INDY10的IDHttpServer应答客户端

首先贴源码：

procedure TIdHTTPResponseInfo.WriteContent;begin  if not HeaderHasBeenWritten then begin    WriteHeader;  end;  // RLebeau 11/23/2014: Per RFC 2616 Section 4.3:  //  // For response messages, whether or not a message-body is included with  // a message is dependent on both the request method and the response  // status code (section 6.1.1). All responses to the HEAD request method  // MUST NOT include a message-body, even though the presence of entity-  // header fields might lead one to believe they do. All 1xx  // (informational), 204 (no content), and 304 (not modified) responses  // MUST NOT include a message-body. All other responses do include a  // message-body, although it MAY be of zero length.  if not (    (FRequestInfo.CommandType = hcHEAD) or    ((ResponseNo div 100) = 1) or    (ResponseNo = 204) or    (ResponseNo = 304)    ) then  begin    // Always check ContentText first    if ContentText <> '' then begin      FConnection.IOHandler.Write(ContentText, CharsetToEncoding(CharSet));    end    else if Assigned(ContentStream) then begin      ContentStream.Position := 0;      FConnection.IOHandler.Write(ContentStream);    end    else begin      FConnection.IOHandler.WriteLn('' + IntToStr(ResponseNo) + ' ' + ResponseText    {Do not Localize}       + '', CharsetToEncoding(CharSet));    {Do not Localize}    end;  end;  // Clear All - This signifies that WriteConent has been called.  ContentText := '';    {Do not Localize}  ReleaseContentStream;end;　

一共可以应答客户端3种内容：

1）ContentText不为空字串，则发送字符串

2）ContentStream对象存在，则发送流

3）不是上面2种情况，则发送的是HTML。

最后会自动清空应答的字串或释放流，这也是为什么我们手动释放流反而会报“非法访问”错误：

ContentText := ''; 

ReleaseContentStream;