(401) 从 SharePoint 下载文件时发生未经授权的异常

Question

我已经使用 OAuth 机制为 SharePoint Online 服务器生成了一个访问令牌。我使用此令牌通过 CSOM 创建 ClientContext。虽然我能够无缝访问所有站点、库和文件夹，但我收到错误

The remote server returned an error: (401) Unauthorized.

正在从 SharePoint Online 下载文件。下面是我用于文件下载的代码：

var clientContext = TokenHelper.GetClientContextWithAccessToken("https://adventurer.sharepoint.com/Subsite1", accessToken);
var list = clientContext.Web.Lists.GetByTitle("SubSite 1 Library 1");
string vquery = @"<View Scope='RecursiveAll'><Query><Where><Eq><FieldRef Name='UniqueId' /><Value Type='Lookup'>" + "6718053d-a785-489c-877f-5a4b88dcb2a7" + "</Value></Eq></Where></Query></View>";
CamlQuery query = new CamlQuery();
query.ViewXml = vquery;
var listItems = list.GetItems(query);
clientContext.Load(listItems, items => items.Take(1).Include(item => item.File));
clientContext.ExecuteQuery();

var fileRef = listItems[0].File.ServerRelativeUrl;
var fileInfo = Microsoft.SharePoint.Client.File.OpenBinaryDirect(clientContext, fileRef);

我不明白此错误的根本原因，因为我正在传递具有正确访问令牌的客户端上下文。我想知道 OpenBinaryDirect 是否有使用访问令牌的限制？如果不是，上面的代码有什么问题？是否有任何其他替代方法可用于使用访问令牌下载？

Answer 1

我正在使用 C#，这是我目前从 SharePoint Online 检索文档的方式。我在 gridview 中向用户展示了他们的文档列表，因此我用这些文档填充了一个 DataTable。我不确定使用访问令牌的方法，但如果您能够像我一样使用服务帐户，那么希望这对您有所帮助。

命名空间

using Microsoft.SharePoint.Client;
using SP = Microsoft.SharePoint.Client;

对象属性

SecureString securePassword = new SecureString();
private string username = "";    
ClientContext context = new SP.ClientContext("https://<root>.sharepoint.com/<site collection (unless root)>/<site>");

构造函数（我就是这样验证的）

public SharePoint()
{
    securePassword = convertToSecureString(System.Web.Configuration.WebConfigurationManager.AppSettings["O365PW"]);
    username = System.Web.Configuration.WebConfigurationManager.AppSettings["O365UN"];
    context.Credentials = new SharePointOnlineCredentials(username, securePassword);
}

获取文档的方法

public DataTable GetDocuments(int changeID)
{
    DataTable dt = new DataTable("ChangeDocuments");
    DataRow dr = dt.NewRow();
    dt.Columns.Add("Title");
    dt.Columns.Add("URL");
    dt.Columns.Add("ChangeID");
    dt.Columns.Add("Modified");
    dt.Columns.Add("ID");


    // The SharePoint web at the URL.
    Web web = context.Web;

    // We want to retrieve the web's properties.
    context.Load(web);

    // We must call ExecuteQuery before enumerate list.Fields. 
    context.ExecuteQuery();

   // Assume the web has a list named "Announcements". 
   SP.List oList = context.Web.Lists.GetByTitle("Name of your document library");

   // This creates a CamlQuery that has a RowLimit of 100, and also specifies Scope="RecursiveAll" 
   // so that it grabs all list items, regardless of the folder they are in. 
   CamlQuery query = CamlQuery.CreateAllItemsQuery(100);
query.ViewXml = "<View><Query><Where><Eq><FieldRef Name='ChangeID'/>" +
    "<Value Type='Number'>" + changeID + "</Value></Eq></Where></Query><RowLimit>100</RowLimit></View>";
   SP.ListItemCollection items = oList.GetItems(query);

   // Retrieve all items in the ListItemCollection from List.GetItems(Query). 
   context.Load(items);
   context.ExecuteQuery();

foreach (Microsoft.SharePoint.Client.ListItem listItem in items)
{
    // We have all the list item data. For example, Title. 

    dr = dt.NewRow();

    dr["Title"] = listItem["FileLeafRef"];

    if (String.IsNullOrEmpty(listItem["ServerRedirectedEmbedUrl"].ToString()))
    {
        dr["URL"] = "<root>/<site>/<document library>" + listItem["FileLeafRef"].ToString();
    }
    else
    {
        dr["URL"] = listItem["ServerRedirectedEmbedUrl"];
    }

    dr["ChangeID"] = listItem["ChangeID"];
    dr["Modified"] = Convert.ToDateTime(listItem["Modified"]).ToString("MMM.dd,yyyy h:mm tt");
    dr["ID"] = listItem["ID"];
    dt.Rows.Add(dr);
 }

return dt;
}

将密码转换为安全字符串的方法

private SecureString convertToSecureString(string strPassword)
{
        var secureStr = new SecureString();
        if (strPassword.Length > 0)
        {
            foreach (var c in strPassword.ToCharArray()) secureStr.AppendChar(c);
        }
        return secureStr;
}

Answer 2

在尝试了很多替代方案之后，我得出结论，OpenBinaryDirect() 不能与 OAuth 令牌一起使用。我能够使用其他两种方法从 SharePoint Online 下载文件。我在这里发布答案，以便它可以帮助某人：

方法 1 (OpenBinaryStream):

var file = clientContext.Web.GetFileByServerRelativeUrl(fileRef);
clientContext.Load(file);
clientContext.ExecuteQuery();                    
ClientResult<Stream> streamResult = file.OpenBinaryStream();
clientContext.ExecuteQuery();

虽然此方法非常有效，但 OpenBinaryStream 在 Microsoft.SharePoint.Client.dll <= v 14.0.0.0 中不可用。

方法 2（WebClient 或其他 Http 请求）：

string downloadUrl = HostURL + "/_api/web/getfilebyserverrelativeurl('" + fileRef + "')/$value";
WebClient client = new WebClient(); 
client.Headers.Add("Authorization", "Bearer " + accessToken);
client.DownloadFile(downloadUrl, filePath);

请注意我用于 WebClient 的下载 URL。普通文件 URL 无法从 SharePoint Online 下载文件。

(401) 从 SharePoint 下载文件时发生未经授权的异常

(401) Unauthorized exception while downloading file from SharePoint

sharepoint

sharepoint-2013

csom

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