Delphi讀取和寫入utf-8編碼格式的文件

讀取UTF-8格式的文件內容

function LoadUTF8File(AFileName: string): string;
var  ffileStream:TFileStream; 
         fAnsiBytes: string;
         S: string;
begin
            ffileStream:=TFileStream.Create(AFileName,fmOpenRead);
            SetLength(S,ffileStream.Size); 
            ffileStream.Read(S[1],Length(S));
            fAnsiBytes:= UTF8Decode(Copy(S,4,MaxInt));
           Result:= fAnsiBytes;
end;

寫入UTF-8編碼格式的文件

procedure SaveUTF8File(AContent:string;AFileName: string);
var ffileStream:TFileStream;
        futf8Bytes: string;
       S: string;
begin
       ffileStream:=TFileStream.Create(AFileName,fmCreate); 
       futf8Bytes:= UTF8Encode(AContent); 
       S:=#$EF#$BB#$BF; 
       ffileStream.Write(S[1],Length(S)); 
       ffileStream.Write(futf8Bytes[1],Length(futf8Bytes)); 
       ffileStream.Free;
end;

利用delphi自帶的UTF8Encode函數，將普通字符轉換為utf-8編碼

創建一個流，MemoryStream或FileStream都可

函數看起來如下

引用

procedure SaveUTF8File(AContent:WideString;AFileName: string); 
var 
  ffileStream:TFileStream; 
  futf8Bytes: string; 
  S: string; 
begin 
  ffileStream:=TFileStream.Create(AFileName,fmCreate); 
  futf8Bytes:= UTF8Encode(AContent); 
  ffileStream.Write(futf8Bytes[1],Length(futf8Bytes)); 
  ffileStream.Free; 
end;

 

運行后查看生成的文件，全是亂碼，上網搜索發現

unicode文本文件：頭兩個字符分別是FF   FE（16進制） 
utf-8文本文件：頭兩個字符分別是EF   BB（16進制）

原來是忘了把文件頭加進去了

於是加入代碼后

procedure SaveUTF8File(AContent:WideString;AFileName: string); 
var 
  ffileStream:TFileStream; 
  futf8Bytes: string; 
  S: string; 
begin 
  ffileStream:=TFileStream.Create(AFileName,fmCreate); 
  futf8Bytes:= UTF8Encode(AContent); 
  S:=#$EF#$BB#$BF; 
  ffileStream.Write(S[1],Length(S)); 
  ffileStream.Write(futf8Bytes[1],Length(futf8Bytes)); 
  ffileStream.Free; 
end;

保存文件后查看，還是亂碼。找了半天問題最后終於發現問題出現在聲明的參數WideString上，改成string就沒問題了。

最后生成 的代碼如下

procedure SaveUTF8File(AContent:string;AFileName: string); 
var 
  ffileStream:TFileStream; 
  futf8Bytes: string; 
  S: string; 
begin 
  ffileStream:=TFileStream.Create(AFileName,fmCreate); 
  futf8Bytes:= UTF8Encode(AContent); 
  S:=#$EF#$BB#$BF; 
  ffileStream.Write(S[1],Length(S)); 
  ffileStream.Write(futf8Bytes[1],Length(futf8Bytes)); 
  ffileStream.Free; 
end;

再附上一段讀取utf-8文本的代碼

function  LoadUTF8File(AFileName: string): string; 
var 
  ffileStream:TFileStream; 
  fAnsiBytes: string; 
  S: string; 
begin 
  ffileStream:=TFileStream.Create(AFileName,fmOpenRead); 
  SetLength(S,ffileStream.Size); 
  ffileStream.Read(S[1],Length(S)); 
  fAnsiBytes:= UTF8Decode(Copy(S,4,MaxInt)); 
  Result:= fAnsiBytes; 
end;