我遇到过许多使用PDFBox Layer Utility的appendFormAsLayer方法的示例，如下所示：
/**
* Places the given form over the existing content of the indicated page (like an overlay).
* The form is enveloped in a marked content section to indicate that it's part of an
* optional content group (OCG), here used as a layer. This optional group is returned and
* can be enabled and disabled through methods on {@link PDOptionalContentProperties}.
* @param targetPage the target page
* @param form the form to place
* @param transform the transformation matrix that controls the placement
* @param layerName the name for the layer/OCG to produce
* @return the optional content group that was generated for the form usage
* @throws IOException if an I/O error occurs
*/
public PDOptionalContentGroup appendFormAsLayer(PDPage targetPage,
PDXObjectForm form, AffineTransform transform,
String layerName) throws IOException
{
PDDocumentCatalog catalog = targetDoc.getDocumentCatalog();
PDOptionalContentProperties ocprops = catalog.getOCProperties();
if (ocprops == null)
{
ocprops = new PDOptionalContentProperties();
catalog.setOCProperties(ocprops);
}
if (ocprops.hasGroup(layerName))
{
throw new IllegalArgumentException("Optional group (layer) already exists: " + layerName);
}
PDOptionalContentGroup layer = new PDOptionalContentGroup(layerName);
ocprops.addGroup(layer);
PDResources resources = targetPage.findResources();
PDPropertyList props = resources.getProperties();
if (props == null)
{
props = new PDPropertyList();
resources.setProperties(props);
}
//Find first free resource name with the pattern "MC<index>"
int index = 0;
PDOptionalContentGroup ocg;
COSName resourceName;
do
{
resourceName = COSName.getPDFName("MC" + index);
ocg = props.getOptionalContentGroup(resourceName);
index++;
} while (ocg != null);
//Put mapping for our new layer/OCG
props.putMapping(resourceName, layer);
PDPageContentStream contentStream = new PDPageContentStream(
targetDoc, targetPage, true, !DEBUG);
contentStream.beginMarkedContentSequence(COSName.OC, resourceName);
contentStream.drawXObject(form, transform);
contentStream.endMarkedContentSequence();
contentStream.close();
return layer;
}
前一段代码中getPDFName调用中“MC”的意义是什么？
我编写了以下代码，在现有pdf的每个页面上插入水印，并启用每组可选内容。
LayerUtility layerUtility = new LayerUtility(document);
PDXObjectForm form = layerUtility.importPageAsForm(overlayDoc, 0);
for (int i = 0; i < document.getDocumentCatalog().getAllPages().size(); i++) {
PDPage page = (PDPage) document.getDocumentCatalog().getAllPages().get(i);
PDOptionalContentGroup ocGroup = layerUtility.appendFormAsLayer(page, form, new AffineTransform(), "watermark" + i);
}
PDOptionalContentProperties ocprops = document.getDocumentCatalog().getOCProperties();
for (String groupName : ocprops.getGroupNames()) {
if (groupName.startsWith("watermark")) {
ocprops.setGroupEnabled(groupName, true);
}
}
将组设置为启用或禁用“setGroupEnabled（groupName，true）”会使其显示和打印。根据我在这个主题上研究的其他信息，当可选内容可见时，可以更精细地调整，这表明存在onScreen和onPrint布尔属性，可以设置这些属性来确定内容的可见性。见https://acrobatusers.com/tutorials/watermarking-a-pdf-with-javascript
是否有办法使用PDFBox在打印时显示水印，但在显示时不显示？如果没有，任何替代解决方案的建议都将受到赞赏。
以下是从字符串（createOverlay）创建水印pdf的附加代码和调用LayerUtility传递水印文档的函数（addWatermark）。所需的只是从任何现有的pdf文件创建PDDocument并使用水印字符串传递它。
public PDDocument addWatermark(PDDocument document, String text) throws IOException {
PDDocument overlayDoc = createOverlay(text);
// Create the watermark in an optional content group
LayerUtility layerUtility = new LayerUtility(document);
PDXObjectForm form = layerUtility.importPageAsForm(overlayDoc, 0);
for (int i = 0; i < document.getDocumentCatalog().getAllPages().size(); i++) {
PDPage page = (PDPage) document.getDocumentCatalog().getAllPages().get(i);
layerUtility.appendFormAsLayer(page, form, new AffineTransform(), "watermark" + i);
}
return document;
}
private PDDocument createOverlay(String text) throws IOException {
// Create a document and add a page to it
PDDocument document = new PDDocument();
PDPage page = new PDPage();
document.addPage(page);
PDExtendedGraphicsState extendedGraphicsState = new PDExtendedGraphicsState();
// Set the transparency/opacity
extendedGraphicsState.setNonStrokingAlphaConstant(0.4f);
if (page.findResources() == null) {
page.setResources(new PDResources());
}
PDResources resources = page.findResources();// Get the page resources.
