HTTP头部POST表单详解

 2 POST /hello/checkUser.html?opt=xxx HTTP/1.1           方法的声明，Get，Post，Delete等
 3 Accept: */*
 4 Referer: http://localhost:8000/hello/index.html       表示是从什么地方跳转过来的，有时候做爬虫的时候会用到，有些网站用这个字段来防止被爬虫
 5 Accept-Language: zh-cn
 6 Content-Type: multipart/form-data; boundary=---------------------------7d931c5d043e     表示本次传输数据的类型，form-data表示表单数据，其中boundary表示后面body的分隔符
 7 Accept-Encoding: gzip, deflate
 8 Host: localhost:8000
 9 Content-Length: 382
10 Connection: Keep-Alive
11 Cache-Control: no-cache
12 Cookie: JSESSIONID=6FE3D8E365DF9FE26221A32624470D24
13 -----------------------------7d931c5d043e
14 Content-Disposition: form-data; name="username"
15 yyy
16 -----------------------------7d931c5d043e
17 Content-Disposition: form-data; name="age"
18 zzz
19 -----------------------------7d931c5d043e
20 Content-Disposition: form-data; name="file"; filename="C:\1.txt"
21 Content-Type: text/plain
22 hello
23 -----------------------------7d931c5d043e--