Dynamic Web TWAIN
存储和检索数字化文档是任何文档管理工作流过程的一个重要特征。本文我们将介绍如何使用ASP.NET Web程序中的文档扫描功能将扫描文件保存为PDF文档，并保存至SQL Server数据库中。在本文中我们将使用Dynamic Web TWAIN来加快文档扫描，上传和显示功能的开发进程。
Dynamic Web TWAIN主要功能：1、Windows或Mac上兼容Firefox，Chrome，Opera和Safari等主流浏览器2、支持从扫描仪或者其他TWAIN兼容设备中扫描图像3、BMP，JPEG，PNG，单/多页 PDF和单/多页TIFF4、支持HTTPS上传5、支持cookie和会话的集成
文件扫描由于Dynamic Web TWAIN是一个客户端SDK，我们将使用JavaScript来调用它的方法/属性。有了扫描识别工具Dynamic Web TWAIN，你可以自定义扫描设置，如分辨率，像素类型，亮度，对比度，页面大小等。本文，我们将重点介绍如何从SQL Server中储存和检索图像。为此，我们将只包括一个简单的扫描过程。function acquireImage() {if (_divDWTSourceContainerID == '')DWObject.SelectSource();elseDWObject.SelectSourceByIndex(document.getElementById(_divDWTSourceContainerID).selectedIndex); //select a TWAIN scannerDWObject.CloseSource(); //make sure the source is closed before using itDWObject.OpenSource();DWObject.IfShowUI = document.getElementById('ShowUI').checked; //show or hide the user interface of the TWAIN scanner var i;for (i = 0; i < 3; i++) {if (document.getElementsByName('PixelType').item(i).checked == true)DWObject.PixelType = i;} // set the pixel type of the acquired images, B/W, gray or colorDWObject.Resolution = document.getElementById('Resolution').value; //set the resolutionDWObject.IfFeederEnabled = document.getElementById('ADF').checked; //scan images from auto feederDWObject.IfDuplexEnabled = document.getElementById('Duplex').checked; //enable duplex scanningappendMessage('Pixel Type: ' + DWObject.PixelType + '
Resolution: ' + DWObject.Resolution + '
'); DWObject.IfDisableSourceAfterAcquire = true;DWObject.AcquireImage(); //start document scanning}
将扫描图像作为个多页PDF保存至SQL Server扫描完成后，你可以将图像保存为多种格式：BMP、PNG、JPG、TIF、PDF、多页PDF或多页TIF。在这个例子中，我们将扫描图像保存为一个多页PDF文件。代码如下所示：function btnUpload_onclick() {if (!checkIfImagesInBuffer()) {return;}var i, strHTTPServer, strActionPage, strImageType;_txtFileName.className = '';if (!strre.test(_txtFileName.value)) {_txtFileName.className += ' invalid';_txtFileName.focus();appendMessage('Please input file name.
Currently only English names are allowed.
');return;}//DWObject.MaxInternetTransferThreads = 5;strHTTPServer = _strServerName;DWObject.HTTPPort = _strPort;var CurrentPathName = unescape(location.pathname); // get current PathName in plain ASCIIvar CurrentPath = CurrentPathName.substring(0, CurrentPathName.lastIndexOf('/') + 1);strActionPage = CurrentPath + _strActionPage; // the aspx page for receiving image data on the server sidevar redirectURLifOK = CurrentPath + 'online_demo_list.aspx';var uploadfilename = _txtFileName.value + '.' + document.getElementsByName('ImageType').item(i).value; DWObject.HTTPUploadAllThroughPostAsPDF(strHTTPServer,strActionPage,uploadfilename); //upload images as multi-page PDF file _strTempStr = _strTempStr + 'Upload: ';if (checkErrorString()) {if (strActionPage.indexOf('SaveToFile') != -1)alert(DWObject.ErrorString)//if save to file.elsewindow.location = redirectURLifOK;}}
Action Page- SaveToDB.aspx动作页面用于接收来自扫描图像的图像数据。<%@ Page Language='C#'%><%try{String strImageName;int iFileLength;HttpFileCollection files = HttpContext.Current.Request.Files;HttpPostedFile uploadfile = files['RemoteFile'];strImageName = uploadfile.FileName;iFileLength = uploadfile.ContentLength; Byte[] inputBuffer = new Byte[iFileLength];System.IO.Stream inputStream; inputStream = uploadfile.InputStream;inputStream.Read(inputBuffer, 0, iFileLength); String strConnString; strConnString = Common.DW_ConnString; System.Data.SqlClient.SqlConnection sqlConnection = new System.Data.SqlClient.SqlConnection(strConnString); String SqlCmdText = 'INSERT INTO ' + Common.DW_SaveTable + ' (strImageName,imgImageData) VALUES (@ImageName,@Image)';System.Data.SqlClient.SqlCommand sqlCmdObj = new System.Data.SqlClient.SqlCommand(SqlCmdText, sqlConnection); sqlCmdObj.Parameters.Add('@Image', System.Data.SqlDbType.Binary, iFileLength).Value = inputBuffer;sqlCmdObj.Parameters.Add('@ImageName', System.Data.SqlDbType.VarChar, 255).Value = strImageName; sqlConnection.Open();sqlCmdObj.ExecuteNonQuery();sqlConnection.Close();}catch{}%>
