impl migration to pdfium for split (#6410)

## Summary Migrates `SplitPDFController`, `SplitPdfByChaptersController`, `SplitPdfBySizeController` from PDFBox to JPDFium. `SplitPdfBySectionsController` and `AutoSplitPdfController` are intentionally left on PDFBox (require JPDFium 1.0.2 features that don't exist yet). ## Benchmark (audited on `audit/jpdfium-split`, file `app/core/src/test/java/stirling/software/SPDF/bench/SplitBenchmark.java`) | Workload | PDFBox heap | JPDFium heap | PDFBox wall | JPDFium wall | |---|---|---|---|---| | 100 pp, chunk 10 | +21-26 MB | **+0.02 MB** | 80-106 ms | **25 ms** | | 300 pp, chunk 10 | +59 MB | **+1.0 MB** | 232 ms | **76 ms** | **98-99.9% heap reduction. 3-4.2x faster wall.** ## Hybrid - AcroForm-bearing splits keep PDFBox `FormUtils.pruneOrphanedFormFields` post-pass (FPDF_ImportPagesByIndex drops AcroForm dict). Sub-bench shows +1.0 MB / +27 ms - tightly bounded. - Metadata extraction stays on PDFBox. - `SplitPdfBySectionsController` - JPDFium `PdfPageSplitter` only does 2-up halving, not arbitrary MxN. - `AutoSplitPdfController` - needs PDFRenderer + zxing for QR markers. ## Test plan - [ ] 30/30 unit tests pass with PDFBox `Loader.loadPDF` as the oracle (assert page counts + document totals) - [ ] Existing cucumber feature `split.feature` continues to pass - [ ] AcroForm-bearing PDF round-trips without orphaned widgets (covered by existing FormUtils tests)
2026-07-16 19:33:11 +02:00 · 2026-05-26 17:50:13 +01:00
parent 05b80fbe4f
commit 56ff1e5092
15 changed files with 762 additions and 395 deletions
@@ -3,6 +3,7 @@ package stirling.software.SPDF.controller.api;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -30,12 +31,13 @@ import stirling.software.common.annotations.AutoJobPostMapping;
 import stirling.software.common.annotations.api.GeneralApi;
 import stirling.software.common.enumeration.ResourceWeight;
 import stirling.software.common.service.CustomPDFDocumentFactory;
-import stirling.software.common.util.ExceptionUtils;
 import stirling.software.common.util.FormUtils;
 import stirling.software.common.util.GeneralUtils;
 import stirling.software.common.util.TempFile;
 import stirling.software.common.util.TempFileManager;
 import stirling.software.common.util.WebResponseUtils;
+import stirling.software.jpdfium.PdfDocument;
+import stirling.software.jpdfium.PdfSplit;

@GeneralApi
@Slf4j
@@ -91,10 +93,14 @@ public class SplitPDFController {
                try (ZipOutputStream zipOut =
                        new ZipOutputStream(Files.newOutputStream(outputTempFile.getPath()))) {
                    if (hasForm) {
-                        writeSplitsViaReload(
+                        // JPDFium's FPDF_ImportPagesByIndex drops the AcroForm dictionary, which
+                        // breaks Fill Forms downstream. Fall back to the PDFBox load-and-remove
+                        // path so the AcroForm (with only fields whose widgets remain on kept
+                        // pages) is preserved.
+                        writeSplitsViaPdfBox(
                                sourceTempFile.getFile(), pageNumbers, baseFilename, zipOut);
                    } else {
-                        writeSplitsViaSharedSource(
+                        writeSplitsViaJpdfium(
                                sourceTempFile.getFile(), pageNumbers, baseFilename, zipOut);
                    }
                }
@@ -109,7 +115,26 @@ public class SplitPDFController {
        }
    }

-    private void writeSplitsViaReload(
+    private void writeSplitsViaJpdfium(
+            File source, List<Integer> pageNumbers, String baseFilename, ZipOutputStream zipOut)
+            throws IOException {
+        try (PdfDocument sourceDoc = PdfDocument.open(source.toPath())) {
+            int previousPageNumber = 0;
+            for (int splitIndex = 0; splitIndex < pageNumbers.size(); splitIndex++) {
+                int splitPoint = pageNumbers.get(splitIndex);
+                try (TempFile splitTemp = new TempFile(tempFileManager, ".pdf")) {
+                    try (PdfDocument splitDoc =
+                            PdfSplit.extractPageRange(sourceDoc, previousPageNumber, splitPoint)) {
+                        splitDoc.save(splitTemp.getPath());
+                    }
+                    writeEntry(zipOut, baseFilename, splitIndex + 1, splitTemp.getPath());
+                }
+                previousPageNumber = splitPoint + 1;
+            }
+        }
+    }
+
+    private void writeSplitsViaPdfBox(
            File source, List<Integer> pageNumbers, String baseFilename, ZipOutputStream zipOut)
            throws IOException {
        int previousPageNumber = 0;
@@ -129,33 +154,15 @@ public class SplitPDFController {
                }
                FormUtils.pruneOrphanedFormFields(splitDoc);
                writeEntry(zipOut, baseFilename, splitIndex + 1, splitDoc);
-            } catch (Exception e) {
-                ExceptionUtils.logException("document splitting and saving", e);
-                throw e;
            }
        }
    }

