Add batch utility classes which uses Java 21 virtual threads.

Author: andreasrosdal

openpdf-core/src/main/java/org/openpdf/text/pdf/PdfBatchUtils.java

@@ -0,0 +1,296 @@
+/*
+ * Copyright 2025 OpenPDF
+ *
+ * The contents of this file are subject to the Mozilla Public License Version 1.1
+ * (the "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the License.
+ *
+ * The Original Code is 'iText, a free JAVA-PDF library'.
+ *
+ * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
+ * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
+ * All Rights Reserved.
+ * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
+ * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
+ *
+ * Contributor(s): all the names of the contributors are added in the source code
+ * where applicable.
+ *
+ * Alternatively, the contents of this file may be used under the terms of the
+ * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
+ * provisions of LGPL are applicable instead of those above.  If you wish to
+ * allow use of your version of this file only under the terms of the LGPL
+ * License and not to allow others to use your version of this file under
+ * the MPL, indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by the LGPL.
+ * If you do not delete the provisions above, a recipient may use your version
+ * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the MPL as stated above or under the terms of the GNU
+ * Library General Public License as published by the Free Software Foundation;
+ * either version 2 of the License, or any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
+ * details.
+ *
+ * If you didn't download this code from the following link, you should check if
+ * you aren't using an obsolete version:
+ * https://github.com/LibrePDF/OpenPDF
+ */
+
+package org.openpdf.text.pdf;
+
+import org.openpdf.text.Document;
+import org.openpdf.text.DocumentException;
+import org.openpdf.text.Element;
+import org.openpdf.text.Font;
+import org.openpdf.text.Rectangle;
+
+import java.io.Closeable;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Objects;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.function.Consumer;
+
+/**
+ * PDF batch utilities using Java 21 virtual threads.
+ *
+ */
+public final class PdfBatchUtils {
+
+    private PdfBatchUtils() {}
+
+    /** Generic result container for batch operations. */
+    public static final class BatchResult<T> {
+        public final List<T> successes = new ArrayList<>();
+        public final List<Throwable> failures = new ArrayList<>();
+        public boolean isAllSuccessful() { return failures.isEmpty(); }
+        public int total() { return successes.size() + failures.size(); }
+        @Override public String toString() {
+            return "BatchResult{" +
+                    "successes=" + successes.size() +
+                    ", failures=" + failures.size() +
+                    ", total=" + total() +
+                    '}';
+        }
+    }
+
+    // ------------------------- Common job records -------------------------
+
+    /** Merge several PDFs into one. */
+    public record MergeJob(List<Path> inputs, Path output) {}
+
+    /** Add a semi-transparent text watermark to all pages. */
+    public record WatermarkJob(Path input, Path output, String text, float fontSize, float opacity) {}
+
+    /** Encrypt a PDF with given passwords and permissions. */
+    public record EncryptJob(Path input, Path output,
+                             String userPassword, String ownerPassword,
+                             int permissions, int encryptionType) {}
+
+    /** Split one PDF into per-page PDFs in the given directory (files will be named baseName_pageX.pdf). */
+    public record SplitJob(Path input, Path outputDir, String baseName) {}
+
+    // ------------------------- Public batch APIs -------------------------
+
+    /** Run arbitrary tasks on virtual threads with optional progress callback. */
+    public static <T> BatchResult<T> runBatch(Collection<? extends Callable<T>> tasks,
+            Consumer<T> onSuccess,
+            Consumer<Throwable> onFailure) {
+        Objects.requireNonNull(tasks, "tasks");