从Web页面上显示数据库中检索PDF文件Online_demo_view.aspx用于显示PDF文档setTimeout(function () {var CurrentPathName = unescape(location.pathname); // get current PathName in plain ASCIIvar CurrentPath = CurrentPathName.substring(0, CurrentPathName.lastIndexOf('/') + 1);var strActionPage = CurrentPath + 'online_demo_download.aspx'; //the ActionPage's file path strHTTPServer = location.hostname;DWObject.HTTPPort = location.port==''?80:location.port;var downloadsource = strActionPage +'?iImageIndex=<%=strImageID%>&ImageName=<%=strImageName%>&ImageExtName=<%=strImageExtName%>';DWObject.HTTPDownloadEx(strHTTPServer, downloadsource,<%=strImageFileType %>);}, 500);
online_demo_download.aspx用于检索数据库中的图像<%@ Page Language='C#'%> <%String strExc = '';try{//Get the image data from the databaseHttpRequest request = HttpContext.Current.Request; String strImageName;String strImageExtName;String strImageID; strImageName = request['ImageName'];strImageExtName = request['ImageExtName'];strImageID = request['iImageIndex']; String strConnString; strConnString = Common.DW_ConnString; System.Data.SqlClient.SqlConnection sqlConnection = new System.Data.SqlClient.SqlConnection(strConnString);System.Data.SqlClient.SqlCommand sqlCmdObj = new System.Data.SqlClient.SqlCommand('SELECT imgImageData FROM ' +Common.DW_SaveTable + ' WHERE iImageID= ' + strImageID, sqlConnection); sqlConnection.Open(); System.Data.SqlClient.SqlDataReader sdrRecordset = sqlCmdObj.ExecuteReader(); sdrRecordset.Read(); long iByteLength;iByteLength = sdrRecordset.GetBytes(0, 0, null, 0, int.MaxValue); byte[] byFileData = new byte[iByteLength]; sdrRecordset.GetBytes(0, 0, byFileData, 0, Convert.ToInt32(iByteLength)); sdrRecordset.Close();sqlConnection.Close(); sdrRecordset = null;sqlConnection = null; Response.Clear();Response.Buffer = true; if (strImageExtName == 'bmp'){Response.ContentType = 'image/bmp';}else if (strImageExtName == 'jpg'){Response.ContentType = 'image/jpg';}else if (strImageExtName == 'tif'){Response.ContentType = 'image/tiff';}else if (strImageExtName == 'png'){Response.ContentType = 'image/png';}else if (strImageExtName == 'pdf'){Response.ContentType = 'application/pdf';} try{String fileNameEncode;fileNameEncode = HttpUtility.UrlEncode(strImageName, System.Text.Encoding.UTF8);fileNameEncode = fileNameEncode.Replace('+', '%20');String appendedheader = 'attachment;filename=' + fileNameEncode;Response.AppendHeader('Content-Disposition', appendedheader); Response.OutputStream.Write(byFileData, 0, byFileData.Length);}catch (Exception exc){strExc = exc.ToString();DateTime d1 = DateTime.Now;string logfilename = d1.Year.ToString() + d1.Month.ToString() + d1.Day.ToString() +d1.Hour.ToString() + d1.Minute.ToString() + d1.Second.ToString() + 'log.txt';String strField1Path = HttpContext.Current.Request.MapPath('.') + '/' + logfilename;if (strField1Path != null){System.IO.StreamWriter sw1 = System.IO.File.CreateText(strField1Path);sw1.Write(strExc);sw1.Close();}Response.Flush();Response.Close();}}catch (Exception ex){strExc = ex.ToString();DateTime d1 = DateTime.Now;string logfilename = d1.Year.ToString() + d1.Month.ToString() + d1.Day.ToString() +d1.Hour.ToString() + d1.Minute.ToString() + d1.Second.ToString() + 'log.txt';String strField1Path = HttpContext.Current.Request.MapPath('.') + '/' + logfilename;if (strField1Path != null){System.IO.StreamWriter sw1 = System.IO.File.CreateText(strField1Path);sw1.Write(strExc);sw1.Close();}Response.Write(strExc);}%>