-    private void writeSplitsViaSharedSource(
-            File source, List<Integer> pageNumbers, String baseFilename, ZipOutputStream zipOut)
+    private void writeEntry(ZipOutputStream zipOut, String baseFilename, int index, Path pdfPath)
            throws IOException {
-        try (PDDocument sourceDoc = pdfDocumentFactory.load(source)) {
-            int previousPageNumber = 0;
-            for (int splitIndex = 0; splitIndex < pageNumbers.size(); splitIndex++) {
-                int splitPoint = pageNumbers.get(splitIndex);
-                try (PDDocument splitDoc =
-                        pdfDocumentFactory.createNewDocumentBasedOnOldDocument(sourceDoc)) {
-                    for (int i = previousPageNumber; i <= splitPoint; i++) {
-                        splitDoc.addPage(sourceDoc.getPage(i));
-                    }
-                    previousPageNumber = splitPoint + 1;
-                    writeEntry(zipOut, baseFilename, splitIndex + 1, splitDoc);
-                } catch (Exception e) {
-                    ExceptionUtils.logException("document splitting and saving", e);
-                    throw e;
-                }
-            }
-        }
+        zipOut.putNextEntry(new ZipEntry(baseFilename + "_" + index + ".pdf"));
+        Files.copy(pdfPath, zipOut);
+        zipOut.closeEntry();
    }

    private void writeEntry(ZipOutputStream zipOut, String baseFilename, int index, PDDocument doc)
@@ -1,6 +1,10 @@
 package stirling.software.SPDF.controller.api;

+import java.io.File;
+import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
@@ -8,9 +12,7 @@ import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;

 import org.apache.pdfbox.pdmodel.PDDocument;
-import org.apache.pdfbox.pdmodel.PDPage;
-import org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline.PDDocumentOutline;
-import org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline.PDOutlineItem;
+import org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm;
 import org.springframework.core.io.Resource;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
@@ -35,10 +37,13 @@ import stirling.software.common.model.PdfMetadata;
 import stirling.software.common.service.CustomPDFDocumentFactory;
 import stirling.software.common.service.PdfMetadataService;
 import stirling.software.common.util.ExceptionUtils;
+import stirling.software.common.util.FormUtils;
 import stirling.software.common.util.GeneralUtils;
 import stirling.software.common.util.TempFile;
 import stirling.software.common.util.TempFileManager;
 import stirling.software.common.util.WebResponseUtils;
+import stirling.software.jpdfium.PdfDocument;
+import stirling.software.jpdfium.PdfSplit;

@GeneralApi
@Slf4j
@@ -51,72 +56,36 @@ public class SplitPdfByChaptersController {

    private final TempFileManager tempFileManager;

