请教关于http 的post请求，body为空的问题

[LintyW]

发送的http请求，用抓包软件抓取后发现body没有字节，是空的。请教如何往http post请求的body里添加内容。
我写的代码如下：
idhtp1:=Tidhttp.create(nil);
idslhndlrscktpnsl1 := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
idslhndlrscktpnsl1.SSLOptions.Method:=sslvTLSv1;
idslhndlrscktpnsl1.SSLOptions.Mode:=sslmClient;
idhtp1.IOHandler := idslhndlrscktpnsl1;
idhtp1.Request.AcceptCharSet:='Accept-Charset=utf-8;';
idhtp1.Request.ContentType:='application/x-www-form-urlencoded; charset=UTF-8';
jsonPost:=SO();
ResponseStream1 := TStringStream.Create('');
RequestStream1 := TStringStream.Create('');
jsonPost.s['coupon']:=trim(edtYHQCode.Text);
jsonPost.s['sign']:=tmpStr;
tmpJsonStr:=jsonPost.AsString;
RequestStream1.WriteString(tmpJsonStr);
idhtp1.Post(httpUrl,RequestStream1,ResponseStream1);
json1 := SO(UTF8Decode(ResponseStream1.DataString));

[LintyW]

这么长时间了，结贴