CoAP协议：CoAPCLI模拟CoAP客户端请求

以下截图中两部分分别是GET和POST请求的格式：

上图内容是通过虚拟机访问本地主机运行的CoAP服务，CoAP协议的默认端口为5683，这里的IP地址为本地主机的ip，通过‘ipconfig’命令可以在cmd中查询得到。

【附：CoAP协议响应码及含义】

   +------+------------------------------+-----------+ 
   | Code | Description                  | Reference |
   +------+------------------------------+-----------+
   | 2.01 | Created                      | [RFC7252] | 
   | 2.02 | Deleted                      | [RFC7252] |
   | 2.03 | Valid                        | [RFC7252] |
   | 2.04 | Changed                      | [RFC7252] |
   | 2.05 | Content                      | [RFC7252] |
   | 4.00 | Bad Request                  | [RFC7252] |
   | 4.01 | Unauthorized                 | [RFC7252] | 
   | 4.02 | Bad Option                   | [RFC7252] |
   | 4.03 | Forbidden                    | [RFC7252] | 
   | 4.04 | Not Found                    | [RFC7252] | 
   | 4.05 | Method Not Allowed           | [RFC7252] | 
   | 4.06 | Not Acceptable               | [RFC7252] | 
   | 4.12 | Precondition Failed          | [RFC7252] | 
   | 4.13 | Request Entity Too Large     | [RFC7252] |  
   | 4.15 | Unsupported Content-Format   | [RFC7252] |  
   | 5.00 | Internal Server Error        | [RFC7252] |
   | 5.01 | Not Implemented              | [RFC7252] | 
   | 5.02 | Bad Gateway                  | [RFC7252] |  
   | 5.03 | Service Unavailable          | [RFC7252] | 
   | 5.04 | Gateway Timeout              | [RFC7252] | 
   | 5.05 | Proxying Not Supported       | [RFC7252] | 
   +------+------------------------------+-----------+ 

 （响应码3.00-3.31是预留给未来使用的）