-    private static List<Bookmark> extractOutlineItems(
-            PDDocument sourceDocument,
-            PDOutlineItem current,
-            List<Bookmark> bookmarks,
-            PDOutlineItem nextParent,
+    private static void collectBookmarks(
+            List<stirling.software.jpdfium.doc.Bookmark> source,
+            List<Bookmark> out,
            int level,
-            int maxLevel)
-            throws Exception {
-
-        while (current != null) {
-
-            String currentTitle = current.getTitle().replace("/", "");
-            int firstPage =
-                    sourceDocument.getPages().indexOf(current.findDestinationPage(sourceDocument));
-            PDOutlineItem child = current.getFirstChild();
-            PDOutlineItem nextSibling = current.getNextSibling();
-            int endPage;
-            if (child != null && level < maxLevel) {
-                endPage =
-                        sourceDocument
-                                .getPages()
-                                .indexOf(child.findDestinationPage(sourceDocument));
-            } else if (nextSibling != null) {
-                endPage =
-                        sourceDocument
-                                .getPages()
-                                .indexOf(nextSibling.findDestinationPage(sourceDocument));
-            } else if (nextParent != null) {
-
-                endPage =
-                        sourceDocument
-                                .getPages()
-                                .indexOf(nextParent.findDestinationPage(sourceDocument));
-            } else {
-                endPage = -2;
-                /*
-                happens when we have something like this:
-                Outline Item 2
-                    Outline Item 2.1
-                        Outline Item 2.1.1
-                    Outline Item 2.2
-                        Outline 2.2.1
-                        Outline 2.2.2 <--- this item neither has an immediate next parent nor an immediate next sibling
-                Outline Item 3
-                 */
+            int maxLevel) {
+        for (stirling.software.jpdfium.doc.Bookmark bm : source) {
+            if (!bm.isInternal()) {
+                continue;
            }
-            if (!bookmarks.isEmpty()
-                    && bookmarks.get(bookmarks.size() - 1).getEndPage() == -2
-                    && firstPage
-                            >= bookmarks
-                                    .get(bookmarks.size() - 1)
-                                    .getStartPage()) { // for handling the above-mentioned case
-                Bookmark previousBookmark = bookmarks.get(bookmarks.size() - 1);
-                previousBookmark.setEndPage(firstPage);
+            String title = bm.title() == null ? "" : bm.title().replace("/", "");
+            int firstPage = Math.max(0, bm.pageIndex());
+            out.add(new Bookmark(title, firstPage, -2));
+            if (bm.hasChildren() && level < maxLevel) {
+                collectBookmarks(bm.children(), out, level + 1, maxLevel);
            }
-            bookmarks.add(new Bookmark(currentTitle, firstPage, endPage));
-
-            // Recursively process children
-            if (child != null && level < maxLevel) {
-                extractOutlineItems(
-                        sourceDocument, child, bookmarks, nextSibling, level + 1, maxLevel);
-            }
-
-            current = nextSibling;
        }
-        return bookmarks;
+    }
+
+    private static void assignEndPages(List<Bookmark> bookmarks, int totalPages) {
+        for (int i = 0; i < bookmarks.size(); i++) {
+            Bookmark current = bookmarks.get(i);
+            int next = -1;
+            for (int j = i + 1; j < bookmarks.size(); j++) {
+                if (bookmarks.get(j).getStartPage() >= current.getStartPage()) {
+                    next = bookmarks.get(j).getStartPage();
+                    break;
+                }
+            }
+            current.setEndPage(next == -1 ? totalPages : next);
+        }
    }

    @AutoJobPostMapping(
@@ -134,46 +103,41 @@ public class SplitPdfByChaptersController {
        MultipartFile file = request.getFileInput();

        boolean includeMetadata = Boolean.TRUE.equals(request.getIncludeMetadata());
-        Integer bookmarkLevel =
-                request.getBookmarkLevel(); // levels start from 0 (top most bookmarks)
+        Integer bookmarkLevel = request.getBookmarkLevel();
        if (bookmarkLevel < 0) {
            throw ExceptionUtils.createIllegalArgumentException(
                    "error.invalidArgument", "Invalid argument: {0}", "bookmark level");
        }

-        try (PDDocument sourceDocument = pdfDocumentFactory.load(file)) {
-            PDDocumentOutline outline = sourceDocument.getDocumentCatalog().getDocumentOutline();
+        try (TempFile sourceTempFile = new TempFile(tempFileManager, ".pdf")) {
+            Files.copy(
+                    file.getInputStream(),
+                    sourceTempFile.getPath(),
+                    StandardCopyOption.REPLACE_EXISTING);

-            if (outline == null) {
-                log.warn("No outline found for {}", file.getOriginalFilename());
-                throw ExceptionUtils.createIllegalArgumentException(
-                        "error.pdfBookmarksNotFound", "No PDF bookmarks/outline found in document");
-            }
            List<Bookmark> bookmarks = new ArrayList<>();
-            try {
-                bookmarks =
-                        extractOutlineItems(
-                                sourceDocument,
-                                outline.getFirstChild(),
-                                bookmarks,
-                                outline.getFirstChild().getNextSibling(),
-                                0,
-                                bookmarkLevel);
-                // to handle last page edge case
-                bookmarks.get(bookmarks.size() - 1).setEndPage(sourceDocument.getNumberOfPages());
-
-            } catch (Exception e) {
-                ExceptionUtils.logException("outline extraction", e);
-                throw e;
+            int totalPages;
+            try (PdfDocument sourceDocument = PdfDocument.open(sourceTempFile.getPath())) {
+                totalPages = sourceDocument.pageCount();
+                List<stirling.software.jpdfium.doc.Bookmark> roots = sourceDocument.bookmarks();
+                if (roots == null || roots.isEmpty()) {
+                    log.warn("No outline found for {}", file.getOriginalFilename());
+                    throw ExceptionUtils.createIllegalArgumentException(
+                            "error.pdfBookmarksNotFound",
+                            "No PDF bookmarks/outline found in document");
+                }
+                collectBookmarks(roots, bookmarks, 0, bookmarkLevel);
+                if (bookmarks.isEmpty()) {
+                    log.warn("No outline found for {}", file.getOriginalFilename());
+                    throw ExceptionUtils.createIllegalArgumentException(
+                            "error.pdfBookmarksNotFound",
+                            "No PDF bookmarks/outline found in document");
+                }
+                assignEndPages(bookmarks, totalPages);
            }

            boolean allowDuplicates = Boolean.TRUE.equals(request.getAllowDuplicates());
            if (!allowDuplicates) {
-                /*
-                duplicates are generated when multiple bookmarks correspond to the same page,
-                if the user doesn't want duplicates mergeBookmarksThatCorrespondToSamePage() method will merge the titles of all
-                the bookmarks that correspond to the same page, and treat them as a single bookmark
-                */
                bookmarks = mergeBookmarksThatCorrespondToSamePage(bookmarks);
            }
            for (Bookmark bookmark : bookmarks) {
@@ -184,7 +148,23 @@ public class SplitPdfByChaptersController {
                        bookmark.getEndPage());
            }

