中心类在 email 包是 消息 类，导入自 email.message 模块。它是基类对于 email 对象模型。 消息 provides the core functionality for setting and querying header fields, and for accessing message bodies.
Conceptually, a 消息 object consists of headers and payloads . Headers are RFC 2822 style field names and values where the field name and value are separated by a colon. The colon is not part of either the field name or the field value.
Headers are stored and returned in case-preserving form but are matched case-insensitively. There may also be a single envelope header, also known as the Unix-From header or the From_ header. The payload is either a string in the case of simple message objects or a list of 消息 objects for MIME container documents (e.g. multipart/* and message/rfc822 ).
消息 objects provide a mapping style interface for accessing the message headers, and an explicit interface for accessing both the headers and the payload. It provides convenience methods for generating a flat text representation of the message object tree, for accessing commonly used header parameters, and for recursively walking over the object tree.
这里是方法对于 消息 类：
The constructor takes no arguments.
返回扁平化成字符串的整个消息。当可选 unixfrom is True , the envelope header is included in the returned string. unixfrom 默认为 False . Flattening the message may trigger changes to the 消息 若默认需要填充以完成字符串转换 (例如，可以生成或修改 MIME 边界)。
Note that this method is provided as a convenience and may not always format the message the way you want. For example, by default it mangles lines that begin with 从 . For more flexibility, instantiate a 生成器 instance and use its flatten() method directly. For example:
from cStringIO import StringIO from email.generator import Generator fp = StringIO() g = Generator(fp, mangle_from_=False, maxheaderlen=60) g.flatten(msg) text = fp.getvalue()
相当于 as_string(unixfrom=True) .
返回 True 若消息负载是列表对于子 消息 对象，否则返回 False 。当 is_multipart() 返回 False , the payload should be a string object.
将消息的信封头设为 unixfrom ，其应该是字符串。
返回消息的信封头。默认为 None 若从未设置信封头。
添加给定 payload 到当前负载，其必须是 None 或列表化的 消息 对象在调用之前。在调用后，负载将始终是列表对于 消息 对象。若想要将负载设为标量对象 (如：字符串)，使用 set_payload() 代替。
返回当前负载，其是列表对于 消息 对象当 is_multipart() is True ，或字符串当 is_multipart() is False . If the payload is a list and you mutate the list object, you modify the message’s payload in place.
采用可选自变量 i , get_payload() 将返回 i -th element of the payload, counting from zero, if is_multipart() is True . An IndexError 会被引发若 i is less than 0 or greater than or equal to the number of items in the payload. If the payload is a string (i.e. is_multipart() is False ) 和 i is given, a TypeError 被引发。
可选 decode is a flag indicating whether the payload should be decoded or not, according to the Content-Transfer-Encoding header. When True and the message is not a multipart, the payload will be decoded if this header’s value is quoted-printable or base64 . If some other encoding is used, or Content-Transfer-Encoding header is missing, or if the payload has bogus base64 data, the payload is returned as-is (undecoded). If the message is a multipart and the decode flag is True ，那么 None is returned. The default for decode is False .
Set the entire message object’s payload to payload . It is the client’s responsibility to ensure the payload invariants. Optional charset sets the message’s default character set; see set_charset() 了解细节。
Changed in version 2.2.2: charset argument added.
Set the character set of the payload to charset , which can either be a Charset 实例 (见 email.charset ), a string naming a character set, or None . If it is a string, it will be converted to a Charset instance. If charset is None ， charset parameter will be removed from the Content-Type header (the message will not be otherwise modified). Anything else will generate a TypeError .
If there is no existing MIME-Version header one will be added. If there is no existing Content-Type header, one will be added with a value of text/plain . Whether the Content-Type header already exists or not, its charset parameter will be set to charset.output_charset 。若 charset.input_charset and charset.output_charset differ, the payload will be re-encoded to the output_charset . If there is no existing Content-Transfer-Encoding header, then the payload will be transfer-encoded, if needed, using the specified Charset , and a header with the appropriate value will be added. If a Content-Transfer-Encoding header already exists, the payload is assumed to already be correctly encoded using that Content-Transfer-Encoding and is not modified.
The message will be assumed to be of type text/* , with the payload either in unicode or encoded with charset.input_charset . It will be encoded or converted to charset.output_charset and transfer encoded properly, if needed, when generating the plain text representation of the message. MIME headers ( MIME-Version , Content-Type , Content-Transfer-Encoding ) will be added as needed.
New in version 2.2.2.
The following methods implement a mapping-like interface for accessing the message’s RFC 2822 headers. Note that there are some semantic differences between these methods and a normal mapping (i.e. dictionary) interface. For example, in a dictionary there are no duplicate keys, but here there may be duplicate message headers. Also, in dictionaries there is no guaranteed order to the keys returned by keys() , but in a 消息 object, headers are always returned in the order they appeared in the original message, or were added to the message later. Any header deleted and then re-added are always appended to the end of the header list.
These semantic differences are intentional and are biased toward maximal convenience.
