使用itextpdf将图片转pdf

依赖

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itextpdf</artifactId>
    <version>5.5.10</version>
</dependency>

实现代码

/**
 * 将图片转换为PDF文件
 * @param imageFile 图片文件
 */
public static File generatePdfFile(File imageFile) throws Exception {
    String fileName = imageFile.getName();
    String pdfFileName = fileName.substring(0, fileName.lastIndexOf(".")) + ".pdf";
    //纸张大小A4
//        Document doc = new Document(PageSize.A4, 0, 0, 0, 0);
    //纸张大小7寸，100 × 150 毫米（纵向）
    float mm100Width = mmToPoints(100);
    float mm150Height = mmToPoints(150);
    RectangleReadOnly rectangleReadOnly = new RectangleReadOnly(mm100Width, mm150Height);
    Document doc = new Document(rectangleReadOnly, 0, 0, 0, 0);
    PdfWriter.getInstance(doc, Files.newOutputStream(Paths.get(pdfFileName)));
    doc.open();
    doc.newPage();
    Image image = Image.getInstance(Files.readAllBytes(imageFile.toPath()));
    float height = image.getHeight();
    float width = image.getWidth();
    int percent = getPercent(rectangleReadOnly, height, width);
    image.setAlignment(Image.MIDDLE);
    image.scalePercent(percent);
    doc.add(image);
    doc.close();
    return new File(pdfFileName);
}

/**
 * 等比压缩，获取压缩百分比
 *
 * @param height 图片的高度
 * @param weight 图片的宽度
 * @return 压缩百分比
 */
private static int getPercent(RectangleReadOnly rectangleReadOnly, float height, float weight) {
    float percent = 0.0F;
    if (height > weight) {
        percent = rectangleReadOnly.getHeight() / height * 100;
    } else {
        percent = rectangleReadOnly.getWidth() / weight * 100;
    }
    return Math.round(percent);
}


/**
 * 将毫米转换为点
 * @param mm 尺寸大小，单位毫米 (1 mm = 2.83465 points)
 */
private static float mmToPoints(float mm) {
    return mm * 2.83465f;
}