转载一段python代码，通过urllib2使用multipart/form-data来发送文件

import httplib, mimetypesdef post_multipart(host, selector, fields, files):    """    Post fields and files to an http host as multipart/form-data.    fields is a sequence of (name, value) elements for regular form fields.    files is a sequence of (name, filename, value) elements for data to be uploaded as files    Return the server's response page.    """    content_type, body = encode_multipart_formdata(fields, files)    h = httplib.HTTP(host)    h.putrequest('POST', selector)    h.putheader('content-type', content_type)    h.putheader('content-length', str(len(body)))    h.endheaders()    h.send(body)    errcode, errmsg, headers = h.getreply()    return h.file.read()def encode_multipart_formdata(fields, files):    """    fields is a sequence of (name, value) elements for regular form fields.    files is a sequence of (name, filename, value) elements for data to be uploaded as files    Return (content_type, body) ready for httplib.HTTP instance    """    BOUNDARY = '----------ThIs_Is_tHe_bouNdaRY_$'    CRLF = '\r\n'    L = []    for (key, value) in fields:        L.append('--' + BOUNDARY)        L.append('Content-Disposition: form-data; name="%s"' % key)        L.append('')        L.append(value)    for (key, filename, value) in files:        L.append('--' + BOUNDARY)        L.append('Content-Disposition: form-data; name="%s"; filename="%s"' % (key, filename))        L.append('Content-Type: %s' % get_content_type(filename))        L.append('')        L.append(value)    L.append('--' + BOUNDARY + '--')    L.append('')    body = CRLF.join(L)    content_type = 'multipart/form-data; boundary=%s' % BOUNDARY    return content_type, bodydef get_content_type(filename):    return mimetypes.guess_type(filename)[0] or 'application/octet-stream'

建议将httplib.HTTP更换为httplib.HTTPConnection，这样一来就能在httplib.Connection初始化的时候传入一个timeout，以实现更灵活的控制。

参阅：