To make a PDF Stamper, you will need the following prerequisites:

1. Java IDE

You can use any Java-supported IDE. There are a bunch of IDEs available for Java development. This demonstration will be using IntelliJ IDE. You can use NetBeans, Eclipse, etc.

2. Maven Project

Maven is a dependency manager and allows control over the Java project. Maven for Java can be downloaded from the official Maven website. IntelliJ IDE for Java contains Maven support.

3. IronPDF

You can download and install IronPDF for Java in multiple ways.

• Adding IronPDF dependency in the pom.xml file in the Maven project.

<dependency>
    <groupId>com.ironsoftware</groupId>
    <artifactId>ironpdf</artifactId>
    <version>LATEST_VERSION</version> 
</dependency>

<dependency>
    <groupId>com.ironsoftware</groupId>
    <artifactId>ironpdf</artifactId>
    <version>LATEST_VERSION</version> 
</dependency>

• Visit the Maven website and download the latest IronPDF package for Java from the Maven repository for IronPDF.
• Directly download IronPDF from the IronPDF official download section on IronPDF.com.
• Manually install IronPDF using the IronPDF JAR file in your Java application.

4. Slf4j

This dependency is also required to stamp content on an existing PDF document. It can be added using the Maven dependencies manager in IntelliJ or directly downloaded from the Maven website. Add the following dependency to the pom.xml file:

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>2.0.5</version>
</dependency>

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>2.0.5</version>
</dependency>

IronPDF provides a stamp package. It allows a bunch of useful stamping options like BarcodeStamper, HtmlStamper, ImageStamper, TextStamper, and others for content alignment. To add new HTML content to this PDF document HtmlStamper class will be used. Let's use the file in the previous section and add some content to it. The following code helps to achieve this task:

// Create an HtmlStamper and set its content
HtmlStamper htmlStamper = new HtmlStamper();
htmlStamper.setHtml("New content added!");

// Create an HtmlStamper and set its content
HtmlStamper htmlStamper = new HtmlStamper();
htmlStamper.setHtml("New content added!");

A HtmlStamper object is created and then used its setHtml method to attach new HTML code. The next step is to apply it to the existing PDF document to create a new PDF version.

Adding all the Interactive Elements to PDF Document

Using the PdfDocument object created earlier to add the HTML code to the existing document. It provides applyStamp with two overloads, one that accepts only the content as a Stamper object and the other with page selection as well.

// Apply the stamper to the PDF document
pd.applyStamp(htmlStamper);

// Apply the stamper to the PDF document
pd.applyStamp(htmlStamper);

This will add the string description to the existing document.

Saving the Changes to the PDF

To save the file, use the saveAs method of the PdfDocument object.

// Save the modified PDF document
pd.saveAs("stamped.pdf");

// Save the modified PDF document
pd.saveAs("stamped.pdf");

The stamped PDF file

The HTML string is added to every page of the PDF document and at the middle of every page.

Stamp to Specific Pages

You can use another overload of the applyStamp method to add the content to a specific page.

// Stamp content to a specific page
pd.applyStamp(htmlStamper, PageSelection.singlePage(1));

// Stamp content to a specific page
pd.applyStamp(htmlStamper, PageSelection.singlePage(1));

PageSelection class provides different methods to control the page number. firstPage, lastPage, allPages, and pageRange are some methods available to add the content appropriately.

Aligning the Content

You can use setVerticalAlignment, setHorizontalAlignment, setWidth, setHeight methods in each Stamper class to adjust the position of the content added to the existing PDF document. The following example code will help to place the text at the bottom left of the page:

// Set the alignment of the stamper
htmlStamper.setHorizontalAlignment(HorizontalAlignment.LEFT);
htmlStamper.setVerticalAlignment(VerticalAlignment.BOTTOM);

// Set the alignment of the stamper
htmlStamper.setHorizontalAlignment(HorizontalAlignment.LEFT);
htmlStamper.setVerticalAlignment(VerticalAlignment.BOTTOM);

The output PDF file with stamper alignment

You can use setVerticalOffset, setHorizontalOffset method to further adjust the positioning of the content.

For more information on working with PDF files using IronPDF visit this code example for HTML to PDF conversion in Java.

IronPDF for Java is a versatile library and provides the facility to add file descriptions in the form of metadata, user permissions, user password, add digital signature, and create signed documents to save the version of the PDF document.

Metadata

// Edit file metadata
MetadataManager metadata = pd.getMetadata();
metadata.setAuthor("Satoshi Nakamoto");
metadata.setKeywords("SEO, Friendly");
metadata.setModifiedDate(new Date().toString());

// Edit file metadata
MetadataManager metadata = pd.getMetadata();
metadata.setAuthor("Satoshi Nakamoto");
metadata.setKeywords("SEO, Friendly");
metadata.setModifiedDate(new Date().toString());

Security Options

You can also control the security options of your PDF file so that data is saved from unauthorized use. It provides options to set setAllowUserPrinting, setAllowUserEdits, setAllowUserCopyPasteContent, setAllowUserAnnotations, setUserPassword, setAllowUserFormData parameters to true or false. The following sample code will help to set all the objects properties mentioned above.

// Edit file security settings
SecurityOptions securityOptions = new SecurityOptions();
securityOptions.setAllowUserCopyPasteContent(false);
securityOptions.setAllowUserAnnotations(false);
securityOptions.setAllowUserPrinting(PdfPrintSecurity.FULL_PRINT_RIGHTS);
securityOptions.setAllowUserFormData(false);
securityOptions.setOwnerPassword("top-secret");
securityOptions.setUserPassword("sharable");

// Edit file security settings
SecurityOptions securityOptions = new SecurityOptions();
securityOptions.setAllowUserCopyPasteContent(false);
securityOptions.setAllowUserAnnotations(false);
securityOptions.setAllowUserPrinting(PdfPrintSecurity.FULL_PRINT_RIGHTS);
securityOptions.setAllowUserFormData(false);
securityOptions.setOwnerPassword("top-secret");
securityOptions.setUserPassword("sharable");

User Password

// Change or set the document encryption password
SecurityManager securityManager = pd.getSecurity();
securityManager.removePasswordsAndEncryption();
securityManager.makePdfDocumentReadOnly("secret-key");

securityManager.setSecurityOptions(securityOptions);
pd.saveAs(Paths.get("assets/secured.pdf"));

// Change or set the document encryption password
SecurityManager securityManager = pd.getSecurity();
securityManager.removePasswordsAndEncryption();
securityManager.makePdfDocumentReadOnly("secret-key");

securityManager.setSecurityOptions(securityOptions);
pd.saveAs(Paths.get("assets/secured.pdf"));

For stamping digital signatures on the actual file, you can see this detailed code example for PDF signatures.