用HttpWebRequest POST方式向JAVA编写的网页传递数据为什么总是乱码？

myEncoding = Encoding.GetEncoding("utf-8"); 

string param = "";



                                    if (!string.IsNullOrEmpty(cutWaterArea))

                                    {

                                        param += "," + "\"cutWaterArea\":\"" + HttpUtility.UrlEncode(cutWaterArea, myEncoding) + "\"";

                                    }

                                    if (!string.IsNullOrEmpty(temporaryId))

                                    {

                                        param += "," + "\"temporaryId\":\"" + temporaryId + "\"";

                                    }

                                    if (!string.IsNullOrEmpty(cutWaterTime))

                                    {

                                        param += "," + "\"cutWaterTime\":\"" + cutWaterTime + "\"";

                                    }

                                    if (!string.IsNullOrEmpty(cutWaterType))

                                    {

                                        param += "," + "\"cutWaterType\":\"" + HttpUtility.UrlEncode(cutWaterType, myEncoding) + "\"";

                                    }

                                    if (!string.IsNullOrEmpty(topRow))

                                    {

                                        param += "," + "\"topRow\":\"" + HttpUtility.UrlEncode(topRow, myEncoding) + "\"";

                                    }

                                    if (!string.IsNullOrEmpty(recoverTime))

                                    {

                                        param += "," + "\"recoverTime\":\"" + recoverTime + "\"";

                                    }

                                    if (!string.IsNullOrEmpty(detail))

                                    {

                                        param += "," + "\"detail\":\"" + HttpUtility.UrlEncode(detail, myEncoding) + "\"";

                                    }





                                    //myEncoding = Encoding.GetEncoding("ISO-8859-1");



                                    //string param = "";



                                    //if (!string.IsNullOrEmpty(cutWaterArea))

                                    //{

                                    //    param += "," + "\"cutWaterArea\":" + cutWaterArea;

                                    //}

                                    //if (!string.IsNullOrEmpty(temporaryId))

                                    //{

                                    //    param += "," + "\"temporaryId\":" + temporaryId;

                                    //}

                                    //if (!string.IsNullOrEmpty(cutWaterTime))

                                    //{

                                    //    param += "," + "\"cutWaterTime\":" + cutWaterTime;

                                    //}

                                    //if (!string.IsNullOrEmpty(cutWaterType))

                                    //{

                                    //    param += "," + "\"cutWaterType\":" + cutWaterType;

                                    //}

                                    //if (!string.IsNullOrEmpty(topRow))

                                    //{

                                    //    param += "," + "\"topRow\":" + topRow;

                                    //}

                                    //if (!string.IsNullOrEmpty(recoverTime))

                                    //{

                                    //    param += "," + "\"recoverTime\":" + recoverTime;

                                    //}

                                    //if (!string.IsNullOrEmpty(detail))

                                    //{

                                    //    param += "," + "\"detail\":" + detail;

                                    //}





                                    param = "{" + param.TrimStart(',') + "}";





                                    byte[] bs = Encoding.ASCII.GetBytes(param);     //将参数转化为assic码



                                    if (sffs == "0")

                                    {

                                        url = "http://xx/xx/xx.do";

                                    }

                                    else

                                    {

                                        url = "http://xx/xx/xx.do ";

                                    }



                                    HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);



                                    req.Method = "POST";



                                    req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";



                                    req.ContentLength = bs.Length; 





                                    using (Stream reqStream = req.GetRequestStream())

                                    {



                                        reqStream.Write(bs, 0, bs.Length);



                                    }



                                    using (WebResponse wr = req.GetResponse())

                                    {



                                        //在这里对接收到的页面内容进行处理 

                                        Stream responseStream = wr.GetResponseStream();

                                        StreamReader streamReader = new StreamReader(responseStream, Encoding.UTF8);

                                        string html = streamReader.ReadToEnd();



                                        if (PublicMethod.NeedLog)

                                            PublicMethod.WriteStringToFile(System.Threading.Thread.GetDomain().BaseDirectory + "\\WinServer_Yyxt_log.txt", html);



                                    }