怎么自行HTTP的POST包头，需要使用json

不理解你为什么这么传 post的格式如下：

POST / HTTP/1.1

Host: www.wrox.com

User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6)

Gecko/20050225 Firefox/1.0.1

Content-Type: application/x-www-form-urlencoded

Content-Length: 40

Connection: Keep-Alive

     （----此处空一行----）

name=Professional%20Ajax&publisher=Wiley

实例：

POST /DEMOWebServices2.8/Service.asmx/CancelOrder HTTP/1.1

Host: api.efxnow.com

Content-Type: application/x-www-form-urlencoded

Content-Length: length

UserID=string&PWD=string&OrderConfirmation=string

post不支持太复杂的格式 可以考虑soap 示例如下：

POST /DEMOWebServices2.8/Service.asmx HTTP/1.1

Host: api.efxnow.com

Content-Type: application/soap+xml; charset=utf-8

Content-Length: length

<?xml version="1.0" encoding="utf-8"?>

<soap12:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">

<soap12:Body>

    <CancelOrder xmlns="https://api.efxnow.com/webservices2.3">

      <UserID>string</UserID>

      <PWD>string</PWD>

      <OrderConfirmation>string</OrderConfirmation>

    </CancelOrder>

</soap12:Body>

</soap12:Envelope>