flask-compress的使用方法

Posted 2020-09-28 沧海一粟，何以久远

参考：https://github.com/shengulong/flask-compress

 1、Content-Encoding是HTTP协议的响应报文头，一般形式如：Content-Encoding：gzip,deflate,compress
　　 deflate(RFC1951):一种压缩算法，使用LZ77和哈弗曼进行编码； 
　　 zlib(RFC1950):一种格式，是对deflate进行了简单的封装； 
　　 gzip(RFC1952):一种格式，也是对deflate进行的封装.

　　 可以看出deflate是最核心的算法，而zlib和gzip格式的区别仅仅是头部和尾部不一样，而实际的内容都是deflate编码的，即：
　　 gzip = gzip头(10字节) + deflate编码的实际内容 + gzip尾(8字节)
　　 zlib = zlib头 + deflate编码的实际内容 + zlib尾

2、flask-compress是用来压缩响应内容的，当然更好的解决方案是使用nginx做代理，使用nginx的自动压缩静态文件压缩功能，需要对nginx进行配置

     工作原理：flask-compress会给http响应增加两个http头：vary、content-encoding,并压缩响应的数据。

How it works

Flask-Compress both adds the various headers required for a compressed response and gzips the response data. This makes serving gzip compressed static files extremely easy.

Internally, every time a request is made the extension will check if it matches one of the compressible MIME types and will automatically attach the appropriate headers.

3、安装 pip install flask-compress

　or, if you want the latest github version:

$ pip install git+git://github.com/libwilliam/flask-compress.gi

4、使用

1 from flask import Flask
2 from flask_compress import Compress
3 
4 app = Flask(__name__)
5 Compress(app)

1 from flask import Flask
2 from flask_compress import Compress
3 
4 compress = Compress()
5 
6 def start_app():
7     app = Flask(__name__)
8     compress.init_app(app)
9     return app

5、选项

Within your Flask application\'s settings you can provide the following settings to control the behavior of Flask-Compress. None of the settings are required.

 

Option	Description	Default
COMPRESS_MIMETYPES	Set the list of mimetypes to compress here.	[ \'text/html\', \'text/css\', \'text/xml\', \'application/json\', \'application/javascript\' ]
COMPRESS_LEVEL	Specifies the gzip compression level.	6
COMPRESS_MIN_SIZE	Specifies the minimum file size threshold for compressing files.	500
COMPRESS_CACHE_KEY	Specifies the cache key method for lookup/storage of response data.	None
COMPRESS_CACHE_BACKEND	Specified the backend for storing the cached response data.	None
COMPRESS_REGISTER	Specifies if compression should be automatically registered.	True

6、示例：

 

7、说下http头Vary的作用：指定Vary: Accept-Encoding标头可告诉代理服务器缓存两种版本的资源：压缩和非压缩，这有助于避免一些公共代理不能正确地检测Content-Encoding标头的问题

参考：1、http://blog.csdn.net/fupengyao/article/details/50915526

2、http://www.webkaka.com/blog/archives/how-to-set-Vary-Accept-Encoding-header.html

8、nginx配置gzip压缩

      默认情况下，Nginx的gzip压缩是关闭的，也只对只对text/html进行压缩，需要在编辑nginx.conf文件，在http段加入一下配置，常用配置片段如下：

      gzip    on;
      gzip_comp_level  6;    # 压缩比例，比例越大，压缩时间越长。默认是1
      gzip_types    text/xml text/plain text/css application/javascript application/x-javascript application/rss+xml;     # 哪些文件可以被压缩
      gzip_disable    "MSIE [1-6]\\.";     # IE6无效

9、http的vary头在nginx中的配置方法

gzip_vary on