+        var result = new BatchResult<T>();
+        if (tasks.isEmpty()) return result;
+
+        try (ExecutorService exec = Executors.newVirtualThreadPerTaskExecutor()) {
+            List<Future<T>> futures = tasks.stream().map(exec::submit).toList();
+            for (Future<T> f : futures) {
+                try {
+                    T v = f.get();
+                    result.successes.add(v);
+                    if (onSuccess != null) onSuccess.accept(v);
+                } catch (ExecutionException ee) {
+                    Throwable cause = ee.getCause() != null ? ee.getCause() : ee;
+                    result.failures.add(cause);
+                    if (onFailure != null) onFailure.accept(cause);
+                } catch (InterruptedException ie) {
+                    Thread.currentThread().interrupt();
+                    result.failures.add(ie);
+                    if (onFailure != null) onFailure.accept(ie);
+                }
+            }
+        }
+        return result;
+    }
+
+    // ------------------------- Merge -------------------------
+
+    /** Merge one set of inputs into a single output file. */
+    public static Path merge(List<Path> inputs, Path output) throws IOException, DocumentException {
+        Objects.requireNonNull(inputs, "inputs");
+        Objects.requireNonNull(output, "output");
+        Files.createDirectories(output.getParent());
+
+        try (var fos = new FileOutputStream(output.toFile())) {
+            Document doc = new Document();
+            PdfCopy copy = new PdfCopy(doc, fos);
+            doc.open();
+            for (Path in : inputs) {
+                try (PdfReader reader = new PdfReader(Files.readAllBytes(in))) {
+                    int n = reader.getNumberOfPages();
+                    for (int i = 1; i <= n; i++) {
+                        copy.addPage(copy.getImportedPage(reader, i));
+                    }
+                }
+            }
+            doc.close();
+        }
+        return output;
+    }
+
+    /** Batch merge. */
+    public static BatchResult<Path> batchMerge(List<MergeJob> jobs, Consumer<Path> onSuccess, Consumer<Throwable> onFailure) {
+        return runBatch(jobs.stream().map(job -> (Callable<Path>) () -> merge(job.inputs, job.output)).toList(), onSuccess, onFailure);
+    }
+
+    // ------------------------- Watermark -------------------------
+
+    /** Watermark one PDF with text on every page (centered, diagonal). */
+    public static Path watermark(Path input, Path output, String text, float fontSize, float opacity)
+            throws IOException, DocumentException {
+        Files.createDirectories(output.getParent());
+        try (PdfReader reader = new PdfReader(Files.readAllBytes(input));
+                var out = new FileOutputStream(output.toFile())) {
+            PdfStamper stamper = new PdfStamper(reader, out);
+            BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA, BaseFont.WINANSI, BaseFont.EMBEDDED);
+            Font font = new Font(bf, fontSize);
+
+            PdfGState gs = new PdfGState();
+            gs.setFillOpacity(opacity);
+
+            int n = reader.getNumberOfPages();
+            for (int i = 1; i <= n; i++) {
+                Rectangle pageSize = reader.getPageSizeWithRotation(i);
+                float x = (pageSize.getLeft() + pageSize.getRight()) / 2f;
+                float y = (pageSize.getTop() + pageSize.getBottom()) / 2f;
+
+                PdfContentByte over = stamper.getOverContent(i);
+                over.saveState();
+                over.setGState(gs);
+                over.beginText();
+                over.setFontAndSize(bf, font.getSize());
+                over.showTextAligned(Element.ALIGN_CENTER, text, x, y, 45f);
+                over.endText();
+                over.restoreState();
+            }
+            stamper.close();
+        }
+        return output;
+    }
+
+    /** Batch watermark. */
+    public static BatchResult<Path> batchWatermark(List<WatermarkJob> jobs, Consumer<Path> onSuccess, Consumer<Throwable> onFailure) {
+        return runBatch(jobs.stream().map(j -> (Callable<Path>) () -> watermark(j.input, j.output, j.text, j.fontSize, j.opacity)).toList(), onSuccess, onFailure);
