Solve Delphi7 built-in UTF-8 encoding conversion Function Bug

Delphi7 and earlier versions of VCL only support ANSI, so... widestring and utf8string (same definition as ansistring) cannot be correctly displayed in VCL

The UTF-8 conversion function provided by Delphi7 returns NULL if it encounters a character string that cannot be identified.

Use the following conversion function to solve this bug:

unit util_utf8; interface uses Windows; type  UTF8String = AnsiString;   function AnsiToWide(const S: AnsiString): WideString;  function WideToUTF8(const WS: WideString): UTF8String;  function AnsiToUTF8(const S: AnsiString): UTF8String;  function UTF8ToWide(const US: UTF8String): WideString;  function WideToAnsi(const WS: WideString): AnsiString;  function UTF8ToAnsi(const S: UTF8String): AnsiString; implementation function AnsiToWide(const S: AnsiString): WideString;var  len: integer;  ws: WideString;begin  Result:=‘‘;  if (Length(S) = 0) then    exit;  len:=MultiByteToWideChar(CP_ACP, 0, PChar(s), -1, nil, 0);  SetLength(ws, len);  MultiByteToWideChar(CP_ACP, 0, PChar(s), -1, PWideChar(ws), len);  Result:=ws;end; function WideToUTF8(const WS: WideString): UTF8String;var  len: integer;  us: UTF8String;begin  Result:=‘‘;  if (Length(WS) = 0) then    exit;  len:=WideCharToMultiByte(CP_UTF8, 0, PWideChar(WS), -1, nil, 0, nil, nil);  SetLength(us, len);  WideCharToMultiByte(CP_UTF8, 0, PWideChar(WS), -1, PChar(us), len, nil, nil);  Result:=us;end; function AnsiToUTF8(const S: AnsiString): UTF8String;begin  Result:=WideToUTF8(AnsiToWide(S));end; function UTF8ToWide(const US: UTF8String): WideString;var  len: integer;  ws: WideString;begin  Result:=‘‘;  if (Length(US) = 0) then    exit;  len:=MultiByteToWideChar(CP_UTF8, 0, PChar(US), -1, nil, 0);  SetLength(ws, len);  MultiByteToWideChar(CP_UTF8, 0, PChar(US), -1, PWideChar(ws), len);  Result:=ws;end; function WideToAnsi(const WS: WideString): AnsiString;var  len: integer;  s: AnsiString;begin  Result:=‘‘;  if (Length(WS) = 0) then    exit;  len:=WideCharToMultiByte(CP_ACP, 0, PWideChar(WS), -1, nil, 0, nil, nil);  SetLength(s, len);  WideCharToMultiByte(CP_ACP, 0, PWideChar(WS), -1, PChar(s), len, nil, nil);  Result:=s;end; function UTF8ToAnsi(const S: UTF8String): AnsiString;begin  Result:=WideToAnsi(UTF8ToWide(S));end; end.

 

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, IdBaseComponent, IdComponent, IdTCPConnection,  IdTCPClient, IdHTTP;type  TForm1 = class(TForm)    Button1: TButton;    Memo1: TMemo;    IdHTTP1: TIdHTTP;    procedure Button1Click(Sender: TObject);  private    { Private declarations }  public    { Public declarations }  end;var  Form1: TForm1;implementationuses  util_utf8;{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);var  strm: TStringStream;begin  strm := TStringStream.Create(‘‘);  try    IdHTTP1.Get(‘http://gz.ganji.com/zpshichangyingxiao/‘, strm);    Memo1.Clear;    Memo1.Lines.Add(UTF8ToAnsi(strm.DataString));  finally    strm.Free;  end;end;end.

Form file

object Form1: TForm1  Left = 206  Top = 211  Width = 783  Height = 540  Caption = ‘Form1‘  Color = clBtnFace  Font.Charset = DEFAULT_CHARSET  Font.Color = clWindowText  Font.Height = -11  Font.Name = ‘MS Sans Serif‘  Font.Style = []  OldCreateOrder = False  PixelsPerInch = 96  TextHeight = 13  object Button1: TButton    Left = 56    Top = 40    Width = 75    Height = 25    Caption = ‘Button1‘    TabOrder = 0    OnClick = Button1Click  end  object Memo1: TMemo    Left = 24    Top = 88    Width = 737    Height = 409    Lines.Strings = (      ‘Memo1‘)    ScrollBars = ssVertical    TabOrder = 1  end  object IdHTTP1: TIdHTTP    MaxLineAction = maException    ReadTimeout = 0    AllowCookies = True    ProxyParams.BasicAuthentication = False    ProxyParams.ProxyPort = 0    Request.ContentLength = -1    Request.ContentRangeEnd = 0    Request.ContentRangeStart = 0    Request.ContentType = ‘text/html‘    Request.Accept = ‘text/html, */*‘    Request.BasicAuthentication = False    Request.UserAgent = ‘Mozilla/3.0 (compatible; Indy Library)‘    HTTPOptions = [hoForceEncodeParams]    Left = 240    Top = 48  endend

　　

　　

Test results: