提取并保存附件

获取所有附件

使用 Aspose.PDF，可以从 PDF 文档中获取所有附件。这在您想要将文档单独保存到 PDF 中，或者需要从 PDF 中删除附件时非常有用。

要从 PDF 文件中获取所有附件：

1. 遍历 Document 对象的 EmbeddedFiles 集合。 EmbeddedFiles 集合包含所有附件。此集合的每个元素代表一个 FileSpecification 对象。通过 EmbeddedFiles 集合的 foreach 循环的每次迭代返回一个 FileSpecification 对象。
2. 一旦对象可用，检索附加文件的所有属性或文件本身。

以下代码片段展示了如何从 PDF 文档中获取所有附件。

以下代码片段也适用于 Aspose.PDF.Drawing 库。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetAllAttachments()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Attachments();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "GetAlltheAttachments.pdf"))
    {
        // Get embedded files collection
        Aspose.Pdf.EmbeddedFileCollection embeddedFiles = document.EmbeddedFiles;

        // Get count of the embedded files
        Console.WriteLine("Total files : {0}", embeddedFiles.Count);

        int count = 1;

        // Loop through the collection to get all the attachments
        foreach (Aspose.Pdf.FileSpecification fileSpecification in embeddedFiles)
        {
            Console.WriteLine("Name: {0}", fileSpecification.Name);
            Console.WriteLine("Description: {0}",
            fileSpecification.Description);
            Console.WriteLine("Mime Type: {0}", fileSpecification.MIMEType);

            // Check if parameter object contains the parameters
            if (fileSpecification.Params != null)
            {
                Console.WriteLine("CheckSum: {0}",
                fileSpecification.Params.CheckSum);
                Console.WriteLine("Creation Date: {0}",
                fileSpecification.Params.CreationDate);
                Console.WriteLine("Modification Date: {0}",
                fileSpecification.Params.ModDate);
                Console.WriteLine("Size: {0}", fileSpecification.Params.Size);
            }

            // Get the attachment and write to file or stream
            var fileContent = new byte[fileSpecification.Contents.Length];
            fileSpecification.Contents.Read(fileContent, 0, fileContent.Length);
            using (var fileStream = new FileStream(dataDir + count + "_out" + ".txt", FileMode.Create))
            {
                fileStream.Write(fileContent, 0, fileContent.Length);
            }
            count += 1;
        }
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetAllAttachments()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Attachments();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "GetAlltheAttachments.pdf");

    // Get embedded files collection
    Aspose.Pdf.EmbeddedFileCollection embeddedFiles = document.EmbeddedFiles;

    // Get count of the embedded files
    Console.WriteLine("Total files : {0}", embeddedFiles.Count);

    int count = 1;

    // Loop through the collection to get all the attachments
    foreach (Aspose.Pdf.FileSpecification fileSpecification in embeddedFiles)
    {
        Console.WriteLine("Name: {0}", fileSpecification.Name);
        Console.WriteLine("Description: {0}",
        fileSpecification.Description);
        Console.WriteLine("Mime Type: {0}", fileSpecification.MIMEType);

        // Check if parameter object contains the parameters
        if (fileSpecification.Params != null)
        {
            Console.WriteLine("CheckSum: {0}",
            fileSpecification.Params.CheckSum);
            Console.WriteLine("Creation Date: {0}",
            fileSpecification.Params.CreationDate);
            Console.WriteLine("Modification Date: {0}",
            fileSpecification.Params.ModDate);
            Console.WriteLine("Size: {0}", fileSpecification.Params.Size);
        }

        // Get the attachment and write to file or stream
        var fileContent = new byte[fileSpecification.Contents.Length];
        fileSpecification.Contents.Read(fileContent, 0, fileContent.Length);
        using var fileStream = new FileStream(dataDir + count + "_out" + ".txt", FileMode.Create);
        fileStream.Write(fileContent, 0, fileContent.Length);

        count += 1;
    }
}

获取单个附件

为了获取单个附件，我们可以指定 Document 实例的 EmbeddedFiles 对象中的附件索引。请尝试使用以下代码片段。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetIndividualAttachment()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Attachments();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "GetIndividualAttachment.pdf"))
    {
        // Get particular embedded file
        Aspose.Pdf.FileSpecification fileSpecification = document.EmbeddedFiles[1];

