使用RSClientPrint直接打印本地RDLC报表

　　最近一个项目使用ReportViewer来呈现本地RDLC模块的报表，需要用户点击至少三次才能直正打印，用户感觉易用性很不好，需要我们修改。

　　经过网上查找相关资料，发现直接使用ACTIVEX控件RSClientPrint直接打印使用SQLSERVER报表服务的资料很多，也说的比较详细，可唯独没打印本地报表的相关内容，看来只能自已摸索了。

　　经过研究有关打印SQLSERVER报表服务的资料，特别是这篇文章：http://www.codeproject.com/KB/reporting-services/RsClientPrint.aspx，决下先写一个简单的HTML文件测试一下：

代码

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
</head>
<BODY onload="Print()">
                <OBJECT ID="RSClientPrint"
classid="CLSID:5554DCB0-700B-498D-9B58-4E40E5814405" CODEBASE="/RSClientPrint-x86.cab" VIEWASTEXT></OBJECT>
                <script type="text/javascript" language="javascript">
                    function Print(oid,name) {
                        if (typeof RSClientPrint.Print == "undefined") {
                            alert("Unable to load client print control.");
                            return;
                        }
                        RSClientPrint.MarginLeft = 0;
                        RSClientPrint.MarginTop = 0;
                        RSClientPrint.MarginRight = 0;
                        RSClientPrint.MarginBottom = 0;
                        RSClientPrint.PageHeight = 296.926;
                        RSClientPrint.PageWidth = 210.058;

                        RSClientPrint.Culture = 2052;
                        RSClientPrint.UICulture = 2052;
                        RSClientPrint.UseSingleRequest = true;
                        RSClientPrint.UseEmfPlus = true;

                        RSClientPrint.Print("http://localhost:2940/JDCJY/ReportHandler.ashx", "oid="+escape(oid)+"&name="+escape(name), "test");
                    }
                </script>



                </BODY>
</html>

　　然后实现ReportHandler.ashx

代码

public class ReportHandler : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {

            Warning[] warningArray;
            HttpResponse response = context.Response;
            response.StatusCode = 200;
            MemoryStream lastMemoryStream = null;
            context.Response.BufferOutput = false;
            context.Response.ContentType = null;
            context.Response.Expires = -1;

            var ds = new DataSet();
            LocalReport localReport = new LocalReport();
            localReport.ReportEmbeddedResource = string.Format("{0}.rdlc", context.Request.QueryString["name"]);
            localReport.DataSources.Add(new Microsoft.Reporting.WebForms.ReportDataSource("ds", ds));
            StringBuilder builder = new StringBuilder("<DeviceInfo>");
            NameValueCollection requestParameters = context.Request.QueryString ;
            for (int i = 0; i < requestParameters.Count; i++)
            {
                if (requestParameters.Keys[i] != null)
                {
                    if (requestParameters.Keys[i].StartsWith("rc:", StringComparison.OrdinalIgnoreCase))
                    {
                        builder.AppendFormat("<{0}>{1}</{0}>", XmlConvert.EncodeName(requestParameters.Keys[i].Substring(3)), HttpUtility.HtmlEncode(requestParameters[i]));
                    }
                }
            }
            builder.Append("</DeviceInfo>");

            localReport.Render("IMAGE", builder.ToString(), delegate(string name, string extension, Encoding encoding, string mimeType, bool willSeek)
            {
                if (!HttpContext.Current.Response.IsClientConnected)
                {
                    throw new HttpException("Client disconnected");
                }
                if (lastMemoryStream != null)
                {
                    this.SendPrintStream(lastMemoryStream, response);
                    lastMemoryStream.Dispose();
                    lastMemoryStream = null;
                }
                lastMemoryStream = new MemoryStream();
                return lastMemoryStream;
            }, out warningArray);
            this.SendPrintStream(lastMemoryStream, response);
            lastMemoryStream.Dispose();
            this.SendPrintStream(null, response);

            if (!response.BufferOutput)
            {
                string a = context.Request.ServerVariables["SERVER_PROTOCOL"];
                if (string.Equals(a, "HTTP/1.0", StringComparison.OrdinalIgnoreCase))
                {
                    context.Response.Close();
                }
            }

        }

        private void SendPrintStream(Stream stream, HttpResponse response)
        {
            int length = 0;
            if (stream != null)
            {
                length = (int)stream.Length;
            }
            foreach (byte num2 in BitConverter.GetBytes(length))
            {
                response.OutputStream.WriteByte(num2);
            }
            if (stream != null)
            {
                stream.Position = 0L;
                StreamToResponse(stream, response);
                response.Flush();
            }
        }

        internal static void StreamToResponse(Stream data, HttpResponse response)
        {
            int count = 0;
            byte[] buffer = new byte[0x14000];
            while ((count = data.Read(buffer, 0, 0x14000)) > 0)
            {
                response.OutputStream.Write(buffer, 0, count);
            }
        }

        public bool IsReusable
        {
            get
            {
                return true;
            }
        }
    }

　　再后经测试，直接加载上面的HTML页面就会提示直接打印。整个过程花了不少时间，有几个地方需要注意：

1.在服务器端生成DEVICEINFO时一定要使用上面所示的方法，我在测试过程中为了图简单，直接使用我原来在WINFORM写的一个代码，固定的DEVICEINFO信息，结果打印出来时始终会重复，不知道是怎么回事，经过使用Reflector反编译Microsoft.ReportViewer.WebForms，仔细这里面实现的报表相关服务，发现这点实现的区别，才最终搞定问题

2.服务器代码生成EMF流如果有问题，客户端会报一个错误代码，这时你很可能会以为是客户端的错误，我开始就是，因为报错误的速度太快了。我上网对对应问题代码的资料也没有明确结果，最后看还是直接跟踪代码试试，发现是服务器端代码有些问题。