ashx正确读取json数据代码

        public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData)
        {
            ......
String content = context.Request.Params["content"];
byte[] byts = new byte[context.Request.InputStream.Length];
        context.Request.InputStream.Read(byts, 0, byts.Length);
        string req = System.Text.Encoding.Default.GetString(byts);
......
        }