-            TempFile zipTempFile = createZipFile(sourceDocument, bookmarks, includeMetadata);
+            PdfMetadata metadata = null;
+            boolean hasForm = false;
+            if (includeMetadata) {
+                try (PDDocument metaDoc = pdfDocumentFactory.load(sourceTempFile.getFile())) {
+                    metadata = pdfMetadataService.extractMetadataFromPdf(metaDoc);
+                    PDAcroForm acroForm = metaDoc.getDocumentCatalog().getAcroForm(null);
+                    hasForm = acroForm != null;
+                }
+            } else {
+                try (PDDocument acroDoc = pdfDocumentFactory.load(sourceTempFile.getFile(), true)) {
+                    hasForm = acroDoc.getDocumentCatalog().getAcroForm(null) != null;
+                }
+            }
+
+            TempFile zipTempFile =
+                    createZipFile(
+                            sourceTempFile.getFile(), bookmarks, metadata, totalPages, hasForm);
            String filename = GeneralUtils.generateFilename(file.getOriginalFilename(), "");
            return WebResponseUtils.zipFileToWebResponse(zipTempFile, filename + ".zip");
        }
@@ -216,43 +196,40 @@ public class SplitPdfByChaptersController {
    }

    private TempFile createZipFile(
-            PDDocument sourceDocument, List<Bookmark> bookmarks, boolean includeMetadata)
+            File sourceFile,
+            List<Bookmark> bookmarks,
+            PdfMetadata metadata,
+            int totalPages,
+            boolean hasForm)
            throws Exception {
-        PdfMetadata metadata =
-                includeMetadata ? pdfMetadataService.extractMetadataFromPdf(sourceDocument) : null;
        String fileNumberFormatter = "%0" + (Integer.toString(bookmarks.size()).length()) + "d ";
        TempFile zipTempFile = new TempFile(tempFileManager, ".zip");
-        try {
-            try (ZipOutputStream zipOut =
-                    new ZipOutputStream(Files.newOutputStream(zipTempFile.getPath()))) {
+        try (ZipOutputStream zipOut =
+                new ZipOutputStream(Files.newOutputStream(zipTempFile.getPath()))) {
+            if (hasForm) {
+                // JPDFium's FPDF_ImportPagesByIndex drops the AcroForm dictionary. For form
+                // PDFs, do the per-chapter extract via PDFBox so form fields survive the split.
                for (int i = 0; i < bookmarks.size(); i++) {
-                    Bookmark bookmark = bookmarks.get(i);
-                    try (PDDocument splitDocument = new PDDocument()) {
-                        boolean isSinglePage = (bookmark.getStartPage() == bookmark.getEndPage());
-
-                        for (int pg = bookmark.getStartPage();
-                                pg < bookmark.getEndPage() + (isSinglePage ? 1 : 0);
-                                pg++) {
-                            PDPage page = sourceDocument.getPage(pg);
-                            splitDocument.addPage(page);
-                            log.debug("Adding page {} to split document", pg);
-                        }
-                        if (includeMetadata) {
-                            pdfMetadataService.setMetadataToPdf(splitDocument, metadata);
-                        }
-
-                        // split files will be named as "[FILE_NUMBER] [BOOKMARK_TITLE].pdf"
-                        String fileName =
-                                String.format(Locale.ROOT, fileNumberFormatter, i)
-                                        + bookmark.getTitle()
-                                        + ".pdf";
-                        zipOut.putNextEntry(new ZipEntry(fileName));
-                        splitDocument.save(zipOut);
-                        zipOut.closeEntry();
-                        log.debug("Wrote split document {} to zip file", fileName);
-                    } catch (Exception e) {
-                        ExceptionUtils.logException("document splitting and saving", e);
-                        throw e;
+                    writeChapterViaPdfBox(
+                            sourceFile,
+                            bookmarks.get(i),
+                            i,
+                            fileNumberFormatter,
+                            metadata,
+                            zipOut,
+                            totalPages);
+                }
+            } else {
+                try (PdfDocument sourceDocument = PdfDocument.open(sourceFile.toPath())) {
+                    for (int i = 0; i < bookmarks.size(); i++) {
+                        writeChapterViaJpdfium(
+                                sourceDocument,
+                                bookmarks.get(i),
+                                i,
+                                fileNumberFormatter,
+                                metadata,
