如何从lua发送给NodeMCU的http请求中获取post参数 [英] How to get post parameters from http request in lua sent to NodeMCU

问题描述

我通过Tasker（Android应用程序）将此HTTP POST请求发送到我的NodeMCU，如下所示：

I sent this HTTP POST request via Tasker (Android app) to my NodeMCU, which looks like this:

POST / HTTP/1.1
Content-Type: application/x-www-form-urlencoded
User-Agent: Tasker/4.9u4m (Android/6.0.1)
Connection: close
Content-Length: 10
Host: 192.168.0.22
Accept-Encoding: gzip

<action>Play</action><SetVolume>5</SetVolume>

我只想提取< action>之间的内容和< SetVolume>参数。我该怎么做？

I only want to extract what is between the "<action>" and "<SetVolume>" parameters. How can I do that?

推荐答案

此函数允许您从两个字符串分隔符之间提取文本：

This function allows you to extract text from between two string delimiters:

function get_text (str, init, term)
   local _, start = string.find(str, init)
   local stop = string.find(str, term)
   local result = nil
   if _ and stop then
      result = string.sub(str, start + 1, stop - 1)
   end
   return result
end

示例交互：

> msg = "<action>Play</action><SetVolume>5</SetVolume>"
> get_text(msg, "<action>", "<SetVolume>")
Play</action>
> get_text(msg, "<action>", "</SetVolume>")
Play</action><SetVolume>5

这是对上述函数的修改，允许 nil 用于任一参数 init 或 term 。如果 init 是 nil ，则文本将被提取到 term 分隔符。如果 term 是 nil ，则在 init 到字符串的结尾。

This is a modification of the above function that allows nil for either of the parameters init or term. If init is nil, then text is extracted up to the term delimiter. If term is nil, then text is extracted from after init to the end of the string.

function get_text (str, init, term)
   local _, start
   local stop = (term and string.find(str, term)) or 0
   local result = nil
   if init then
      _, start = string.find(str, init)
   else
      _, start = 1, 0
   end

   if _ and stop then
      result = string.sub(str, start + 1, stop - 1)
   end
   return result
end

示例互动：

> msg = "<action>Play</action><SetVolume>5</SetVolume>"
> get_text(msg)
<action>Play</action><SetVolume>5</SetVolume>
> get_text(msg, nil, '<SetVolume>')
<action>Play</action>
> get_text(msg, '</action>')
<SetVolume>5</SetVolume>
> get_text(msg, '<action>', '<SetVolume>')
Play</action>

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