在ASP.NET MVC 无需Web Form和Report Viewer 预览SSRS报表解决方案
2013-06-07 20:46 灵感之源 阅读(9900) 评论(12) 编辑 收藏 举报环境
ASP.NET MVC 4.0 + SQL Server Reporting Services
需求
在保存报表为文件（如PDF）之前，可以预览报表（支持图片）。
分析
网络上的解决方案，都是告诉你用最原始的办法：结合ASP.NET Web Form+Report Viewer控件。因为SQL Server Reporting Services (SSRS) 只有Web Form的Report Viewer控件，没对ASP.NET MVC进行特别支持。
我们不能直接在ASP.NET MVC用Report Viewer是因为Report Viewer依赖View State，而View State正是MVC要解决的问题。。。
因为不满意这种整合Web Form的解决方案，今晚思考了一下，既然SSRS支持渲染结果为MHTML（MIME HTML），那么，如果我们解决浏览器不显示MHTML内容（需要另存再本地打开），就可以实现预览的办法：先渲染成MHTML，再解释MIME，再把图片附件转成data嵌入。
步骤
1. 设计页面
因为预览结果是完整的HTML，我在报表页面嵌入了一个iframe。。。。。。src指向一个Web API，该Web API会返回渲染后的html内容（包括图片）。
2. 下载文件
添加一个Web API 函数，用以渲染MHTML并返回text/html结果。为了简化操作，我把报表参数拼接起来，键值用“|”分隔，参数用“`”分隔。实际使用请根据自己的情况修改。。。
public HttpResponseMessage DownloadReportContent(string ReportFileName, string Parameters)
{
var parameters = new Dictionary<string, string>();
Parameters.Split('`').ForEach(p =>
{
var parts = p.Split('|');
parameters.Add(parts[0], parts[1]);
});
byte[] reportContent;
string fileExtension, mimeType;
ReportGenerator.GenerateReport("ReportServer", "ReportServerExecutionURL", "ReportServerUserName", "ReportServerPassword", "ReportServerDomain", ReportFileName, ExportFormat.MHTML, parameters, string.Empty, out reportContent, out fileExtension, out mimeType);
reportContent = ReportConvertor.Convert(reportContent);
var resultStream = new System.IO.MemoryStream(reportContent);
resultStream.Position = 0;
var response = new HttpResponseMessage();
response.StatusCode = HttpStatusCode.OK;
response.Content = new StreamContent(resultStream);
return response;
}
3. 渲染报表为MHTML
下面的方法可以用作渲染其它格式，如最常见的PDF
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Principal;
//using YOUR_IMPORTED_WEB_REFERENCE_FOR_SSRS_EXECUTION_SERVICE_HERE
namespace Org.SSRSPreview
{
/// <summary>
/// Export Formats
/// </summary>
public enum ExportFormat
{
/// <summary>XML</summary>
XML,
/// <summary>Comma Delimitted File
CSV,
/// <summary>TIFF image</summary>
Image,
/// <summary>PDF</summary>
PDF,
/// <summary>HTML (Web Archive)</summary>
MHTML,
/// <summary>HTML 4.0</summary>
HTML4,
/// <summary>HTML 3.2</summary>
HTML32,
/// <summary>Excel</summary>
Excel,
/// <summary>Word</summary>
Word
}
public class ReportGenerator
{
/// <summary>
/// Gets the string export format of the specified enum.