+    }
+
+    // ------------------------- Encrypt -------------------------
+
+    /** Encrypt one PDF. */
+    public static Path encrypt(Path input, Path output,
+            String userPassword, String ownerPassword,
+            int permissions, int encryptionType)
+            throws IOException, DocumentException {
+        Files.createDirectories(output.getParent());
+        try (PdfReader reader = new PdfReader(Files.readAllBytes(input));
+                var out = new FileOutputStream(output.toFile())) {
+            PdfStamper stamper = new PdfStamper(reader, out);
+            stamper.setEncryption(
+                    userPassword != null ? userPassword.getBytes() : null,
+                    ownerPassword != null ? ownerPassword.getBytes() : null,
+                    permissions,
+                    encryptionType);
+            stamper.close();
+        }
+        return output;
+    }
+
+    /** Batch encrypt. */
+    public static BatchResult<Path> batchEncrypt(List<EncryptJob> jobs, Consumer<Path> onSuccess, Consumer<Throwable> onFailure) {
+        return runBatch(jobs.stream().map(j -> (Callable<Path>) () -> encrypt(j.input, j.output, j.userPassword, j.ownerPassword, j.permissions, j.encryptionType)).toList(), onSuccess, onFailure);
+    }
+
+    // ------------------------- Split -------------------------
+
+    /** Split one PDF to per-page PDFs. */
+    public static List<Path> split(Path input, Path outputDir, String baseName) throws IOException, DocumentException {
+        Files.createDirectories(outputDir);
+        List<Path> outputs = new ArrayList<>();
+        try (PdfReader reader = new PdfReader(Files.readAllBytes(input))) {
+            int n = reader.getNumberOfPages();
+            for (int i = 1; i <= n; i++) {
+                Path out = outputDir.resolve(baseName + "_page" + i + ".pdf");
+                try (var fos = new FileOutputStream(out.toFile())) {
+                    Document doc = new Document(reader.getPageSizeWithRotation(i));
+                    PdfCopy copy = new PdfCopy(doc, fos);
+                    doc.open();
+                    copy.addPage(copy.getImportedPage(reader, i));
+                    doc.close();
+                }
+                outputs.add(out);
+            }
+        }
+        return outputs;
+    }
+
+    /** Batch split. */
+    public static BatchResult<List<Path>> batchSplit(List<SplitJob> jobs, Consumer<List<Path>> onSuccess, Consumer<Throwable> onFailure) {
+        return runBatch(jobs.stream().map(j -> (Callable<List<Path>>) () -> split(j.input, j.outputDir, j.baseName)).toList(), onSuccess, onFailure);
+    }
+
+    // ------------------------- Convenience helpers -------------------------
+
+    /** Quick permissions helper. */
+    public static int perms(boolean print, boolean modify, boolean copy, boolean annotate) {
+        int p = 0;
+        if (print) p |= PdfWriter.ALLOW_PRINTING;
+        if (modify) p |= PdfWriter.ALLOW_MODIFY_CONTENTS;
+        if (copy) p |= PdfWriter.ALLOW_COPY;
+        if (annotate) p |= PdfWriter.ALLOW_MODIFY_ANNOTATIONS;
+        return p;
+    }
+
+    /** AES 128 vs 256 convenience. */
+    public static int aes128() { return PdfWriter.ENCRYPTION_AES_128; }
+    public static int aes256() { return PdfWriter.ENCRYPTION_AES_256_V3; }
+
+    /** Small utility for closing Closeables, ignoring exceptions. */
+    private static void closeQuietly(Closeable c) { try { if (c != null) c.close(); } catch (Exception ignored) {} }
+
+    /** Simple example that shows how to use batch APIs. Remove in production. */
+    public static void main(String[] args) throws Exception {
+        // Example: watermark a bunch of PDFs using virtual threads
+        List<WatermarkJob> jobs = List.of(
+                new WatermarkJob(Path.of("in1.pdf"), Path.of("out1.pdf"), "CONFIDENTIAL", 72f, 0.12f),
+                new WatermarkJob(Path.of("in2.pdf"), Path.of("out2.pdf"), "DRAFT "+ Instant.now(), 64f, 0.10f)
+        );
+        var res = batchWatermark(jobs, p -> System.out.println("OK: " + p), e -> e.printStackTrace());
+        System.out.println(res);
+    }
+}