delphi XE7 HttpEncode 编码问题

近期在做网址编码相关的工作，发现在用 XE5 编译的时候，一切正常，拿 到 XE7下 就 结果错误了。百度了下，谷歌 了下，有人提出，但是，我没有找到答案，也许都没有碰到这个问题，也许都己经自己默默的解决了，在此 小记一下，方便后人，也方便自己 查寻。

例子 ： 原字符   "过年"

httpencode('过年') 结果 ：

XE5为  %B9%FD%C4%EA

XE7 调用 相当函数结果 %E8%BF%87%E5%B9%B4

百思不得其解啊，折腾了很长时间，后来终于想到是不是 此函数 官方更新修改了，（没办法，人比较笨）

于是查看源码：

XE5的 web.httpapp 中（分string 和 ansistring， 我用ansistring 版本得到 期望的结果）：

 function HTTPEncode(const AStr: string): string;
 // The NoConversion set contains characters as specificed in RFC 1738 and
 // should not be modified unless the standard changes.
 const
   NoConversion = [Ord('A')..Ord('Z'), Ord('a')..Ord('z'), Ord('*'), Ord('@'),
                   Ord('.'), Ord('_'), Ord('-'), Ord('')..Ord(''), Ord('$'),
                   Ord('!'), Ord(''''), Ord('('), Ord(')')];
 var
   Sp, Rp: PChar;
 begin
   SetLength(Result, Length(AStr) * );
   Sp := PChar(AStr);
   Rp := PChar(Result);
   while Sp^ <> # do
   begin
     if Ord(Sp^) in NoConversion then
       Rp^ := Sp^
     else
       if Sp^ = ' ' then
         Rp^ := '+'
       else
       begin
         FormatBuf(Rp, , string('%%%.2x'), , [Ord(Sp^)]);
         Inc(Rp,);
       end;
     Inc(Rp);
     Inc(Sp);
   end;
   SetLength(Result, Rp - PChar(Result));
 end;

 function HTTPDecode(const AStr: string): string;
 var
   Sp, Rp, Cp: PChar;
   S: string;
 begin
   SetLength(Result, Length(AStr));
   Sp := PChar(AStr);
   Rp := PChar(Result);
   Cp := Sp;
   try
     while Sp^ <> # do
     begin
       case Sp^ of
         '+': Rp^ := ' ';
         '%': begin
                // Look for an escaped % (%%) or %<hex> encoded character
                Inc(Sp);
                if Sp^ = '%' then
                  Rp^ := '%'
                else
                begin
                  Cp := Sp;
                  Inc(Sp);
                  if (Cp^ <> #) and (Sp^ <> #) then
                  begin
                    S := Char('$') + Cp^ + Sp^;
                    Rp^ := Char(StrToInt(string(S)));
                  end
                  else
                    raise EWebBrokerException.CreateFmt(sErrorDecodingURLText, [Cp - PChar(AStr)]);
                end;
              end;
       else
         Rp^ := Sp^;
       end;
       Inc(Rp);
       Inc(Sp);
     end;
   except
     on E:EConvertError do
       raise EConvertError.CreateFmt(sInvalidURLEncodedChar,
         [Char('%') + Cp^ + Sp^, Cp - PChar(AStr)])
   end;
   SetLength(Result, Rp - PChar(Result));
 end;

 function HTTPEncode(const AStr: AnsiString): AnsiString;
 // The NoConversion set contains characters as specificed in RFC 1738 and
 // should not be modified unless the standard changes.
 const
   NoConversion = ['A'..'Z','a'..'z','*','@','.','_','-',
                   ''..'','$','!','''','(',')'];
 var
   Sp, Rp: PAnsiChar;
 begin
   SetLength(Result, Length(AStr) * );
   Sp := PAnsiChar(AStr);
   Rp := PAnsiChar(Result);
   while Sp^ <> # do
   begin
     if Sp^ in NoConversion then
       Rp^ := Sp^
     else
       if Sp^ = ' ' then
         Rp^ := '+'
       else
       begin
         System.AnsiStrings.FormatBuf(Rp^, , AnsiString('%%%.2x'), , [Ord(Sp^)]);
         Inc(Rp,);
       end;
     Inc(Rp);
     Inc(Sp);
   end;
   SetLength(Result, Rp - PAnsiChar(Result));
 end;