        // Get the file properties
        Console.WriteLine("Name: {0}", fileSpecification.Name);
        Console.WriteLine("Description: {0}", fileSpecification.Description);
        Console.WriteLine("Mime Type: {0}", fileSpecification.MIMEType);

        // Check if parameter object contains the parameters
        if (fileSpecification.Params != null)
        {
            Console.WriteLine("CheckSum: {0}",
            fileSpecification.Params.CheckSum);
            Console.WriteLine("Creation Date: {0}",
            fileSpecification.Params.CreationDate);
            Console.WriteLine("Modification Date: {0}",
            fileSpecification.Params.ModDate);
            Console.WriteLine("Size: {0}", fileSpecification.Params.Size);
        }

        // Get the attachment and write to file or stream
        var fileContent = new byte[fileSpecification.Contents.Length];
        fileSpecification.Contents.Read(fileContent, 0, fileContent.Length);

        using (var fileStream = new FileStream(dataDir + "test_out" + ".txt", FileMode.Create))
        {
            fileStream.Write(fileContent, 0, fileContent.Length);
        }
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetIndividualAttachment()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Attachments();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "GetIndividualAttachment.pdf");

    // Get particular embedded file
    Aspose.Pdf.FileSpecification fileSpecification = document.EmbeddedFiles[1];

    // Get the file properties
    Console.WriteLine("Name: {0}", fileSpecification.Name);
    Console.WriteLine("Description: {0}", fileSpecification.Description);
    Console.WriteLine("Mime Type: {0}", fileSpecification.MIMEType);

    // Check if parameter object contains the parameters
    if (fileSpecification.Params != null)
    {
        Console.WriteLine("CheckSum: {0}",
        fileSpecification.Params.CheckSum);
        Console.WriteLine("Creation Date: {0}",
        fileSpecification.Params.CreationDate);
        Console.WriteLine("Modification Date: {0}",
        fileSpecification.Params.ModDate);
        Console.WriteLine("Size: {0}", fileSpecification.Params.Size);
    }

    // Get the attachment and write to file or stream
    var fileContent = new byte[fileSpecification.Contents.Length];
    fileSpecification.Contents.Read(fileContent, 0, fileContent.Length);

    using var fileStream = new FileStream(dataDir + "test_out" + ".txt", FileMode.Create);
    fileStream.Write(fileContent, 0, fileContent.Length);
}

获取包含在 FileAttachmentAnnotation 对象中的附件

除了 Document 对象的 EmbeddedFiles 集合外，附件还可以包含在 FileAttachmentAnnotation 对象中。以下是查看此类附件的数量和详细信息的代码。

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ViewAttachmentsInFileAttachmentAnnotations()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Attachments();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "GetAlltheAttachments.pdf"))
    {
        for (int i = 1; i <= document.Pages.Count; i++)
        {
            foreach (Aspose.Pdf.Annotations.Annotation annotation in document.Pages[i].Annotations)
            {
                var fileAttachmentAnnotation = annotation as Aspose.Pdf.Annotations.FileAttachmentAnnotation;
                if (fileAttachmentAnnotation != null)
                {
                    Aspose.Pdf.FileSpecification file = fileAttachmentAnnotation.File;
                    if (file != null && file.Name != null)
                    {
                        Console.WriteLine($"Name: {file.Name} on page {i}");
                    }
                }
            }
        }
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ViewAttachmentsInFileAttachmentAnnotations()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Attachments();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "GetAlltheAttachments.pdf");

    for (int i = 1; i <= document.Pages.Count; i++)
    {
        foreach (Aspose.Pdf.Annotations.Annotation annotation in document.Pages[i].Annotations)
        {
            var fileAttachmentAnnotation = annotation as Aspose.Pdf.Annotations.FileAttachmentAnnotation;
            if (fileAttachmentAnnotation != null)
            {
                Aspose.Pdf.FileSpecification file = fileAttachmentAnnotation.File;
                if (file != null && file.Name != null)
                {
                    Console.WriteLine($"Name: {file.Name} on page {i}");
                }
            }
        }
    }
}