方式一：
import requests
url="https://httpbin.org/post"
body='<?xml version=“1.0” encoding = “UTF-8”?>'\
     '<COM>'\
     '<REQ name="北京-宏哥">'\
     '<USER_ID>bjhongge</USER_ID>'\
     '<COMMODITY_ID>123456</COMMODITY_ID>'\
     '<SESSION_ID>absbnmasbnfmasbm1213</SESSION_ID>'\
     '</REQ>'\
     '</COM>'
a=requests.post(url,data=body.encode("utf-8"))
print(a.text)


方式二：
读取.xml文件的内容；

#encoding='utf-8
import requests
url="https://httpbin.org/post"
r=open('bodytext.xml').read()
#print(r)
a=requests.post(url,data=r.encode("utf-8"))
print(a.text)