delphi html decode

问题:

I'm using Delphi 2009 and want to decode an HTML encoded string, for example:

' -> '

But cannot find any built in function for doing this.

Thanks in advance

回答1:

Look at the HTTPApp unit. HTTPDecode and HTMLDecode (as well as the Encode functions). You should find this in your Source/Win32/Internet folder.

回答2:

Here's my HTMLDecode procedure (slightly modified from CGs HTTPApp unit):

function HTMLDecode(const AStr: String): String;
var
  Sp, Rp, Cp, Tp: PChar;
  S: String;
  I, Code: Integer;
begin
  SetLength(Result, Length(AStr));
  Sp := PChar(AStr);
  Rp := PChar(Result);
  Cp := Sp;
  try
    while Sp^ <> #0 do
    begin
      case Sp^ of
        '&': begin
               Cp := Sp;
               Inc(Sp);
               case Sp^ of
                 'a': if AnsiStrPos(Sp, 'amp;') = Sp then  { do not localize }
                      begin
                        Inc(Sp, 3);
                        Rp^ := '&';
                      end;
                 'l',
                 'g': if (AnsiStrPos(Sp, 'lt;') = Sp) or (AnsiStrPos(Sp, 'gt;') = Sp) then { do not localize }
                      begin
                        Cp := Sp;
                        Inc(Sp, 2);
                        while (Sp^ <> ';') and (Sp^ <> #0) do
                          Inc(Sp);
                        if Cp^ = 'l' then
                          Rp^ := '<'
                        else
                          Rp^ := '>';
                      end;
                 'n': if AnsiStrPos(Sp, 'nbsp;') = Sp then  { do not localize }
                      begin
                        Inc(Sp, 4);
                        Rp^ := ' ';
                      end;
                 'q': if AnsiStrPos(Sp, 'quot;') = Sp then  { do not localize }
                      begin
                        Inc(Sp,4);
                        Rp^ := '"';
                      end;
                 '#': begin
                        Tp := Sp;
                        Inc(Tp);
                        while (Sp^ <> ';') and (Sp^ <> #0) do
                          Inc(Sp);
                        SetString(S, Tp, Sp - Tp);
                        Val(S, I, Code);
                        Rp^ := Chr((I));
                      end;
                 else
                   Exit;
               end;
           end
      else
        Rp^ := Sp^;
      end;
      Inc(Rp);
      Inc(Sp);
    end;
  except
  end;
  SetLength(Result, Rp - PChar(Result));
end;

回答3:

The HttpApp.HttpDecode function doesn't decode http entities (https://www.w3.org/TR/html4/sgml/entities.html#sym)

For example: ∴ → ∴

function HtmlDecode(s: UnicodeString): UnicodeString;
{ 
   Public domain: No attribution required
   Known issue, it doesn't handle entities with characters code points above $FFFF (65536)
   e.g.: &