nodejs调用delphi编写的dll

公司的业务须要，nodejs要读取文件版本号。

同事要求我用delphi编写dll，以供nodejs调用，结果经过json返回。

delphi代码以下：

 1 function GetFileInfo(APath: PAnsiChar): PAnsiChar;  2 var
 3   sPath: string;  4  FInfoSize, Temp, Len: Cardinal;  5  InfoBuf: Pointer;  6  TranslationLength: Cardinal;  7  TranslationTable: Pointer;  8  LanguageID, CodePage, LookupString: String;  9  Value: PChar; 10  vJ: ISuperObject; 11 begin
12   sPath := Utf8ToAnsi(strPas(APath)); 13   FInfoSize := GetFileVersionInfoSize(PChar(sPath), Temp); 14   vJ := SO; 15   if FInfoSize > 0 then
16   begin
17     InfoBuf := AllocMem(FInfoSize); 18     try  // try
19       GetFileVersionInfo(PChar(sPath), 0, FInfoSize, InfoBuf); 20 
21       if VerQueryValue( InfoBuf, '\VarFileInfo\Translation', TranslationTable, TranslationLength ) then
22       begin
23         CodePage := Format( '%.4x', [ HiWord( PLongInt( TranslationTable )^ ) ] ); 24         LanguageID := Format( '%.4x', [ LoWord( PLongInt( TranslationTable )^ ) ] ); 25       end; 26       LookupString := 'StringFileInfo\' + LanguageID + CodePage + '\'; 27 
28       if VerQueryValue( InfoBuf, PChar( LookupString + 'CompanyName' ), Pointer( Value ), Len ) then
29         vJ.S['CompanyName'] := Value; 30       if VerQueryValue( InfoBuf, PChar( LookupString + 'FileDescription' ), Pointer( Value ), Len ) then
31         vJ.S['FileDescription'] := Value; 32       if VerQueryValue( InfoBuf, PChar( LookupString + 'FileVersion' ), Pointer( Value ), Len ) then
33         vJ.S['FileVersion'] := Value; 34       if VerQueryValue( InfoBuf, PChar( LookupString + 'InternalName' ), Pointer( Value ), Len ) then
35         vJ.S['InternalName'] := Value; 36       if VerQueryValue( InfoBuf, PChar( LookupString + 'LegalCopyright' ), Pointer( Value ), Len ) then
37         vJ.S['LegalCopyright'] := Value; 38       if VerQueryValue( InfoBuf, PChar( LookupString + 'LegalTrademarks' ), Pointer( Value ), Len ) then
39         vJ.S['LegalTrademarks'] := Value; 40       if VerQueryValue( InfoBuf, PChar( LookupString + 'OriginalFilename' ), Pointer( Value ), Len ) then
41         vJ.S['OriginalFilename'] := Value; 42       if VerQueryValue( InfoBuf, PChar( LookupString + 'ProductName' ), Pointer( Value ), Len ) then
43         vJ.S['ProductName'] := Value; 44       if VerQueryValue( InfoBuf, PChar( LookupString + 'ProductVersion' ), Pointer( Value ), Len ) then
45         vJ.S['ProductVersion'] := Value; 46       if VerQueryValue( InfoBuf, PChar( LookupString + 'Comments' ), Pointer( Value ), Len ) then
47         vJ.S['Comments'] := Value; 48     finally  // wrap up finally
49  FreeMem(InfoBuf, FInfoSize); 50     end;  // end try finally
51   end; 52   Result := PAnsiChar(AnsiString(vJ.AsJSon)); 53 end;

PS：

1. 用到的字符串可能较长，注意调用ShareMem

2. 全部的string类型都须要定义成PAnsiChar

3. 此处nodejs使用的编码是utf8，须要转码

4. 返回值，需先经过AnsiString转换，再转换PAnsiChar，否则只能读取到第一个字符

 

nodejs测试代码以下：

 1 var ffi = require('ffi');  2 
 3 try {  4     var demo = ffi.Library('./fileInfo', {  5         'GetFileInfo': [ 'string', ['string'] ],  6  });  7 
 8  console.log(demo);  9     const info = demo.GetFileInfo('C:\\Program Files (x86)\\Tencent\\WeChat\\WeChat.exe');
10  console.log(JSON.parse(info)); 11     console.log('End Test'); 12 } catch(err) { 13  console.log(err); 14 }

测试结果以下：