UTF-8 delphi 函数

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;
 
interface
 
uses
  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;
 
implementation
uses
  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.