.initialize` method. This pattern
is used for the `StaticFileHandler` in this example (note that a
`StaticFileHandler` can be installed automatically with the
static_path setting described below)::
application = web.Application([
(r"/static/(.*)", web.StaticFileHandler, {"path": "/var/www"}),
])
We support virtual hosts with the `add_handlers` method, which takes in
a host regular expression as the first argument::
application.add_handlers(r"www\.myhost\.com", [
(r"/article/([0-9]+)", ArticleHandler),
])
You can serve static files by sending the ``static_path`` setting
as a keyword argument. We will serve those files from the
``/static/`` URI (this is configurable with the
``static_url_prefix`` setting), and we will serve ``/favicon.ico``
and ``/robots.txt`` from the same directory. A custom subclass of
`StaticFileHandler` can be specified with the
``static_handler_class`` setting.
"""
def __init__(self, handlers=None, default_host="", transforms=None,
**settings):
if transforms is None:
self.transforms = []
if settings.get("compress_response") or settings.get("gzip"):
self.transforms.append(GZipContentEncoding)
else:
self.transforms = transforms
self.handlers = []
self.named_handlers = {}
self.default_host = default_host
self.settings = settings
self.ui_modules = {‘linkify‘: _linkify,
‘xsrf_form_html‘: _xsrf_form_html,
‘Template‘: TemplateModule,
}
self.ui_methods = {}
self._load_ui_modules(settings.get("ui_modules", {}))
self._load_ui_methods(settings.get("ui_methods", {}))
if self.settings.get("static_path"):
path = self.settings["static_path"]
handlers = list(handlers or [])
static_url_prefix = settings.get("static_url_prefix",
"/static/")
static_handler_class = settings.get("static_handler_class",
StaticFileHandler)
static_handler_args = settings.get("static_handler_args", {})
static_handler_args[‘path‘] = path
for pattern in [re.escape(static_url_prefix) + r"(.*)",
r"/(favicon\.ico)", r"/(robots\.txt)"]:
handlers.insert(0, (pattern, static_handler_class,
static_handler_args))
if handlers:
self.add_handlers(".*$", handlers)
if self.settings.get(‘debug‘):
self.settings.setdefault(‘autoreload‘, True)
self.settings.setdefault(‘compiled_template_cache‘, False)
self.settings.setdefault(‘static_hash_cache‘, False)
self.settings.setdefault(‘serve_traceback‘, True)
# Automatically reload modified modules
if self.settings.get(‘autoreload‘):
from tornado import autoreload
autoreload.start()
def listen(self, port, address="", **kwargs):
"""Starts an HTTP server for this application on the given port.
This is a convenience alias for creating an `.HTTPServer`
object and calling its listen method. Keyword arguments not
supported by `HTTPServer.listen <.TCPServer.listen>` are passed to the
`.HTTPServer` constructor. For advanced uses
(e.g. multi-process mode), do not use this method; create an
`.HTTPServer` and call its
`.TCPServer.bind`/`.TCPServer.start` methods directly.
Note that after calling this method you still need to call
``IOLoop.instance().start()`` to start the server.
"""
# import is here rather than top level because HTTPServer
# is not importable on appengine
from tornado.httpserver import HTTPServer
server = HTTPServer(self, **kwargs)
server.listen(port, address)
def add_handlers(self, host_pattern, host_handlers):
"""Appends the given handlers to our handler list.
Host patterns are processed sequentially in the order they were
added. All matching patterns will be considered.
"""
if not host_pattern.endswith("$"):
host_pattern += "$"
handlers = []
# The handlers with the wildcard host_pattern are a special
# case - they‘re added in the constructor but should have lower
# precedence than the more-precise handlers added later.
# If a wildcard handler group exists, it should always be last
# in the list, so insert new groups just before it.
if self.handlers and self.handlers[-1][0].pattern == ‘.*$‘:
self.handlers.insert(-1, (re.compile(host_pattern), handlers))
else:
self.handlers.append((re.compile(host_pattern), handlers))
for spec in host_handlers:
if isinstance(spec, (tuple, list)):
assert len(spec) in (2, 3, 4)
spec = URLSpec(*spec)
handlers.append(spec)
if spec.name:
if spec.name in self.named_handlers:
app_log.warning(
"Multiple handlers named %s; replacing previous value",
spec.name)
self.named_handlers[spec.name] = spec
def add_transform(self, transform_class):
self.transforms.append(transform_class)
def _get_host_handlers(self, request):
host = split_host_and_port(request.host.lower())[0]
matches = []
for pattern, handlers in self.handlers:
if pattern.match(host):
matches.extend(handlers)
# Look for default host if not behind load balancer (for debugging)
if not matches and "X-Real-Ip" not in request.headers:
for pattern, handlers in self.handlers:
if pattern.match(self.default_host):
matches.extend(handlers)
return matches or None
def _load_ui_methods(self, methods):
if isinstance(methods, types.ModuleType):
self._load_ui_methods(dict((n, getattr(methods, n))
for n in dir(methods)))
elif isinstance(methods, list):
for m in methods:
self._load_ui_methods(m)
else:
for name, fn in methods.items():
if not name.startswith("_") and hasattr(fn, "__call__") and name[0].lower() == name[0]:
self.ui_methods[name] = fn
def _load_ui_modules(self, modules):
if isinstance(modules, types.ModuleType):
self._load_ui_modules(dict((n, getattr(modules, n))
for n in dir(modules)))
elif isinstance(modules, list):
for m in modules:
self._load_ui_modules(m)
else:
assert isinstance(modules, dict)
for name, cls in modules.items():
try:
if issubclass(cls, UIModule):
self.ui_modules[name] = cls
except TypeError:
pass
def start_request(self, server_conn, request_conn):
# Modern HTTPServer interface
return _RequestDispatcher(self, request_conn)
def __call__(self, request):
# Legacy HTTPServer interface
dispatcher = _RequestDispatcher(self, None)
dispatcher.set_request(request)
return dispatcher.execute()
def reverse_url(self, name, *args):
"""Returns a URL path for handler named ``name``
The handler must be added to the application as a named `URLSpec`.
Args will be substituted for capturing groups in the `URLSpec` regex.
They will be converted to strings if necessary, encoded as utf8,
and url-escaped.
"""
if name in self.named_handlers:
return self.named_handlers[name].reverse(*args)
raise KeyError("%s not found in named urls" % name)
def log_request(self, handler):
"""Writes a completed HTTP request to the logs.
By default writes to the python root logger. To change
this behavior either subclass Application and override this method,
or pass a function in the application settings dictionary as
``log_function``.
"""
if "log_function" in self.settings:
self.settings["log_function"](handler)
return
if handler.get_status() < 400:
log_method = access_log.info
elif handler.get_status() < 500:
log_method = access_log.warning
else:
log_method = access_log.error
request_time = 1000.0 * handler.request.request_time()
log_method("%d %s %.2fms", handler.get_status(),
handler._request_summary(), request_time)原文：http://my.oschina.net/u/703355/blog/412165