// Get the defined graphic states.
if (resources.getGraphicsStates() == null)
{
resources.setGraphicsStates(new HashMap<String, PDExtendedGraphicsState>());
}
Map<String, PDExtendedGraphicsState> graphicsStateDictionary = resources.getGraphicsStates();
if (graphicsStateDictionary != null){
graphicsStateDictionary.put("TransparentState", extendedGraphicsState);
resources.setGraphicsStates(graphicsStateDictionary);
}
// the x/y coords
Float xVal = 0f; //Float.parseFloat(config.getProperty("ss.xVal"));
Float yVal = 0f; //Float.parseFloat(config.getProperty("ss.yVal"));
// Start a new content stream which will "hold" the to be created content
PDPageContentStream contentStream = new PDPageContentStream(document, page, true, true);
contentStream.appendRawCommands("/TransparentState gs\n");
// Create the text and position it
contentStream.beginText();
contentStream.setFont(font, fontSize);
contentStream.setTextRotation(Math.PI/4,page.getMediaBox().getWidth()/4,page.getMediaBox().getHeight()/4);
contentStream.setNonStrokingColor(210,210,210); //light grey
contentStream.moveTextPositionByAmount(xVal, yVal);
contentStream.drawString(text);
contentStream.endText();
// Make sure that the content stream is closed:
contentStream.close();
//return the string doc
return document;
}
答案 0 :(得分：1)
private void addWaterMark(PDDocument document) throws Exception
{
PDDocumentCatalog catalog = document.getDocumentCatalog();
PDOptionalContentProperties ocprops = catalog.getOCProperties();
if (ocprops == null)
{
ocprops = new PDOptionalContentProperties();
ocprops.setBaseState(BaseState.OFF);
catalog.setOCProperties(ocprops);
}
String layerName = "conWatermark";
PDOptionalContentGroup watermark = null;
if (ocprops.hasGroup(layerName))
{
watermark = ocprops.getGroup(layerName);
}
else
{
watermark = new PDOptionalContentGroup(layerName);
ocprops.addGroup(watermark);
}
COSDictionary watermarkDic = watermark.getCOSObject();
COSDictionary printState = new COSDictionary();
printState.setItem("PrintState", COSName.ON);
COSDictionary print = new COSDictionary();
print.setItem("Print", printState);
watermarkDic.setItem("Usage", print);
COSDictionary asPrint = new COSDictionary();
asPrint.setItem("Event", COSName.getPDFName("Print"));
COSArray category = new COSArray();
category.add(COSName.getPDFName("Print"));
asPrint.setItem("Category", category);
COSArray ocgs = new COSArray();
ocgs.add(watermarkDic);
asPrint.setItem(COSName.OCGS, ocgs);
COSArray as = new COSArray();
as.add(asPrint);
COSDictionary d = (COSDictionary) ((COSDictionary) ocprops.getCOSObject()).getDictionaryObject(COSName.D);
d.setItem(COSName.AS, as);
for (int n = 0; n < document.getNumberOfPages(); n++)
{
PDPage page = document.getPage(n);
PDResources resources = page.getResources();
if (resources == null)
{
resources = new PDResources();
page.setResources(resources);
}
String text1 = "Confidential";
String text2 = "Document ..."; //
PDExtendedGraphicsState graphicsState = new PDExtendedGraphicsState();
graphicsState.setNonStrokingAlphaConstant(0.08f);
PDPageContentStream contentStream = new PDPageContentStream(document, page, AppendMode.APPEND, true, true);
contentStream.setGraphicsStateParameters(graphicsState);
contentStream.setNonStrokingColor(Color.GRAY);
contentStream.beginMarkedContent(COSName.OC, watermark);
contentStream.beginText();
PDRectangle pageSize = page.getBBox();
float fontSize = this.getFittingFontSize(pageSize, text1);
PDFont font = this.WATERMARK_FONT;
contentStream.setFont(font, fontSize);
float text1Width = this.getTextWidth(font, fontSize, text1);
float rotation = (float) Math.atan(pageSize.getHeight() / pageSize.getWidth());
Point p = this.getStartPoint(pageSize, fontSize, text1);
AffineTransform at = new AffineTransform(1, 0, 0, 1, p.getX(), p.getY());
at.rotate(rotation);
Matrix matrix = new Matrix(at);
contentStream.setTextMatrix(matrix);
contentStream.showText(text1);
fontSize = this.getFittingFontSize(pageSize, text2);
contentStream.setFont(font, fontSize);
contentStream.newLineAtOffset(-(this.getTextWidth(font, fontSize, text2) - text1Width) / 2, -fontSize * 1.2f);
contentStream.showText(text2);
contentStream.endMarkedContent();
contentStream.endText();
contentStream.close();
}
}