+                                zipOut,
+                                totalPages);
                    }
                }
            }
@@ -265,6 +242,97 @@ public class SplitPdfByChaptersController {
            throw e;
        }
    }
+
+    private void writeChapterViaJpdfium(
+            PdfDocument sourceDocument,
+            Bookmark bookmark,
+            int index,
+            String fileNumberFormatter,
+            PdfMetadata metadata,
+            ZipOutputStream zipOut,
+            int totalPages)
+            throws Exception {
+        int[] range = clampRange(bookmark, totalPages);
+        int from = range[0];
+        int to = range[1];
+        try (TempFile splitTemp = new TempFile(tempFileManager, ".pdf")) {
+            try (PdfDocument splitDoc = PdfSplit.extractPageRange(sourceDocument, from, to)) {
+                splitDoc.save(splitTemp.getPath());
+            }
+            Path finalPath = splitTemp.getPath();
+            TempFile metaTemp = null;
+            try {
+                if (metadata != null) {
+                    metaTemp = new TempFile(tempFileManager, ".pdf");
+                    try (PDDocument doc = pdfDocumentFactory.load(splitTemp.getFile())) {
+                        pdfMetadataService.setMetadataToPdf(doc, metadata);
+                        doc.save(metaTemp.getFile());
+                    }
+                    finalPath = metaTemp.getPath();
+                }
+                writeZipEntry(zipOut, fileNumberFormatter, index, bookmark.getTitle(), finalPath);
+            } finally {
+                if (metaTemp != null) {
+                    metaTemp.close();
+                }
+            }
+        }
+    }
+
+    private void writeChapterViaPdfBox(
+            File sourceFile,
+            Bookmark bookmark,
+            int index,
+            String fileNumberFormatter,
+            PdfMetadata metadata,
+            ZipOutputStream zipOut,
+            int totalPages)
+            throws Exception {
+        int[] range = clampRange(bookmark, totalPages);
+        int from = range[0];
+        int to = range[1];
+        try (PDDocument doc = pdfDocumentFactory.load(sourceFile)) {
+            for (int p = doc.getNumberOfPages() - 1; p >= 0; p--) {
+                if (p < from || p > to) {
+                    doc.removePage(p);
+                }
+            }
+            FormUtils.pruneOrphanedFormFields(doc);
+            if (metadata != null) {
+                pdfMetadataService.setMetadataToPdf(doc, metadata);
+            }
+            String fileName =
+                    String.format(Locale.ROOT, fileNumberFormatter, index)
+                            + bookmark.getTitle()
+                            + ".pdf";
+            zipOut.putNextEntry(new ZipEntry(fileName));
+            doc.save(zipOut);
+            zipOut.closeEntry();
+            log.debug("Wrote split document {} to zip file", fileName);
+        }
+    }
+
+    private void writeZipEntry(
+            ZipOutputStream zipOut,
+            String fileNumberFormatter,
+            int index,
+            String title,
+            Path pdfPath)
+            throws IOException {
+        String fileName = String.format(Locale.ROOT, fileNumberFormatter, index) + title + ".pdf";
+        zipOut.putNextEntry(new ZipEntry(fileName));
+        Files.copy(pdfPath, zipOut);
+        zipOut.closeEntry();
+        log.debug("Wrote split document {} to zip file", fileName);
+    }
+
+    private static int[] clampRange(Bookmark bookmark, int totalPages) {
+        boolean isSinglePage = bookmark.getStartPage() == bookmark.getEndPage();
+        int from = Math.min(Math.max(0, bookmark.getStartPage()), totalPages - 1);
+        int rawEnd = isSinglePage ? bookmark.getEndPage() : bookmark.getEndPage() - 1;
+        int to = Math.min(Math.max(from, rawEnd), totalPages - 1);
+        return new int[] {from, to};
+    }
 }

@Data
@@ -1,9 +1,9 @@
 package stirling.software.SPDF.controller.api;

-import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -13,7 +13,6 @@ import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;

 import org.apache.pdfbox.pdmodel.PDDocument;
-import org.apache.pdfbox.pdmodel.PDPage;
 import org.springframework.core.io.Resource;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
@@ -37,6 +36,8 @@ import stirling.software.common.util.GeneralUtils;
 import stirling.software.common.util.TempFile;
 import stirling.software.common.util.TempFileManager;
 import stirling.software.common.util.WebResponseUtils;
+import stirling.software.jpdfium.PdfDocument;
+import stirling.software.jpdfium.PdfSplit;

@GeneralApi
@Slf4j
@@ -75,23 +76,27 @@ public class SplitPdfBySizeController {
                        sourceTempFile.getPath(),
                        StandardCopyOption.REPLACE_EXISTING);

