Delphi Url编码和解码

TIdURI类中有两个用于对URL进行编码/解码的静态方法

 uses
   IdURI;

..
begin
   S := TIdURI.URLEncode(str);
//
   S := TIdURI.URLDecode(str);
end;

在Delphi新版中，使用TNetEncoding.URL.Decode

 Uses
   NetEncoding;

function URLEncode(const s : string) : string;
begin
   result := TNetEncoding.URL.Encode(s);
end

TIdUri或HTTPEncode的Unicode字符集有问题。以下功能将为您正确编码。

 function EncodeURIComponent(const ASrc: string): UTF8String;
const
  HexMap: UTF8String = '0123456789ABCDEF';

  function IsSafeChar(ch: Integer): Boolean;
  begin
    if (ch >= 48) and (ch <= 57) then Result := True    // 0-9
    else if (ch >= 65) and (ch <= 90) then Result := True  // A-Z
    else if (ch >= 97) and (ch <= 122) then Result := True  // a-z
    else if (ch = 33) then Result := True // !
    else if (ch >= 39) and (ch <= 42) then Result := True // '()*
    else if (ch >= 45) and (ch <= 46) then Result := True // -.
    else if (ch = 95) then Result := True // _
    else if (ch = 126) then Result := True // ~
    else Result := False;
  end;
var
  I, J: Integer;
  ASrcUTF8: UTF8String;
begin
  Result := '';    {Do not Localize}

  ASrcUTF8 := UTF8Encode(ASrc);
  // UTF8Encode call not strictly necessary but
  // prevents implicit conversion warning

  I := 1; J := 1;
  SetLength(Result, Length(ASrcUTF8) * 3); // space to %xx encode every byte
  while I <= Length(ASrcUTF8) do
  begin
    if IsSafeChar(Ord(ASrcUTF8[I])) then
    begin
      Result[J] := ASrcUTF8[I];
      Inc(J);
    end
    else if ASrcUTF8[I] = ' ' then
    begin
      Result[J] := '+';
      Inc(J);
    end
    else
    begin
      Result[J] := '%';
      Result[J+1] := HexMap[(Ord(ASrcUTF8[I]) shr 4) + 1];
      Result[J+2] := HexMap[(Ord(ASrcUTF8[I]) and 15) + 1];
      Inc(J,3);
    end;
    Inc(I);
  end;

  SetLength(Result, J-1);
end;