tornado.httpclient — 异步 HTTP 客户端
Blocking and non-blocking HTTP client interfaces.
This module defines a common interface shared by two implementations,
simple_httpclient and curl_httpclient. Applications may either
instantiate their chosen implementation class directly or use the
AsyncHTTPClient class from this module, which selects an implementation
that can be overridden with the AsyncHTTPClient.configure method.
The default implementation is simple_httpclient, and this is expected
to be suitable for most users’ needs. However, some applications may wish
to switch to curl_httpclient for reasons such as the following:
- curl_httpclient has some features not found in simple_httpclient,
including support for HTTP proxies and the ability to use a specified
network interface.
- curl_httpclient is more likely to be compatible with sites that are
not-quite-compliant with the HTTP spec, or sites that use little-exercised
features of HTTP.
- curl_httpclient is faster.
- curl_httpclient was the default prior to Tornado 2.0.
Note that if you are using curl_httpclient, it is highly recommended that
you use a recent version of libcurl and pycurl. Currently the minimum
supported version is 7.18.2, and the recommended version is 7.21.1 or newer.
HTTP 客户端接口
-
class tornado.httpclient.HTTPClient(async_client_class=None, **kwargs)[源代码]
A blocking HTTP client.
This interface is provided for convenience and testing; most applications
that are running an IOLoop will want to use AsyncHTTPClient instead.
Typical usage looks like this:
http_client = httpclient.HTTPClient()
try:
response = http_client.fetch("http://www.google.com/")
print response.body
except httpclient.HTTPError as e:
print "Error:", e
http_client.close()
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close()[源代码]
Closes the HTTPClient, freeing any resources used.
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fetch(request, **kwargs)[源代码]
Executes a request, returning an HTTPResponse.
The request may be either a string URL or an HTTPRequest object.
If it is a string, we construct an HTTPRequest using any additional
kwargs: HTTPRequest(request, **kwargs)
If an error occurs during the fetch, we raise an HTTPError.
-
class tornado.httpclient.AsyncHTTPClient[源代码]
An non-blocking HTTP client.
Example usage:
def handle_request(response):
if response.error:
print "Error:", response.error
else:
print response.body
http_client = AsyncHTTPClient()
http_client.fetch("http://www.google.com/", handle_request)
The constructor for this class is magic in several respects: It
actually creates an instance of an implementation-specific
subclass, and instances are reused as a kind of pseudo-singleton
(one per IOLoop). The keyword argument force_instance=True
can be used to suppress this singleton behavior. Constructor
arguments other than io_loop and force_instance are
deprecated. The implementation subclass as well as arguments to
its constructor can be set with the static method configure()
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close()[源代码]
Destroys this HTTP client, freeing any file descriptors used.
Not needed in normal use, but may be helpful in unittests that
create and destroy http clients. No other methods may be called
on the AsyncHTTPClient after close().
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fetch(request, callback=None, **kwargs)[源代码]
Executes a request, asynchronously returning an HTTPResponse.
The request may be either a string URL or an HTTPRequest object.
If it is a string, we construct an HTTPRequest using any additional
kwargs: HTTPRequest(request, **kwargs)
This method returns a Future whose result is an
HTTPResponse. The Future wil raise an HTTPError if
the request returned a non-200 response code.
If a callback is given, it will be invoked with the HTTPResponse.
In the callback interface, HTTPError is not automatically raised.
Instead, you must check the response’s error attribute or
call its rethrow method.
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classmethod configure(impl, **kwargs)[源代码]
Configures the AsyncHTTPClient subclass to use.
AsyncHTTPClient() actually creates an instance of a subclass.
This method may be called with either a class object or the
fully-qualified name of such a class (or None to use the default,
SimpleAsyncHTTPClient)
If additional keyword arguments are given, they will be passed
to the constructor of each subclass instance created. The
keyword argument max_clients determines the maximum number
of simultaneous fetch() operations that can
execute in parallel on each IOLoop. Additional arguments
may be supported depending on the implementation class in use.
Example:
AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
Request 对象
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class tornado.httpclient.HTTPRequest(url, method='GET', headers=None, body=None, auth_username=None, auth_password=None, auth_mode=None, connect_timeout=None, request_timeout=None, if_modified_since=None, follow_redirects=None, max_redirects=None, user_agent=None, use_gzip=None, network_interface=None, streaming_callback=None, header_callback=None, prepare_curl_callback=None, proxy_host=None, proxy_port=None, proxy_username=None, proxy_password=None, allow_nonstandard_methods=None, validate_cert=None, ca_certs=None, allow_ipv6=None, client_key=None, client_cert=None)[源代码]
HTTP client request object.