Note that in all cases, any envelope header present in the message is not included in the mapping interface.
返回 Header 头的总数，包括重复的。
Return true if the message object has a field named name . Matching is done case-insensitively and name should not include the trailing colon. Used for the in operator, e.g.:
if 'message-id' in myMessage: print 'Message-ID:', myMessage['message-id']
Return the value of the named header field. name should not include the colon field separator. If the header is missing, None is returned; a KeyError 从不被引发。
Note that if the named field appears more than once in the message’s headers, exactly which of those field values will be returned is undefined. Use the get_all() method to get the values of all the extant named headers.
将 Header 头添加到消息采用字段名称 name 和值 val . The field is appended to the end of the message’s existing fields.
Note that this does not overwrite or delete any existing header with the same name. If you want to ensure that the new header is the only one present in the message with field name name , delete the field first, e.g.:
del msg['subject'] msg['subject'] = 'Python roolz!'
Delete all occurrences of the field with name name from the message’s headers. No exception is raised if the named field isn’t present in the headers.
Return true if the message contains a header field named name , otherwise return false.
返回所有消息头字段名称的列表。
返回所有消息字段值的列表。
返回包含所有消息的字段 Header 头和值的 2 元素元组的列表。
返回命名头字段的值。这等同于 __getitem__() 除了可选 failobj 被返回若缺失命名头 (默认为 None ).
这里是一些额外有用方法：
返回所有值的列表对于字段命名 name 。若消息中没有这种命名头， failobj 被返回 (默认为 None ).
扩展 Header 头设置。此方法类似于 __setitem__() 除可以提供额外 Header 头参数作为关键词自变量外。 _name 是要添加的头字段和 _value 是 primary 头值。
For each item in the keyword argument dictionary _params , the key is taken as the parameter name, with underscores converted to dashes (since dashes are illegal in Python identifiers). Normally, the parameter will be added as key="value" unless the value is None , in which case only the key will be added. If the value contains non-ASCII characters, it must be specified as a three tuple in the format (CHARSET, LANGUAGE, VALUE) ，其中 CHARSET is a string naming the charset to be used to encode the value, LANGUAGE can usually be set to None or the empty string (see RFC 2231 了解其它可能性)，和 VALUE is the string value containing non-ASCII code points.
这里是范例：
msg.add_header('Content-Disposition', 'attachment', filename='bud.gif')
这添加的 Header 头看起来像
Content-Disposition: attachment; filename="bud.gif"
非 ASCII 字符范例：
msg.add_header('Content-Disposition', 'attachment', filename=('iso-8859-1', '', 'Fußballer.ppt'))
其产生
Content-Disposition: attachment; filename*="iso-8859-1''Fu%DFballer.ppt"
Replace a header. Replace the first header found in the message that matches _name , retaining header order and field name case. If no matching header was found, a KeyError 被引发。
New in version 2.2.2.
Return the message’s content type. The returned string is coerced to lower case of the form maintype/subtype . If there was no Content-Type header in the message the default type as given by get_default_type() will be returned. Since according to RFC 2045 , messages always have a default type, get_content_type() will always return a value.
RFC 2045 defines a message’s default type to be text/plain unless it appears inside a multipart/digest container, in which case it would be message/rfc822 。若 Content-Type header has an invalid type specification, RFC 2045 mandates that the default type be text/plain .
New in version 2.2.2.
Return the message’s main content type. This is the maintype part of the string returned by get_content_type() .
New in version 2.2.2.
Return the message’s sub-content type. This is the subtype part of the string returned by get_content_type() .
New in version 2.2.2.
Return the default content type. Most messages have a default content type of text/plain , except for messages that are subparts of multipart/digest containers. Such subparts have a default content type of message/rfc822 .
New in version 2.2.2.
Set the default content type. ctype should either be text/plain or message/rfc822 , although this is not enforced. The default content type is not stored in the Content-Type 头。
New in version 2.2.2.
Return the message’s Content-Type parameters, as a list. The elements of the returned list are 2-tuples of key/value pairs, as split on the '=' sign. The left hand side of the '=' is the key, while the right hand side is the value. If there is no '=' sign in the parameter the value is the empty string, otherwise the value is as described in get_param() and is unquoted if optional unquote is True (the default).
可选 failobj is the object to return if there is no Content-Type header. Optional header is the header to search instead of Content-Type .
Changed in version 2.2.2: unquote argument added.
Return the value of the Content-Type header’s parameter param as a string. If the message has no Content-Type header or if there is no such parameter, then failobj 被返回 (默认为 None ).
可选 header if given, specifies the message header to use instead of Content-Type .
Parameter keys are always compared case insensitively. The return value can either be a string, or a 3-tuple if the parameter was RFC 2231 encoded. When it’s a 3-tuple, the elements of the value are of the form (CHARSET, LANGUAGE, VALUE) 。注意 CHARSET and LANGUAGE 可以是 None , in which case you should consider VALUE to be encoded in the us-ascii charset. You can usually ignore LANGUAGE .
