Python网络编程实践代码.zip

[Return to the Table of Contents](https://github.com/brandon-rhodes/fopnp#readme) # Chapter 12<br>Building and Parsing E-Mail This is a directory of program listings from Chapter 12 of the book: <dl> <dt><i>Foundations of Python Network Programming</i></dt> <dd> Third Edition, October 2014<br> by Brandon Rhodes and John Goerzen </dd> </dl> You can learn more about the book by visiting the [root of this GitHub source code repository](https://github.com/brandon-rhodes/fopnp#readme). The scripts in this chapter work only in Python 3.4 and later, because they take advantage of several innovations in the Standard Library `email` module that have been recently introduced by R. David Murray. If you are stuck on an older version of Python 3 then you will want to visit the [`pre-python-3.4`](https://github.com/brandon-rhodes/fopnp/tree/m/py3/chapter12/pre-python-3.4) subdirectory, where you can find the examples from the Second Edition of the book updated for Python 3. The original Python 2 examples are in the [`py2/chapter12`](https://github.com/brandon-rhodes/fopnp/tree/m/py2/chapter12) directory of this source code repository. The simplest script builds an email message, which the book takes as a basic example of what email looks like on the wire or when saved in a raw form to disk by a mail spool or client. ``` $ python3 build_basic_email.py > mail.txt ``` ``` $ cat mail.txt To: recipient@example.com From: Test Sender <sender@example.com> Subject: Test Message, Chapter 12 Date: Tue, 25 Mar 2014 19:20:08 -0400 Message-ID: <20140325232008.15748.50494@guinness> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit MIME-Version: 1.0 Hello, This is a basic message from Chapter 12. - Anonymous ``` An email client will typically hide most of these details from the user. The `display_email.py` script is offered as an example of the kind of information that the user might want to see when they view a message. ``` $ python3 display_email.py < mail.txt From: Test Sender <sender@example.com> To: recipient@example.com Date: Tue, 25 Mar 2014 19:20:08 -0400 Subject: Test Message, Chapter 12 Hello, This is a basic message from Chapter 12. - Anonymous ``` From these simple beginnings, the book progresses through more and more complicated examples of MIME encoding until it has explained alternative parts, related parts, and attachments. All of these features can be seen interacting in a single message by giving `build_mime_email.py` exactly the right arguments: ``` $ python3 build_mime_email.py -i attachment.txt attachment.gz > mail.txt ``` ``` $ cat mail.txt To: Test Recipient <recipient@example.com> From: Test Sender <sender@example.com> Subject: Foundations of Python Network Programming Date: Tue, 25 Mar 2014 19:20:08 -0400 Message-ID: <20140325232008.15748.50494@guinness> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0086939546==" --===============0086939546== Content-Type: multipart/alternative; boundary="===============0903170602==" --===============0903170602== Content-Type: multipart/related; boundary="===============1911784257==" --===============1911784257== Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: 7bit <p>Hello,</p> <p>This is a <b>test message</b> from Chapter 12.</p> <p>- <i>Anonymous</i></p><p>This is the smallest possible blue GIF:</p> <img src="cid:20140325232008.15748.99346@guinness" height="80" width="80"> --===============1911784257== Content-Type: image/gif Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="blue-dot.gif" Content-ID: <20140325232008.15748.99346@guinness> MIME-Version: 1.0 R0lGODlhAQABAJAAAAAA/wAAACwAAAAAAQABAAACAgQBADs= --===============1911784257==-- --===============0903170602== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit MIME-Version: 1.0 Hello, This is a MIME message from Chapter 12. - Anonymous --===============0903170602==-- --===============0086939546== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="attachment.txt" MIME-Version: 1.0 This is a test --===============0086939546== Content-Type: application/octet-stream Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="attachment.gz" MIME-Version: 1.0 H4sIAP3o2D8AAwvJyCxWAKJEhZLU4hIuAIwtwPoPAAAA --===============0086939546==-- ``` The book then shows how this complexity is hidden from a typical email user by invoking both the `display_email.py` script and also the more low-level investigative `display_structure.py` script to look at the email’s structure in fine details. These scripts can also be used to unravel complicated real-world emails from the reader’s own mailbox. ``` $ python3 display_email.py < mail.txt From: Test Sender <sender@example.com> To: Test Recipient <recipient@example.com> Date: Tue, 25 Mar 2014 19:20:08 -0400 Subject: Foundations of Python Network Programming Hello, This is a MIME message from Chapter 12. - Anonymous * image/gif attachment named 'blue-dot.gif': bytes object of length 35 * text/plain attachment named 'attachment.txt': str object of length 15 * application/octet-stream attachment named 'attachment.gz': bytes object of length 33 ``` ``` $ python3 display_structure.py < mail.txt type=multipart/mixed .0 type=multipart/alternative .0.0 type=multipart/related .0.0.0 type=text/html str len=215 .0.0.1 type=image/gif bytes len=35 attachment filename='blue-dot.gif' .0.1 type=text/plain str len=59 .1 type=text/plain str len=15 attachment filename='attachment.txt' .2 type=application/octet-stream bytes len=33 attachment filename='attachment.gz' ``` Finally, one last script lets the reader learn about how Unicode comes into play when it appears in email headers and when it appears in the body of an email. Encoding is necessary in both cases, because neither context traditionally allows anything except plain ASCII printable characters. ``` $ python3 build_unicode_email.py > mail.txt ``` ``` $ cat mail.txt To: =?utf-8?b?QsO2w7B2YXJy?= <recipient@example.com> From: Eardstapa <sender@example.com> Subject: Four lines from The Wanderer Date: Tue, 25 Mar 2014 19:20:08 -0400 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Hw=C3=A6r cwom mearg? Hw=C3=A6r cwom mago? Hw=C3=A6r cwom ma=C3=BE=C3=BEumgyfa? Hw=C3=A6r cwom symbla gesetu? Hw=C3=A6r sindon seledreamas? ``` ``` $ python3 display_email.py < mail.txt From: Eardstapa <sender@example.com> To: Böðvarr <recipient@example.com> Date: Tue, 25 Mar 2014 19:20:08 -0400 Subject: Four lines from The Wanderer Hwær cwom mearg? Hwær cwom mago? Hwær cwom maþþumgyfa? Hwær cwom symbla gesetu? Hwær sindon seledreamas? ``` Consult the book chapter for all of the concepts and rules behind these examples, as well as for further information about the options with which you can invoke them.