-                try (PDDocument sourceDocument =
-                        pdfDocumentFactory.load(sourceTempFile.getFile(), true)) {
-                    boolean hasForm = sourceDocument.getDocumentCatalog().getAcroForm(null) != null;
-                    List<List<Integer>> ranges = computeRanges(request, sourceDocument);
+                boolean hasForm;
+                try (PDDocument acroDoc = pdfDocumentFactory.load(sourceTempFile.getFile(), true)) {
+                    hasForm = acroDoc.getDocumentCatalog().getAcroForm(null) != null;
+                }
+
+                try (PdfDocument sourceDocument = PdfDocument.open(sourceTempFile.getPath())) {
+                    List<int[]> ranges = computeRanges(request, sourceDocument);

                    int fileIndex = 1;
-                    for (List<Integer> range : ranges) {
-                        if (range.isEmpty()) {
+                    for (int[] range : ranges) {
+                        if (range.length == 0) {
                            continue;
                        }
-                        if (hasForm) {
-                            writeRangeViaReload(
-                                    sourceTempFile.getFile(), range, zipOut, filename, fileIndex++);
-                        } else {
-                            writeRangeViaSharedSource(
-                                    sourceDocument, range, zipOut, filename, fileIndex++);
-                        }
+                        writeRange(
+                                sourceDocument,
+                                sourceTempFile.getFile(),
+                                range,
+                                zipOut,
+                                filename,
+                                fileIndex++,
+                                hasForm);
                    }
                }
            }
@@ -104,29 +109,54 @@ public class SplitPdfBySizeController {
        }
    }

-    private List<List<Integer>> computeRanges(
-            SplitPdfBySizeOrCountRequest request, PDDocument sourceDocument) throws IOException {
+    private List<int[]> computeRanges(SplitPdfBySizeOrCountRequest request, PdfDocument sourceDoc)
+            throws IOException {
        int type = request.getSplitType();
        String value = request.getSplitValue();
        if (type == 0) {
-            return computeSizeRanges(sourceDocument, GeneralUtils.convertSizeToBytes(value));
+            return computeSizeRanges(sourceDoc, GeneralUtils.convertSizeToBytes(value));
        } else if (type == 1) {
-            return computePageCountRanges(sourceDocument, Integer.parseInt(value));
+            return computePageCountRanges(sourceDoc, Integer.parseInt(value));
        } else if (type == 2) {
-            return computeDocCountRanges(sourceDocument, Integer.parseInt(value));
+            return computeDocCountRanges(sourceDoc, Integer.parseInt(value));
        }
        throw ExceptionUtils.createIllegalArgumentException(
                "error.invalidArgument", "Invalid argument: {0}", "split type: " + type);
    }

-    private void writeRangeViaReload(
+    private void writeRange(
+            PdfDocument sourceDoc,
            File sourceFile,
-            List<Integer> keepIndices,
+            int[] range,
+            ZipOutputStream zipOut,
+            String baseFilename,
+            int fileIndex,
+            boolean hasForm)
+            throws IOException {
+        if (hasForm) {
+            // JPDFium's FPDF_ImportPagesByIndex drops the AcroForm dictionary, breaking form
+            // fields downstream. For form-bearing PDFs, do the extract via PDFBox so the
+            // AcroForm survives (pruneOrphanedFormFields removes references to dropped pages).
+            writeRangeViaPdfBox(sourceFile, range, zipOut, baseFilename, fileIndex);
+        } else {
+            try (TempFile splitTemp = new TempFile(tempFileManager, ".pdf")) {
+                extractRangeToFile(sourceDoc, range, splitTemp.getPath());
+                writeEntry(zipOut, baseFilename, fileIndex, splitTemp.getPath());
+            }
+        }
+    }
+
+    private void writeRangeViaPdfBox(
+            File sourceFile,
+            int[] range,
            ZipOutputStream zipOut,
            String baseFilename,
            int fileIndex)
            throws IOException {
-        Set<Integer> keep = new HashSet<>(keepIndices);
+        Set<Integer> keep = new HashSet<>();
+        for (int p : range) {
+            keep.add(p);
+        }
        try (PDDocument doc = pdfDocumentFactory.load(sourceFile)) {
            for (int i = doc.getNumberOfPages() - 1; i >= 0; i--) {
                if (!keep.contains(i)) {
@@ -134,50 +164,41 @@ public class SplitPdfBySizeController {
                }
            }
            FormUtils.pruneOrphanedFormFields(doc);
-            writeEntry(zipOut, baseFilename, fileIndex, doc);
+            zipOut.putNextEntry(new ZipEntry(baseFilename + "_" + fileIndex + ".pdf"));
+            doc.save(zipOut);
+            zipOut.closeEntry();
        }
    }

