使用OpenXmlPowerTools DocumentBuilder合并文档如何实现分页？

问题背景 #

使用OpenXmlPowerTools的DocumentBuilder合并DOCX文档时，第二个文档直接追加在第一个文档末尾，需要实现新页分隔；尝试Open XML原生AltChunk方式会导致第二个文档格式丢失。

原合并代码 #

public void DocMerger()
{
    var source1 = Server.MapPath(Url.Content("~/1.docx")); //source 1
    var source2 = Server.MapPath(Url.Content("~/2.docx")); //source 2
   
    var merged = Server.MapPath(Url.Content("~/App_Data/merged.docx")); //merged

    var f1 = new FileInfo(source1);
    var f2 = new FileInfo(source2);
  

    //Use DocumentBuilder and merge the files
    var sources = new List<OpenXmlPowerTools.Source>()
    {
        new Source(new WmlDocument(f1.FullName),true),
          new Source(new WmlDocument(f2.FullName),true),
        
    };
    var mergedDocument = DocumentBuilder.BuildDocument(sources);
    mergedDocument.SaveAs(merged); //save merged data as merged.docx

}

尝试过的AltChunk代码（格式丢失） #

using (WordprocessingDocument myDoc = WordprocessingDocument.Open("D:\Test.docx", true))
{
    string altChunkId = "AltChunkId" + DateTime.Now.Ticks.ToString().Substring(0, 2) ;
    MainDocumentPart mainPart = myDoc.MainDocumentPart;
    AlternativeFormatImportPart chunk = mainPart.AddAlternativeFormatImportPart(
        AlternativeFormatImportPartType.WordprocessingML, altChunkId);
    using (FileStream fileStream = File.Open("D:\Test1.docx", FileMode.Open))
        chunk.FeedData(fileStream);
    AltChunk altChunk = new AltChunk();
    altChunk.Id = altChunkId;
    mainPart.Document
        .Body
        .InsertAfter(altChunk, mainPart.Document.Body.Elements<Paragraph>().Last());
    mainPart.Document.Save();
} 

可行解决方案 #

以下两种方案均基于OpenXmlPowerTools合并逻辑，可完整保留原文档格式，实现新页分隔：

方案1：在第一个文档末尾添加分页符 #

合并前修改第一个文档，在其Body末尾插入带有分页属性的段落，强制后续内容从新页开始：

public void DocMerger()
{
    var source1 = Server.MapPath(Url.Content("~/1.docx"));
    var source2 = Server.MapPath(Url.Content("~/2.docx"));
    var merged = Server.MapPath(Url.Content("~/App_Data/merged.docx"));

    // 加载第一个文档并添加分页符
    var doc1 = new WmlDocument(source1);
    using (var memoryStream = new MemoryStream())
    {
        doc1.WriteToStream(memoryStream);
        using (var wordDoc = WordprocessingDocument.Open(memoryStream, true))
        {
            var body = wordDoc.MainDocumentPart.Document.Body;
            
            // 创建带分页符的段落
            var pageBreakPara = new Paragraph(
                new ParagraphProperties(
                    new SectionProperties(
                        new PageBreakBefore()
                    )
                )
            );
            
            body.Append(pageBreakPara);
            wordDoc.Save();
        }
        doc1 = new WmlDocument(memoryStream);
    }

    // 执行合并
    var sources = new List<OpenXmlPowerTools.Source>()
    {
        new Source(doc1, true),
        new Source(new WmlDocument(source2), true),
    };

    var mergedDocument = DocumentBuilder.BuildDocument(sources);
    mergedDocument.SaveAs(merged);
}

方案2：在第二个文档开头添加分页符 #

若不想修改第一个文档，可在第二个文档的起始位置插入分页段落：

public void DocMerger()
{
    var source1 = Server.MapPath(Url.Content("~/1.docx"));
    var source2 = Server.MapPath(Url.Content("~/2.docx"));
    var merged = Server.MapPath(Url.Content("~/App_Data/merged.docx"));

    // 加载第二个文档并在开头添加分页符
    var doc2 = new WmlDocument(source2);
    using (var memoryStream = new MemoryStream())
    {
        doc2.WriteToStream(memoryStream);
        using (var wordDoc = WordprocessingDocument.Open(memoryStream, true))
        {
            var body = wordDoc.MainDocumentPart.Document.Body;
            
            // 创建带分页符的段落并插入到最前面
            var pageBreakPara = new Paragraph(
                new ParagraphProperties(
                    new SectionProperties(
                        new PageBreakBefore()
                    )
                )
            );
            
            body.InsertAt(pageBreakPara, 0);
            wordDoc.Save();
        }
        doc2 = new WmlDocument(memoryStream);
    }

    // 执行合并
    var sources = new List<OpenXmlPowerTools.Source>()
    {
        new Source(new WmlDocument(source1), true),
        new Source(doc2, true),
    };

    var mergedDocument = DocumentBuilder.BuildDocument(sources);
    mergedDocument.SaveAs(merged);
}

方案说明 #

• 两种方案都通过PageBreakBefore属性实现强制分页，完全基于OpenXmlPowerTools的合并逻辑，避免AltChunk的格式丢失问题
• 可根据实际需求选择修改第一个或第二个文档的方式

内容的提问来源于stack exchange，提问作者Rams