一个项目需要使用TNetHTTPClient带头，提交Json数据。摸索一天之后调试成功，记录一下，以便今后查阅。如果朋友有更好的方法请不吝赐教。具体代码如下：

uses System.Net.URLClient,System.Net.HttpClient;

function HttpPost(Url: String;token,JsonStr:string): String;

var

NetHttp: TNetHTTPClient;

ParmList,TmpSS: TStringStream;

begin

Result := '';

NetHttp := TNetHTTPClient.Create(nil);

ParmList := TStringStream.Create(JsonStr, TEncoding.UTF8);

ParmList.Position :=0;

TmpSS := TStringStream.Create('', TEncoding.UTF8);

TmpSS.Position :=0;

try

NetHttp.ConnectionTimeout := 10000;

NetHttp.ResponseTimeout := 20000;

NetHttp.CustomHeaders['token'] := token;

NetHttp.UserAgent := 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36';

NetHttp.ContentType := 'application/json; charset=utf-8;';

NetHttp.Post(Url, ParmList, TmpSS);

Result := Trim(TmpSS.DataString);

finally

FreeAndNil(NetHttp);

FreeAndNil(ParmList);

FreeAndNil(TmpSS);

end;

end;