-    private void writeRangeViaSharedSource(
-            PDDocument sourceDocument,
-            List<Integer> keepIndices,
-            ZipOutputStream zipOut,
-            String baseFilename,
-            int fileIndex)
+    private void extractRangeToFile(PdfDocument sourceDoc, int[] range, Path outputPath)
            throws IOException {
-        try (PDDocument doc =
-                pdfDocumentFactory.createNewDocumentBasedOnOldDocument(sourceDocument)) {
-            for (int p : keepIndices) {
-                doc.addPage(sourceDocument.getPage(p));
-            }
-            writeEntry(zipOut, baseFilename, fileIndex, doc);
+        int from = range[0];
+        int to = range[range.length - 1];
+        try (PdfDocument split = PdfSplit.extractPageRange(sourceDoc, from, to)) {
+            split.save(outputPath);
        }
    }

    private void writeEntry(
-            ZipOutputStream zipOut, String baseFilename, int fileIndex, PDDocument doc)
+            ZipOutputStream zipOut, String baseFilename, int fileIndex, Path pdfPath)
            throws IOException {
        zipOut.putNextEntry(new ZipEntry(baseFilename + "_" + fileIndex + ".pdf"));
-        doc.save(zipOut);
+        Files.copy(pdfPath, zipOut);
        zipOut.closeEntry();
    }

-    /** Page-index ranges each output should contain. AcroForm overhead isn't modeled. */
-    private List<List<Integer>> computeSizeRanges(PDDocument sourceDocument, long maxBytes)
-            throws IOException {
-        List<List<Integer>> ranges = new ArrayList<>();
-        List<Integer> currentRange = new ArrayList<>();
-        int totalPages = sourceDocument.getNumberOfPages();
+    /** Returns contiguous page-index ranges fitting within {@code maxBytes}. */
+    private List<int[]> computeSizeRanges(PdfDocument sourceDoc, long maxBytes) throws IOException {
+        List<int[]> ranges = new ArrayList<>();
+        int totalPages = sourceDoc.pageCount();
        int baseCheckFrequency = 5;
-
-        PDDocument scratch = new PDDocument();
-        try {
+        int rangeStart = 0;
+        int rangeEnd = -1;
+        try (TempFile probe = new TempFile(tempFileManager, ".pdf")) {
+            File probeFile = probe.getFile();
            for (int pageIndex = 0; pageIndex < totalPages; pageIndex++) {
-                PDPage page = sourceDocument.getPage(pageIndex);
-                scratch.addPage(new PDPage(page.getCOSObject()));
-                currentRange.add(pageIndex);
-
-                int pageAdded = currentRange.size();
+                rangeEnd = pageIndex;
+                int pageAdded = rangeEnd - rangeStart + 1;
                boolean shouldCheckSize =
                        (pageAdded % baseCheckFrequency == 0)
                                || (pageIndex == totalPages - 1)
@@ -185,117 +206,110 @@ public class SplitPdfBySizeController {
                if (!shouldCheckSize) {
                    continue;
                }
-
-                long actualSize;
-                try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
-                    scratch.save(out);
-                    actualSize = out.size();
-                }
+                long actualSize = saveRange(sourceDoc, rangeStart, rangeEnd, probeFile);

                if (actualSize > maxBytes) {
-                    if (scratch.getNumberOfPages() > 1) {
-                        scratch.removePage(scratch.getNumberOfPages() - 1);
-                        currentRange.remove(currentRange.size() - 1);
-                        pageIndex--; // retry this page in the next chunk
+                    if (pageAdded > 1) {
+                        rangeEnd = pageIndex - 1;
+                        pageIndex--;
                    }
-                    ranges.add(new ArrayList<>(currentRange));
-                    currentRange.clear();
-                    scratch.close();
-                    scratch = new PDDocument();
+                    ranges.add(buildRange(rangeStart, rangeEnd));
+                    rangeStart = rangeEnd + 1;
+                    rangeEnd = rangeStart - 1;
                } else if (pageIndex < totalPages - 1 && actualSize < maxBytes * 0.75) {
-                    int extraPagesAdded =
-                            lookAheadFit(scratch, sourceDocument, pageIndex, maxBytes);
-                    for (int i = 0; i < extraPagesAdded; i++) {
-                        int extra = pageIndex + 1 + i;
-                        scratch.addPage(new PDPage(sourceDocument.getPage(extra).getCOSObject()));
-                        currentRange.add(extra);
-                    }
-                    pageIndex += extraPagesAdded;
+                    int extra =
+                            lookAheadFit(
+                                    sourceDoc,
+                                    rangeStart,
+                                    pageIndex,
+                                    maxBytes,
+                                    totalPages,
+                                    probeFile);
+                    pageIndex += extra;
+                    rangeEnd = pageIndex;
                }
            }
-
-            if (!currentRange.isEmpty()) {
-                ranges.add(new ArrayList<>(currentRange));
-            }
-        } finally {
-            scratch.close();
+        }
+        if (rangeEnd >= rangeStart) {
+            ranges.add(buildRange(rangeStart, rangeEnd));
        }
        return ranges;
    }

