摘要
在一些项目中需要在线预览office文档，包括word，excel，ppt等。达到预览文档的目的有很多方法，可以看我之前总结，在线预览的n种方案：
[Asp.net]常见word，excel，ppt，pdf在线预览方案，有图有真相，总有一款适合你！
，由于客户那里有安装web office apps服务，调用该服务就可以实现文档的在线预览，所以在项目中就采用了这种方式，下面列出了实践步骤。
步骤
定义文件信息：
该信息用来调用web office apps服务回调查找文件信息时用到。
public class CheckFileInfo { public CheckFileInfo(); public string BaseFileName { get; set; } public string OwnerId { get; set; } public long Size { get; set; } public string SHA256 { get; set; } public string Version { get; set; } }
获取文件信息的接口
public interface IFileHelper { Task<CheckFileInfo> GetFileInfo(string fileMD5); Task<string> GetSHA256Async(string url); string GetSHA256Async(byte[] buffer); }
接口实现
public class FileHelper : IFileHelper { FileBusiness _FileBusiness; public FileHelper() { _FileBusiness = new FileBusiness(); } /// <summary> /// 获取文件信息 /// </summary> /// <param name="filePath"></param> /// <returns></returns> public async Task<CheckFileInfo> GetFileInfo(string fileMD5) { var fileInfo = _FileBusiness.FindFileByMD5(fileMD5); if (fileInfo != null) { var rv = new CheckFileInfo { Version = DateTime.Now.ToString("s"), Size = Convert.ToInt64(fileInfo.FileSize), OwnerId = fileInfo.Itcode, BaseFileName = fileInfo.FileName, SHA256 = fileInfo.SHA256 }; if (string.IsNullOrEmpty(fileInfo.SHA256)) { rv.SHA256 = await GetSHA256Async(fileInfo.Url); fileInfo.SHA256 = rv.SHA256; await _FileBusiness.UpldateAsyncByUrl(fileInfo); } return rv; } else { return null; } } public async Task<string> GetSHA256Async(string url) { string sha256 = string.Empty; using (var sha = SHA256.Create()) { WebClient webClient = new WebClient(); byte[] buffer = await webClient.DownloadDataTaskAsync(url); byte[] checksum = sha.ComputeHash(buffer); sha256 = Convert.ToBase64String(checksum); } return sha256; } public string GetSHA256Async(byte[] buffer) { string sha256 = string.Empty; using (var sha = SHA256.Create()) { WebClient webClient = new WebClient(); byte[] checksum = sha.ComputeHash(buffer); sha256 = Convert.ToBase64String(checksum); } return sha256; } }
这里用到了文件分布式存储，要预览的放在了另外的文件服务器上面，所以这里使用webclient下载，获取到文件信息，保存在数据库中，如果存在则直接返回。当然，你可以使用FileStream来读取文件的响应信息。
获取文件预览的地址
根据web office apps服务的地址，文件扩展名获取预览的link
using H5.Utility; using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Web; using System.Xml.Serialization; namespace WebSite.OfficeViewerService.Helpers { /// <summary> /// /// </summary> public class WopiAppHelper { public WopiAppHelper() { } /// <summary> /// 获取office在线预览的链接 /// </summary> /// <param name="fileMD5"></param> /// <param name="ext"></param> /// <returns></returns> public string GetDocumentLink(string fileMD5, string ext) { string apiUrl = string.Format(ConfigManager.OWA_MY_VIEW_URL, fileMD5); return string.Format("{0}{1}{2}&access_token={3}", ConfigManager.OWA_URL, FindUrlByExtenstion(ext), apiUrl, fileMD5); } /// <summary> /// 根据文件扩展名获取预览url /// </summary> /// <param name="ext"></param> /// <returns></returns> private string FindUrlByExtenstion(string ext) { if (string.IsNullOrEmpty(ext)) { throw new ArgumentNullException("extension is empty."); } if (ext.IndexOf(".") >= 0) { //如果包含.则进行过滤 ext = ext.TrimStart('.'); } Dictionary<string, string> dic = new Dictionary<string, string>() { {"ods","/x/_layouts/xlviewerinternal.aspx?WOPISrc="}, {"xls", "/x/_layouts/xlviewerinternal.aspx?WOPISrc="}, {"xlsb", "/x/_layouts/xlviewerinternal.aspx?WOPISrc="}, {"xlsm", "/x/_layouts/xlviewerinternal.aspx?WOPISrc="}, {"xlsx", "/x/_layouts/xlviewerinternal.aspx?WOPISrc="}, {"one", "/o/onenoteframe.aspx?WOPISrc="}, {"onetoc2", "/o/onenoteframe.aspx?WOPISrc="}, {"odp", "/p/PowerPointFrame.aspx?WOPISrc="}, {"pot", "/p/PowerPointFrame.aspx?WOPISrc="}, {"potm", "/p/PowerPointFrame.aspx?WOPISrc="}, {"potx", "/p/PowerPointFrame.aspx?WOPISrc="}, {"pps", "/p/PowerPointFrame.aspx?WOPISrc="}, {"ppsm", "/p/PowerPointFrame.aspx?WOPISrc="}, {"ppsx", "/p/PowerPointFrame.aspx?WOPISrc="}, {"ppt", "/p/PowerPointFrame.aspx?WOPISrc="}, {"pptm", "/p/PowerPointFrame.aspx?WOPISrc="}, {"pptx", "/p/PowerPointFrame.aspx?WOPISrc="}, {"doc", "/wv/wordviewerframe.aspx?WOPISrc="}, {"docm", "/wv/wordviewerframe.aspx?WOPISrc="}, {"docx", "/wv/wordviewerframe.aspx?WOPISrc="}, {"dot", "/wv/wordviewerframe.aspx?WOPISrc="}, {"dotm", "/wv/wordviewerframe.aspx?WOPISrc="}, {"dotx", "/wv/wordviewerframe.aspx?WOPISrc="}, {"pdf", "/wv/wordviewerframe.aspx?WOPISrc="} }; return dic[ext]; } } }
web office apps 预览接口回调使用的api时，需要注意尽量传递id之类，如果传递name，文件名涉及到了中文，会有编码的问题，所以我这里传递的是文件的md5值。
