The sample of pdfbox. How to convert pdf to images and how to set protect password using Java pdfbox.

PDFOperator.java

package com.test;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Date;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.encryption.AccessPermission;
import org.apache.pdfbox.pdmodel.encryption.StandardProtectionPolicy;
import org.apache.pdfbox.rendering.ImageType;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.apache.pdfbox.tools.imageio.ImageIOUtil;
import org.apache.pdfbox.pdmodel.PDDocumentInformation;

public class PDFOperator {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		try {
			PDDocument doc = PDDocument.load(new File("/home/user/test.pdf"));

			copyPDFWithKey(doc, "123", "456", "/home/user/protected-test.pdf");
			System.out.println(new Date().toString());
			pdf2Images(doc, "/home/user/images/");
			System.out.println(new Date().toString());
			doc.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}
	
	private static void pdf2Images(PDDocument doc, String outputDir) throws IOException {
		PDFRenderer pdfRenderer = new PDFRenderer(doc);
		int pageCounter = 0;
		PDDocumentInformation df = doc.getDocumentInformation();
		for (PDPage page : doc.getPages())
		{
		    // note that the page number parameter is zero based
		    BufferedImage bim = pdfRenderer.renderImageWithDPI(pageCounter, 300, ImageType.RGB);

		    // suffix in filename will be used as the file format
		    ImageIOUtil.writeImage(bim, outputDir + "/test-" + (pageCounter++) + ".png", 300);
		}
	}
	
	private static void copyPDFWithKey(PDDocument doc, String ownerPassword, String readerPassword, String outputDir) throws IOException {
		int keyLength = 128;
		AccessPermission ap = new AccessPermission();
		ap.setReadOnly();
		
		StandardProtectionPolicy spp = new StandardProtectionPolicy(ownerPassword, readerPassword, ap);
		spp.setEncryptionKeyLength(keyLength);
		spp.setPermissions(ap);
		doc.protect(spp);
		doc.save(outputDir);
	}

}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>PDFOperator</groupId>
  <artifactId>PDFOperator</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <dependencies>
	<dependency>
	  <groupId>org.apache.pdfbox</groupId>
	  <artifactId>pdfbox</artifactId>
	  <version>2.0.4</version>
	</dependency>
	<dependency>
	  <groupId>org.bouncycastle</groupId>
	  <artifactId>bcprov-jdk15on</artifactId>
	  <version>1.56</version>
	</dependency>
	<dependency>
      <groupId>org.apache.pdfbox</groupId>
	  <artifactId>pdfbox-tools</artifactId>
	  <version>2.0.4</version>
	</dependency>
  </dependencies>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.5.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>