在XE7中

web.httpapp:

function HTTPEncode(const AStr: string): string;
begin
  Result := TNetEncoding.URL.Encode(AStr);
end;

查看 system.netencoding

找到

function TNetEncoding.DoEncode(const Input: array of Byte): TBytes;
begin
  Result := TEncoding.UTF8.GetBytes(DoEncode(TEncoding.UTF8.GetString(@Input[])));
end;

查看类定义：  
TURLEncoding = class(TNetEncoding)
  protected
    function DoDecode(const Input: string): string; overload; override;
    function DoEncode(const Input: string): string; overload; override;
  end;

查看函数代码：

function TURLEncoding.DoEncode(const Input: string): string;
// The NoConversion set contains characters as specificed in RFC 1738 and
// should not be modified unless the standard changes.
const
  NoConversion = [Ord('A')..Ord('Z'), Ord('a')..Ord('z'), Ord('*'), Ord('@'),
                  Ord('.'), Ord('_'), Ord('-'), Ord('')..Ord(''), Ord('$'),
                  Ord('!'), Ord(''''), Ord('('), Ord(')')];

  procedure AppendByte(B: Byte; var Buffer: PChar);
  const
    Hex = '0123456789ABCDEF';
  begin
    Buffer[] := '%';
    Buffer[] := Hex[B shr  + Low(string)];
    Buffer[] := Hex[B and $F + Low(string)];
    Inc(Buffer, );
  end;

var
  Sp, Rp: PChar;
  MultibyteChar: TBytes;
  I, ByteCount: Integer;
begin
  // Characters that require more than 1 byte are translated as "percent-encoded byte"
  // which will be encoded with 3 chars per byte -> %XX
  // Example: ?character
  //   Multibyte representation: C391 (2 bytes)
  //   URL encode representation: %C3%91
  //
  // So the worst case is 4 bytes(max) per Char, and 3 characters to represent each byte
  SetLength(Result, Length(Input) *  * );
  Sp := PChar(Input);
  Rp := PChar(Result);
  SetLength(MultibyteChar, );
  while Sp^ <> # do
  begin
    if Ord(Sp^) in NoConversion then
    begin
      Rp^ := Sp^;
      Inc(Rp)
    end
    else if Sp^ = ' ' then
    begin
      Rp^ := '+';
      Inc(Rp)
    end
    else
    begin
      if (Ord(Sp^) < ) then
        // Single byte char
        AppendByte(Ord(Sp^), Rp)
      else
      begin
        // Multi byte char
        ByteCount := TEncoding.UTF8.GetBytes([Sp^], , , MultibyteChar, );
        for I :=  to ByteCount -  do
          AppendByte(MultibyteChar[I], Rp);
      end
    end;
    Inc(Sp);
  end;
  SetLength(Result, Rp - PChar(Result));
end;

似乎有点不同。

目前是我自己建立一个函数 ，复制XE5版本的 代码 放在XE7里面调用，得到希望的结果的。

代码：

function MyHTTPEncode(const AStr: AnsiString): AnsiString;
// The NoConversion set contains characters as specificed in RFC 1738 and
// should not be modified unless the standard changes.
const
  NoConversion = ['A'..'Z','a'..'z','*','@','.','_','-',
                  ''..'','$','!','''','(',')'];
var
  Sp, Rp: PAnsiChar;
begin
  SetLength(Result, Length(AStr) * );
  Sp := PAnsiChar(AStr);
  Rp := PAnsiChar(Result);
  while Sp^ <> # do
  begin
    if Sp^ in NoConversion then
      Rp^ := Sp^
    else
      if Sp^ = ' ' then
        Rp^ := '+'
      else
      begin
        System.AnsiStrings.FormatBuf(Rp^, , AnsiString('%%%.2x'), , [Ord(Sp^)]);
        Inc(Rp,);
      end;
    Inc(Rp);
    Inc(Sp);
  end;
  SetLength(Result, Rp - PAnsiChar(Result));
end;