If your application doesn’t care whether the parameter was encoded as in RFC 2231 , you can collapse the parameter value by calling email.utils.collapse_rfc2231_value() , passing in the return value from get_param() . This will return a suitably decoded Unicode string when the value is a tuple, or the original string unquoted if it isn’t. For example:
rawparam = msg.get_param('foo') param = email.utils.collapse_rfc2231_value(rawparam)
In any case, the parameter value (either the returned string, or the VALUE item in the 3-tuple) is always unquoted, unless unquote 被设为 False .
Changed in version 2.2.2: unquote argument added, and 3-tuple return value possible.
Set a parameter in the Content-Type header. If the parameter already exists in the header, its value will be replaced with value 。若 Content-Type header as not yet been defined for this message, it will be set to text/plain and the new parameter value will be appended as per RFC 2045 .
可选 header specifies an alternative header to Content-Type , and all parameters will be quoted as necessary unless optional requote is False (the default is True ).
若可选 charset is specified, the parameter will be encoded according to RFC 2231 。可选 语言 specifies the RFC 2231 language, defaulting to the empty string. Both charset and 语言 should be strings.
New in version 2.2.2.
Remove the given parameter completely from the Content-Type header. The header will be re-written in place without the parameter or its value. All values will be quoted as necessary unless requote is False (the default is True ). Optional header specifies an alternative to Content-Type .
New in version 2.2.2.
Set the main type and subtype for the Content-Type 头。 type must be a string in the form maintype/subtype , otherwise a ValueError 被引发。
This method replaces the Content-Type header, keeping all the parameters in place. If requote is False , this leaves the existing header’s quoting as is, otherwise the parameters will be quoted (the default).
An alternative header can be specified in the header argument. When the Content-Type header is set a MIME-Version header is also added.
New in version 2.2.2.
Return the value of the filename 参数为 Content-Disposition header of the message. If the header does not have a filename parameter, this method falls back to looking for the name parameter on the Content-Type header. If neither is found, or the header is missing, then failobj is returned. The returned string will always be unquoted as per email.utils.unquote() .
Return the value of the boundary 参数为 Content-Type header of the message, or failobj if either the header is missing, or has no boundary parameter. The returned string will always be unquoted as per email.utils.unquote() .
设置 boundary 参数为 Content-Type header to boundary . set_boundary() will always quote boundary if necessary. A HeaderParseError is raised if the message object has no Content-Type 头。
Note that using this method is subtly different than deleting the old Content-Type header and adding a new one with the new boundary via add_header() ，因为 set_boundary() preserves the order of the Content-Type header in the list of headers. However, it does not preserve any continuation lines which may have been present in the original Content-Type 头。
返回 charset 参数为 Content-Type header, coerced to lower case. If there is no Content-Type header, or if that header has no charset 参数， failobj 被返回。
Note that this method differs from get_charset() which returns the Charset instance for the default encoding of the message body.
New in version 2.2.2.
Return a list containing the character set names in the message. If the message is a multipart , then the list will contain one element for each subpart in the payload, otherwise, it will be a list of length 1.
Each item in the list will be a string which is the value of the charset parameter in the Content-Type header for the represented subpart. However, if the subpart has no Content-Type header, no charset parameter, or is not of the text main MIME type, then that item in the returned list will be failobj .
The walk() method is an all-purpose generator which can be used to iterate over all the parts and subparts of a message object tree, in depth-first traversal order. You will typically use walk() as the iterator in a for loop; each iteration returns the next subpart.
Here’s an example that prints the MIME type of every part of a multipart message structure:
>>> for part in msg.walk(): ... print part.get_content_type() multipart/report text/plain message/delivery-status text/plain text/plain message/rfc822
Changed in version 2.5: The previously deprecated methods get_type() , get_main_type() ，和 get_subtype() were removed.
消息 objects can also optionally contain two instance attributes, which can be used when generating the plain text of a MIME message.
The format of a MIME document allows for some text between the blank line following the headers, and the first multipart boundary string. Normally, this text is never visible in a MIME-aware mail reader because it falls outside the standard MIME armor. However, when viewing the raw text of the message, or when viewing the message in a non-MIME aware reader, this text can become visible.
The preamble attribute contains this leading extra-armor text for MIME documents. When the Parser discovers some text after the headers but before the first boundary string, it assigns this text to the message’s preamble attribute. When the 生成器 is writing out the plain text representation of a MIME message, and it finds the message has a preamble attribute, it will write this text in the area between the headers and the first boundary. See email.parser and email.generator 了解细节。
Note that if the message object has no preamble, the preamble 属性将是 None .
The epilogue attribute acts the same way as the preamble attribute, except that it contains text that appears between the last boundary and the end of the message.
Changed in version 2.5: You do not need to set the epilogue to the empty string in order for the 生成器 to print a newline at the end of the file.
The defects attribute contains a list of all the problems found when parsing this message. See email.errors for a detailed description of the possible parsing defects.
2.4 版新增。