using Newtonsoft.Json; using System; using System.IO; using System.Net; using System.Net.Http; using System.Net.Http.Headers; using System.Security.Cryptography; using System.Text; using System.Threading.Tasks; using System.Web; using System.Web.Hosting; using System.Web.Http; using WebSite.OfficeViewerService.Helpers; namespace WebSite.OfficeViewerService.Controllers.Api { /// <summary> /// Primary class for WOPI interface. Supporting the 2 minimal API calls /// requred for base level View /// </summary> public class FilesController : ApiController { IFileHelper _fileHelper; HttpResponseMessage _response; /// <summary> /// Base constructor /// </summary> public FilesController() { _fileHelper = new FileHelper(); _response = new HttpResponseMessage(HttpStatusCode.Accepted); //允许哪些url可以跨域请求到本域 _response.Headers.Add("Access-Control-Allow-Origin", "*"); //允许的请求方法，一般是GET,POST,PUT,DELETE,OPTIONS _response.Headers.Add("Access-Control-Allow-Methods", "POST"); //允许哪些请求头可以跨域 _response.Headers.Add("Access-Control-Allow-Headers", "x-requested-with,content-type"); } /// <summary> /// Required for WOPI interface - on initial view /// </summary> /// <param name="name">file name</param> /// <returns></returns> public async Task<CheckFileInfo> Get(string name) { return await _fileHelper.GetFileInfo(name); } /// <summary> /// Required for WOPI interface - on initial view /// </summary> /// <param name="name">file name</param> /// <param name="access_token">token that WOPI server will know</param> /// <returns></returns> public async Task<CheckFileInfo> Get(string name, string access_token) { return await _fileHelper.GetFileInfo(name); } /// <summary> /// Required for View WOPI interface - returns stream of document. /// </summary> /// <param name="name">file name</param> /// <param name="access_token">token that WOPI server will know</param> /// <returns></returns> public async Task<HttpResponseMessage> GetFile(string name, string access_token) { try { _response.StatusCode = HttpStatusCode.OK; FileBusiness FileBusiness = new FileBusiness(); var file = FileBusiness.FindFileByMD5(name); if (file != null) { WebClient webClient = new WebClient(); byte[] buffer = await webClient.DownloadDataTaskAsync(file.Url); MemoryStream stream = new MemoryStream(buffer); _response.Content = new StreamContent(stream); _response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream"); } return _response; } catch (Exception ex) { _response.StatusCode = HttpStatusCode.InternalServerError; var stream = new MemoryStream(UTF8Encoding.Default.GetBytes(ex.Message ?? "")); _response.Content = new StreamContent(stream); return _response; } } } }
路由配置
using System; using System.Collections.Generic; using System.Linq; using System.Web.Http; namespace WebSite.OfficeViewerService { public static class WebApiConfig { public static void Register(HttpConfiguration config) { // Web API 配置和服务 // Web API 路由 config.Routes.MapHttpRoute( name: "Contents", routeTemplate: "api/wopi/files/{name}/contents", defaults: new { controller = "files", action = "GetFile" } ); config.Routes.MapHttpRoute( name: "FileInfo", routeTemplate: "api/wopi/files/{name}", defaults: new { controller = "Files", action = "Get" } ); config.Routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { controller = "Files", id = RouteParameter.Optional } ); } } }
using System; using System.Collections; using System.Collections.Generic; using System.IO; using System.Linq; using System.Net; using System.Threading.Tasks; using System.Web; using System.Web.Configuration; using System.Web.Hosting; using System.Web.Mvc; using WebSite.OfficeViewerService.Helpers; namespace WebSite.OfficeViewerService.Controllers { public class HomeController : Controller { IFileHelper _fileHelper = new FileHelper(); public ActionResult Index() { return View(); } public async Task<ActionResult> Viewer(string url, string name) { string itcode = string.Empty; try { if (string.IsNullOrEmpty(url)) { throw new ArgumentNullException("Sorry,Url is errr,the file is not found"); }
string fileExt = url.Substring(url.LastIndexOf('.')); WopiAppHelper wopiHelper = new WopiAppHelper(); FileBusiness FileBusiness = new FileBusiness(); var file = FileBusiness.FindFileByUrl(url); string fileMD5 = string.Empty; if (file == null) { WebClient webClient = new WebClient(); byte[] buffer = await webClient.DownloadDataTaskAsync(url); fileMD5 = MD5Helper.GetMD5FromFile(buffer);string sha256 = _fileHelper.GetSHA256Async(buffer); await fastDFSFileBusiness.SaveAsync(new FastDFSFile { Dt = DateTime.Now, FileMd5 = fileMD5, FileName = name, FileSize = buffer.Length, Itcode = itcode, Url = url, SHA256 = sha256 }); } else { fileMD5 = file.FileMd5; } var result = wopiHelper.GetDocumentLink(fileMD5, fileExt); return Redirect(result); } catch (Exception ex) { ViewBag.Message = ex.Message; } return View(); } } }
包装预览接口，其它应用通过传递文件的url和文件名称，然后跳转到实际的预览界面。简单粗暴，不用每个应用都在实现上面的方法。