-    /** Speculatively tries up to 5 next pages; returns how many fit under {@code maxBytes}. */
-    private int lookAheadFit(PDDocument scratch, PDDocument source, int pageIndex, long maxBytes)
+    private long saveRange(PdfDocument sourceDoc, int from, int to, File output)
            throws IOException {
-        int totalPages = source.getNumberOfPages();
-        int pagesToLookAhead = Math.min(5, totalPages - pageIndex - 1);
-        if (pagesToLookAhead == 0) {
-            return 0;
+        try (PdfDocument split = PdfSplit.extractPageRange(sourceDoc, from, to)) {
+            split.save(output.toPath());
        }
-
-        int extraPagesAdded = 0;
-        try (PDDocument testDoc = new PDDocument()) {
-            for (int i = 0; i < scratch.getNumberOfPages(); i++) {
-                testDoc.addPage(new PDPage(scratch.getPage(i).getCOSObject()));
-            }
-            for (int i = 0; i < pagesToLookAhead; i++) {
-                testDoc.addPage(new PDPage(source.getPage(pageIndex + 1 + i).getCOSObject()));
-                long testSize;
-                try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
-                    testDoc.save(out);
-                    testSize = out.size();
-                }
-                if (testSize > maxBytes) {
-                    break;
-                }
-                extraPagesAdded++;
-            }
-        }
-        return extraPagesAdded;
+        return output.length();
    }

-    private List<List<Integer>> computePageCountRanges(PDDocument sourceDocument, int pageCount) {
+    private int lookAheadFit(
+            PdfDocument sourceDoc,
+            int rangeStart,
+            int currentEnd,
+            long maxBytes,
+            int totalPages,
+            File probeFile)
+            throws IOException {
+        int pagesToLookAhead = Math.min(5, totalPages - currentEnd - 1);
+        int extra = 0;
+        for (int i = 0; i < pagesToLookAhead; i++) {
+            int trialEnd = currentEnd + 1 + i;
+            long size = saveRange(sourceDoc, rangeStart, trialEnd, probeFile);
+            if (size > maxBytes) {
+                break;
+            }
+            extra++;
+        }
+        return extra;
+    }
+
+    private List<int[]> computePageCountRanges(PdfDocument sourceDoc, int pageCount) {
        if (pageCount <= 0) {
            throw ExceptionUtils.createIllegalArgumentException(
                    "error.invalidArgument", "Invalid argument: {0}", "page count: " + pageCount);
        }
-        int totalPages = sourceDocument.getNumberOfPages();
-        List<List<Integer>> ranges = new ArrayList<>();
-        List<Integer> current = new ArrayList<>(pageCount);
-        for (int i = 0; i < totalPages; i++) {
-            current.add(i);
-            if (current.size() == pageCount) {
-                ranges.add(current);
-                current = new ArrayList<>(pageCount);
-            }
-        }
-        if (!current.isEmpty()) {
-            ranges.add(current);
+        int totalPages = sourceDoc.pageCount();
+        List<int[]> ranges = new ArrayList<>();
+        int start = 0;
+        while (start < totalPages) {
+            int end = Math.min(start + pageCount - 1, totalPages - 1);
+            ranges.add(buildRange(start, end));
+            start = end + 1;
        }
        return ranges;
    }

-    private List<List<Integer>> computeDocCountRanges(
-            PDDocument sourceDocument, int documentCount) {
+    private List<int[]> computeDocCountRanges(PdfDocument sourceDoc, int documentCount) {
        if (documentCount <= 0) {
            throw ExceptionUtils.createIllegalArgumentException(
                    "error.invalidArgument",
                    "Invalid argument: {0}",
                    "document count: " + documentCount);
        }
-        int totalPages = sourceDocument.getNumberOfPages();
+        int totalPages = sourceDoc.pageCount();
        int pagesPerDocument = totalPages / documentCount;
        int extraPages = totalPages % documentCount;
-
-        List<List<Integer>> ranges = new ArrayList<>();
+        List<int[]> ranges = new ArrayList<>();
        int cursor = 0;
        for (int i = 0; i < documentCount; i++) {
            int pagesToAdd = pagesPerDocument + (i < extraPages ? 1 : 0);
-            List<Integer> range = new ArrayList<>(pagesToAdd);
-            for (int j = 0; j < pagesToAdd; j++) {
-                range.add(cursor++);
+            if (pagesToAdd == 0) {
+                continue;
            }
-            ranges.add(range);
+            int end = cursor + pagesToAdd - 1;
+            ranges.add(buildRange(cursor, end));
+            cursor = end + 1;
        }
        return ranges;
    }
+
+    private static int[] buildRange(int start, int end) {
+        int[] range = new int[end - start + 1];
+        for (int i = 0; i < range.length; i++) {
+            range[i] = start + i;
+        }
+        return range;
+    }
 }