/// </summary>
/// <param name="Format">export format enum</param>
/// <returns>enum equivalent string export format</returns>
private string GetExportFormatString(ExportFormat Format)
{
switch (Format)
{
case ExportFormat.XML: return "XML";
case ExportFormat.CSV: return "CSV";
case ExportFormat.Image: return "IMAGE";
case ExportFormat.PDF: return "PDF";
case ExportFormat.MHTML: return "MHTML";
case ExportFormat.HTML4: return "HTML4.0";
case ExportFormat.HTML32: return "HTML3.2";
case ExportFormat.Excel: return "EXCEL";
case ExportFormat.Word: return "WORD";
default:
return "PDF";
}
}
/// <summary>
/// generate a report
/// </summary>
/// <param name="ReportServer">report server</param>
/// <param name="ReportServerExecutionURL">rendering execution url of report server</param>
/// <param name="ReportServerUserName">user name to access report server</param>
/// <param name="ReportServerPassword">password of the user name</param>
/// <param name="ReportServerDomain">domain of the report server (for active directory)</param>
/// <param name="ReportServerSubDir">folder of the report in the report server</param>
/// <param name="FileFormat">output of the report</param>
/// <param name="Parameters">parameters for the report</param>
/// <param name="ReportContent">rendered report content</param>
/// <param name="FileExtension">file extension of the report</param>
/// <param name="MimeType">mime type of the generated file</param>
public void GenerateReport(string ReportServer,
string ReportServerExecutionURL,
string ReportServerUserName,
string ReportServerPassword,
string ReportServerDomain,
string ReportServerSubDir,
string ReportFileName,
ExportFormat FileFormat,
Dictionary<string, string> Parameters,
string DeviceInfo,
out byte[] ReportContent,
out string FileExtension,
out string MimeType)
{
using (var reportExecutionService = new ReportExecutionService.ReportExecutionServiceSoapClient("ReportExecutionServiceSoap", ReportServerExecutionURL))
{
reportExecutionService.ClientCredentials.Windows.AllowedImpersonationLevel = TokenImpersonationLevel.Impersonation;
reportExecutionService.ClientCredentials.UserName.UserName = ReportServerUserName;
reportExecutionService.ClientCredentials.UserName.Password = ReportServerPassword;
reportExecutionService.ClientCredentials.Windows.ClientCredential = new System.Net.NetworkCredential(ReportServerUserName, ReportServerPassword, ReportServerDomain);
var parameters = Parameters.Select(p => new ParameterValue { Name = p.Key, Value = p.Value }).ToList();
// Init Report to execute
ServerInfoHeader serverInfoHeader;
ExecutionInfo executionInfo;
ExecutionHeader executionHeader = reportExecutionService.LoadReport(null, ReportFileName, null, out serverInfoHeader, out executionInfo);
// Attach Report Parameters
reportExecutionService.SetExecutionParameters(executionHeader, null, parameters.ToArray(), null, out executionInfo);
// Render
string encoding;
Warning[] warnings;
string[] streamIds;
reportExecutionService.Render(executionHeader, null, GetExportFormatString(FileFormat), DeviceInfo, out ReportContent, out FileExtension, out MimeType, out encoding, out warnings, out streamIds);
}
}
}
}
4. 解释MIME，转换图片附件为data嵌入式
这是整个解决方案的核心思想。SSRS会把修改图片的标识，譬如<img src="cid:SOME_ID_HERE">，我们要做的就是取得图片附件的原始base64内容，构造成如下的格式：
data:image/png;base64,[ENCODED_DATA_HERE]
MIME解释用到了OpenPop.NET （通过Pop3协议收取邮件），这是我10年前参与开发的第一个开源项目，不过几年前把项目移交给别的开发人员，我当年写的代码部分都荡然无存了。。。在这里吐槽一下接手的开发人员，你太不给偶面子了。。。 :-)
为了优化性能，我改动了一下MessagePart.cs文件。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using OpenPop.Mime;
namespace Org.SSRSPreview
{
public class ReportConvertor
{
public static byte[] Convert(byte[] Content)
{
var message = new Message(Content);
var body = message.FindFirstHtmlVersion();
var bodyText = body.BodyEncoding.GetString(body.Body, 0, body.Body.Length);
message.FindAllAttachments().ForEach(a =>
{
if (!a.IsText)
{
var key = "Content-Location";
var url = a.Headers.UnknownHeaders[key];
if (string.IsNullOrEmpty(url) && a.ContentDisposition != null)
url = a.ContentDisposition.Inline ? "cid:" + a.FileName : a.FileName;
var attachment = a.Body;
var embedImage = new StringBuilder("data:");
embedImage.Append(a.ContentType.MediaType + ";");
embedImage.Append(a.ContentTransferEncoding.ToString().ToLowerInvariant() + ",");
embedImage.Append(a.BodyEncoding.GetString(a.RawBody));
bodyText = bodyText.Replace(url, embedImage.ToString());
}
});
return body.BodyEncoding.GetBytes(bodyText);
}
}
}
限制
没有Report Viewer那些控制，譬如缩放，分页等。。。。我不需要啊。。。
代码
点击这里下载。代码不是完整的解决方案，只包括关键的代码，如果你打开运行，只会解释一个例子MHTML，因为相关的函数和类都在这里贴了。
总结
至此，大功告成。SQL Server团队对ASP.NET MVC不重视啊，这么多年还不考虑一下支持ASP.NET MVC。
