Merge PDF Documents in Java

In order to better manage and store documents, it is inevitable to combine multiple PDF documents into one document. Here I’ll introduce two ways to merge PDF documents using Free Spire.PDF for Java.

Before beginning, you need to download the required tool Free Spire.PDF for Java from the link, unzip it and import Spire.Pdf.jar located in the “lib” folder into your IDEA. Of course, if you use maven, you need to add the following code to your project’s pom.xml file.

<repositories> 

        <repository> 

            <id>com.e-iceblue</id> 

            <name>e-iceblue</name> 

            <url>http://repo.e-iceblue.com/nexus/content/groups/public/</url> 

        </repository> 

</repositories> 

<dependencies> 

    <dependency> 

        <groupId>e-iceblue</groupId> 

        <artifactId>spire.pdf.free</artifactId> 

        <version>2.6.3</version> 

    </dependency> 

</dependencies> 

Using the code

Method 1

Load three PDF documents and select the first PdfDocument for the purpose of merging the second and third PDF file to it.

import com.spire.pdf.PdfDocument;

public class MergePDF1 {
    public static void main(String[] args) {
        //Load PDF files
        String[] files = new String[]
                {
                        "C:\\Users\\Test1\\Desktop\\Sample01.pdf",
                        "C:\\Users\\Test1\\Desktop\\Sample02.pdf",
                        "C:\\Users\\Test1\\Desktop\\Sample03.pdf",
                };

        //Open pdf documents
        PdfDocument[] docs = new PdfDocument[files.length];
        PdfDocument doc = new PdfDocument();
        for (int i = 0; i < files.length; i++) {
            docs[i] = new PdfDocument();
            docs[i].loadFromFile(files[i]);
        }
        //Append document
        docs[0].appendPage(docs[1]);

        //import pages
        for (int i = 0; i < docs[2].getPages().getCount(); i = i + 2) {
            docs[0].insertPage(docs[2], i);
        }

        // Save pdf file.
        docs[0].saveToFile("output/MergeDocument.pdf");
        doc.close();
    }
}

Method 2

Input the three PDF documents by stream and then use mergeFiles(streams)methods to merge the PDF documents into one PDF document.

import com.spire.pdf.*;

import java.io.*;


public class MergePDF2 {

    public static void main(String[] args) throws FileNotFoundException {

        //Load PDF files

        FileInputStream stream1 = new FileInputStream(new File("C:\\Users\\Test1\\Desktop\\Sample01.pdf"));

        FileInputStream stream2 = new FileInputStream(new File("C:\\Users\\Test1\\Desktop\\Sample02.pdf"));

        FileInputStream stream3 = new FileInputStream(new File("C:\\Users\\Test1\\Desktop\\Sample03.pdf"));

     

               //Input PDF files by stream

        InputStream[] streams = new FileInputStream[]{stream1, stream2, stream3};


        //Merge files by stream

        PdfDocumentBase doc = PdfDocument.mergeFiles(streams);


        //Save the file

        doc.save("output/mergeFilesByStream.pdf");

        doc.close();

    }

}

Output