如何从Lua中的字符串中获取特定文本？

我想提取从HTTP请求收到的POST参数，该请求发送给我的NodeMCU。我怎样才能做到这一点？我正在考虑C＃中的以下代码。如何在Lua中实现这个？如何从Lua中的字符串中获取特定文本？

我在C＃代码：

// Response = "<action>Play</action><speed>1</speed><blah>lol</blah>" 
// ValuetoSearch = "action" 
public static string GetInformationFromResponse(string Response, string ValueToSearch, bool RemoveHtmlCharacters = true) { 
      string returnValue = ""; 
      if (RemoveHtmlCharacters) { 
       Response = Response.Replace("<" + ValueToSearch + ">", ValueToSearch); 
       Response = Response.Replace("</" + ValueToSearch + ">", ValueToSearch); 
       Response = Response.Replace("&lt;" + ValueToSearch + "&gt;", ValueToSearch); 
       Response = Response.Replace("&lt;/" + ValueToSearch + "&gt;", ValueToSearch); 
      } 

      // Response = "actionPlayaction<Speed>1</Speed><blah>lol</blah>" 

      int indexOfWord = Response.IndexOf(ValueToSearch); // indexOfWord = 0 
      int start = indexOfWord + ValueToSearch.Length; // start = 6 
      int end = Response.Length - indexOfWord - 1; // 47 
      int totalLength = Response.Length; // 48 
      string newPositionInfo = ""; 

      if (indexOfWord == -1) { 
       return ""; 
      } else { 
       newPositionInfo = Response.Substring(start, totalLength - start); // newPositionInfo = "Playaction<Speed>1</Speed><blah>lol</blah>" 
       indexOfWord = newPositionInfo.IndexOf(ValueToSearch); // indexOfWord = 4 
       returnValue = newPositionInfo.Substring(0, indexOfWord); // returnValue = "Play" 
       if (RemoveHtmlCharacters) { 
        returnValue = returnValue.Replace("&lt;", ""); 
        returnValue = returnValue.Replace("&gt;", ""); 
        returnValue = returnValue.Replace("&amp;", ""); 
       } 
       return returnValue; // "Play" 
      } 
     }

这段代码的用法如下： - 我想要获取“行动”一词之间的一切。 - 我有一个包含单词“action”的文本。

string largeText = "<action>Play</action><speed>1</speed><blah>blah</blah>" 
string wordToSearch = "action" 
string value1 = GetInformationFromResponse(largeText, "action"); 
string value2 = GetInformationFromResponse(largeText, "speed"); 
string value3 = GetInformationFromResponse(largeText, "blah"); 
// Value 1 = "Play" 
// Value 2 = "1" 
// Value 3 = "blah"

但是我如何在Lua（在我的NodeMCU上）完成同样的事情？

注：Lua和NodeMCU

来源

2017-02-04 Johnnybossboy

function GetInformationFromResponse(response, tag) 
    return 
     ((response:match((("<@>(.-)</@>"):gsub("@",tag))) or "") 
     :gsub("&(%w+);", {lt = "<", gt = ">", amp = "&"})) 
end 

local text = "<action>Play</action><speed>1</speed><blah>blah&amp;blah</blah>" 
local value1 = GetInformationFromResponse(text, "action"); -- "Play" 
local value2 = GetInformationFromResponse(text, "speed"); -- "1" 
local value3 = GetInformationFromResponse(text, "blah"); -- "blah&blah" 
local value4 = GetInformationFromResponse(text, "foo"); -- ""

来源

2017-02-04 19:02:28

谢谢！奇迹般有效！ – Johnnybossboy

新手在这里有一对夫妇的功能，将做到这一点：

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 

function get_tagged (str, tag) 
    local open_tag = "<" .. tag ..">" 
    local close_tag = "</" .. tag .. ">" 
    local _, start = string.find(str, open_tag) 
    local stop = string.find(str, close_tag) 
    local result = nil 
    if _ and stop then 
     result = string.sub(str, start + 1, stop - 1) 
    end 
    return result 
end

样品的相互作用：

> largeText = "<action>Play</action><speed>1</speed><blah>blah</blah>" 
> -- Using get_text() 
> print(get_text(largeText, "<action>", "</action>")) 
Play 
> -- Using get_tagged() 
> print(get_tagged(largeText, "action")) 
Play 
> print(get_tagged(largeText, "speed")) 
1 
> print(get_tagged(largeText, "blah")) 
blah 
> print(get_tagged(largeText, "oops")) 
nil

来源

2017-02-04 19:17:23

如何从Lua中的字符串中获取特定文本？

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