All parameters except url are optional.
参数: |
- url (string) – URL to fetch
- method (string) – HTTP method, e.g. “GET” or “POST”
- headers (HTTPHeaders or dict) – Additional HTTP headers to pass on the request
- body – HTTP body to pass on the request
- auth_username (string) – Username for HTTP authentication
- auth_password (string) – Password for HTTP authentication
- auth_mode (string) – Authentication mode; default is “basic”.
Allowed values are implementation-defined; curl_httpclient
supports “basic” and “digest”; simple_httpclient only supports
“basic”
- connect_timeout (float) – Timeout for initial connection in seconds
- request_timeout (float) – Timeout for entire request in seconds
- if_modified_since (datetime or float) – Timestamp for If-Modified-Since header
- follow_redirects (bool) – Should redirects be followed automatically
or return the 3xx response?
- max_redirects (int) – Limit for follow_redirects
- user_agent (string) – String to send as User-Agent header
- use_gzip (bool) – Request gzip encoding from the server
- network_interface (string) – Network interface to use for request
- streaming_callback (callable) – If set, streaming_callback will
be run with each chunk of data as it is received, and
HTTPResponse.body and HTTPResponse.buffer will be empty in
the final response.
- header_callback (callable) – If set, header_callback will
be run with each header line as it is received (including the
first line, e.g. HTTP/1.0 200 OK\r\n, and a final line
containing only \r\n. All lines include the trailing newline
characters). HTTPResponse.headers will be empty in the final
response. This is most useful in conjunction with
streaming_callback, because it’s the only way to get access to
header data while the request is in progress.
- prepare_curl_callback (callable) – If set, will be called with
a pycurl.Curl object to allow the application to make additional
setopt calls.
- proxy_host (string) – HTTP proxy hostname. To use proxies,
proxy_host and proxy_port must be set; proxy_username and
proxy_pass are optional. Proxies are currently only supported
with curl_httpclient.
- proxy_port (int) – HTTP proxy port
- proxy_username (string) – HTTP proxy username
- proxy_password (string) – HTTP proxy password
- allow_nonstandard_methods (bool) – Allow unknown values for method
argument?
- validate_cert (bool) – For HTTPS requests, validate the server’s
certificate?
- ca_certs (string) – filename of CA certificates in PEM format,
or None to use defaults. Note that in curl_httpclient, if
any request uses a custom ca_certs file, they all must (they
don’t have to all use the same ca_certs, but it’s not possible
to mix requests with ca_certs and requests that use the defaults.
- allow_ipv6 (bool) – Use IPv6 when available? Default is false in
simple_httpclient and true in curl_httpclient
- client_key (string) – Filename for client SSL key, if any
- client_cert (string) – Filename for client SSL certificate, if any
|
3.1 新版功能: The auth_mode argument.
Response 对象
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class tornado.httpclient.HTTPResponse(request, code, headers=None, buffer=None, effective_url=None, error=None, request_time=None, time_info=None, reason=None)[源代码]
HTTP Response object.
Attributes:
- request: HTTPRequest object
- code: numeric HTTP status code, e.g. 200 or 404
- reason: human-readable reason phrase describing the status code
(with curl_httpclient, this is a default value rather than the
server’s actual response)
- headers: tornado.httputil.HTTPHeaders object
- buffer: cStringIO object for response body
- body: response body as string (created on demand from self.buffer)
- error: Exception object, if any
- request_time: seconds from request start to finish
- time_info: dictionary of diagnostic timing information from the request.
Available data are subject to change, but currently uses timings
available from http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html,
plus queue, which is the delay (if any) introduced by waiting for
a slot under AsyncHTTPClient‘s max_clients setting.
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rethrow()[源代码]
If there was an error on the request, raise an HTTPError.
Exceptions
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exception tornado.httpclient.HTTPError(code, message=None, response=None)[源代码]
Exception thrown for an unsuccessful HTTP request.
Attributes:
- code - HTTP error integer error code, e.g. 404. Error code 599 is
used when no HTTP response was received, e.g. for a timeout.
- response - HTTPResponse object, if any.
Note that if follow_redirects is False, redirects become HTTPErrors,
and you can look at error.response.headers['Location'] to see the
destination of the redirect.
命令行接口
该模块使用 Tornado HTTP 客户端实现了一个简单的命令行请求 URL 的接口。示例: