python zlib ，zlib 压缩流

zlib
字符串：使用zlib.compress可以压缩字符串。使用zlib.decompress可以解压字符串。
数据流：压缩：compressobj，解压：decompressobj
 
 
 

import zlib
import time

s='aldsfjdals拉萨的附近拉水电费拉克丝等级分sdfgfsdgsdfg ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd类的撒酒疯拉萨的解放路'.encode('utf-8')
#需要转成bytes类型:
for i in range(0,15):
    s+=s
print(len(s))

#---------------------------------------------------
str_time=time.time()
compress_str  = zlib.compress(s)#进行压缩
print(len(compress_str))
#print(zlib.decompress(compress_str).decode('utf-8'))#数据解压
print(time.time()-str_time)

#-------------------------------------------------
str_obj=time.time()
level=9
c_obj = zlib.compressobj(level)#设置压缩等级
com_obj_str = c_obj.compress(s)
print(len(com_obj_str))
print(time.time()-str_obj)

# 7995392
# 31149
# 0.12890625
# 16425
# 0.1015625

 注：compressobj返回一个压缩对象，用来压缩不能一下子读入内存的数据流。 level 从9到-1表示压缩等级，其中1最快但压缩度最小，9最慢但压缩度最大，0不压缩，默认是-1大约相当于与等级6，是一个压缩速度和压缩度适中的level。

压缩内存中的二进制流

from io import BytesIO

import zlib

b_memory= BytesIO()

b_memory.write("很多数据sldkfjlsakjfsldakjflasjflaskdj".encode('utf-8'))

compress_str = zlib.compress(b_memory.getvalue())

print(compress_str)

print(zlib.decompress(compress_str).decode('utf-8'))

 

数据流压缩和实际应用  

from io import BytesIOimport xlsxwriter as xwimport zlibbytesio = BytesIO()workbook = xw.Workbook(bytesio)

work_sheet = workbook.add_worksheet('excel')merge_format=workbook.add_format(    {        "bold":True,        "bg_color":"red",        "valign":"top"    })for row in range(10):    for col in range(10):        work_sheet.write(row,col,"需要写入的内容",merge_format)

workbook.close()

file_bytes = bytesio.getvalue()print("文件大小:{}".format(len(file_bytes)))with open('save.xlsx','wb') as f:    f.write(file_bytes)    f.flush()

compress_file_bytes = zlib.compress(file_bytes,9)print("文件大小:{}".format(len(compress_file_bytes)))