DEV Community: Gia

How to Merge Multiple PDFs into One in Java

Gia — Tue, 31 Oct 2023 09:17:54 +0000

When you need to print multiple PDF files constantly, merging them into one file is a great way to simplify the printing process and save time. In addition, merging PDF files with related content also helps us store and manage documents more easily. Next, I will show you how to merge multiple PDF files into one using a PDF library in Java.

Step 1: Tools

In this tutorial, we will use the following libraries and programs.

IntelliJ IDEA 2018
Free Spire.PDF for Java

This is a totally independent Java PDF library, which doesn’t require Adobe Acrobat or other software installed on system. But this is a free version product and only supports merging PDF files within 10 pages. If you want to merge more pages, you can choose Spire.PDF for Java and apply a 30-days free license.

Step 2: Import JAR file to your project

Download Free Spire.PDF for Java and unzip it.
Create a new project in IntelliJ IDEA and open it.
Click “File”- “Project Structure” - “Modules” - “Dependencies” in turn.
Choose the “JARs or Directories” under the right green plus, and find the “Spire.Pdf.jar” in the lib folder of the downloaded file.

Step 3: Sample Code

import com.spire.pdf.FileFormat;
import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfDocumentBase;

public class test {
    public static void main(String[] args) {

        //Get the paths of the PDFs to be merged
        String[] files = new String[] {
                "C:\\Users\\Administrator\\Desktop\\Sample1.pdf",
                "C:\\Users\\Administrator\\Desktop\\Sample2.pdf",
                "C:\\Users\\Administrator\\Desktop\\Sample3.pdf"};

        //Merge these files
        PdfDocumentBase doc = PdfDocument.mergeFiles(files);

        //Save the result file
        doc.save("C:\\Users\\Administrator\\Desktop\\MergeFiles.pdf", FileFormat.PDF);
    }
}

In this code, we can call PdfDocument.mergeFiles() method to merge pdf files. This method also accepts an array of InputStream as the parameter.

How can I Merge the Selected Page Ranges of PDFs via Python

Gia — Fri, 27 Oct 2023 03:15:03 +0000

Merging PDFs is a great way to avoid constantly opening files when you have multiple related files that need to be processed. You can easily merge them using a PDF editor. However, if you only want to merge specific pages from these PDFs in batches, maybe you can use an excellent PDF library to do that. In this passage, I will show you how to merge specific page ranges of PDFs via Python.

Library

Spire.PDF for Python

Installation

You can install Spire.PDF for Python in Visual Studio Code by performing the following steps:

Download and install Python.
Open Visual Studio Code, click “Extensions”, search for “Python” and then install it.
Click “Explorer” > “NO FOLRDER OPENED” > “Open Folder”.
Choose a folder.
Add a “.py” file to this folder and name it whatever you like.
Click “Terminal” > “New Terminal”.
Last, input the following commands

pip install Spire.PDF

Reference Code

1.Import required modules or libraries.

from spire.pdf import *
from spire.pdf.common import *

2.Created a list containing paths to PDF files.

file1 = "C:/Users/Administrator/Desktop/PDF-1.pdf"
file2 = "C:/Users/Administrator/Desktop/PDF-2.pdf "
file3 = "C:/Users/Administrator/Desktop/PDF-3.pdf "
files = [file1, file2, file3]

3.Then, use the PdfDocument class to load each PDF file as a PdfDocument object and add them to the list.

pdfs = []
for file in files:
    pdfs.append(PdfDocument(file))

4.Create an object of PdfDocument class and insert the selected pages from the loaded PDFs into the new document.

newPdf = PdfDocument()
newPdf.InsertPage(pdfs[0], 0)
newPdf.InsertPage(pdfs[1], 1)
newPdf.InsertPageRange(pdfs[2], 0, 1)

5.Save the new PDF document

newPdf.SaveToFile("output/MergePages.pdf")

Here I take three two-page PDF files as an example and merge their first page, second page and 1-2 pages respectively.

If you want to know more about merging PDFs programmatically, please refer to the following link.
Python: Merge PDF Documents

How to Create a Word Document from Scratch via Python Code

Gia — Fri, 20 Oct 2023 07:49:46 +0000

Creating documentation through a programming language is an automated approach. You can use specialized libraries to do this. Even using code, you can also customize the format and layout of your document to suit your needs. This method can generate documents in batches, thereby improving work efficiency and reducing complicated manual operations. Below are steps to create a simple Word document using Python code.

Tool

Visual Studio Code
Spire.Doc for Python

Installation

You can install Spire.Doc for Python in Visual Studio Code by performing the following steps:

First, make sure that you have download and install Python.
Open VS Code, click “Extensions”, search for “Python” and then install it.
Click “Explorer” > “NO FOLRDER OPENED” > “Open Folder”.
Choose a folder.
Add a “.py” file to this folder and name it whatever you like.
Click “Terminal” > “New Terminal”.
Last, input the following commands

pip install Spire.Doc

Code Example:

This library provides a Document class that is used to represent a model of a Word document. A document must contain at least one section. Each section can contain elements such as paragraphs, tables, charts, and images. Below is a demo of the code. You can modify the code as needed to create the Word document you want.

from spire.doc import * 
from spire.doc.common import *

# Create a Document object
doc = Document()

# Add a section
section = doc.AddSection()

# Set the page margins
section.PageSetup.Margins.All = 40

# Add a title
titleParagraph = section.AddParagraph()
titleParagraph.AppendText("Test")

# Add two paragraphs
bodyParagraph_1 = section.AddParagraph()
bodyParagraph_1.AppendText("This is a test text.")

bodyParagraph_2 = section.AddParagraph()
bodyParagraph_2.AppendText("This is a test text.")

# Apply heading1 to the title
titleParagraph.ApplyStyle(BuiltinStyle.Heading1)

# Create a style for the paragraphs
style2 = ParagraphStyle(doc)
style2.Name = "paraStyle"
style2.CharacterFormat.FontName = "Arial"
style2.CharacterFormat.FontSize = 12
doc.Styles.Add(style2)
bodyParagraph_1.ApplyStyle("paraStyle")
bodyParagraph_2.ApplyStyle("paraStyle")

# Set the horizontal alignment of the paragraphs
titleParagraph.Format.HorizontalAlignment = HorizontalAlignment.Center
bodyParagraph_1.Format.HorizontalAlignment = HorizontalAlignment.Left
bodyParagraph_2.Format.HorizontalAlignment = HorizontalAlignment.Left

# Set the after spacing
titleParagraph.Format.AfterSpacing = 10
bodyParagraph_1.Format.AfterSpacing = 10

# Save to file
doc.SaveToFile("WordDocument.docx", FileFormat.Docx2019)

This Word Python library not only supports processing Word documents easily, but also allows users to convert Word to other formats with high-quality, such as PDF, Text or HTML.

Screenshot

How to Copy a Worksheet in Excel using Python Program

Gia — Wed, 11 Oct 2023 03:13:57 +0000

When you need to create a worksheet that is similar to another one in structure or format, you can directly copy the latter. This method can help you save a significant amount of time by avoiding repetitive work and minimizing input errors. This article will demonstrate how to use Python programs to copy worksheets in Excel files.

Tool

Visual Studio Code
Spire.XLS for Python

This is an Excel library supporting processing Excel document easily on Python platforms, such as creating Excel, reading Excel, converting Excel to image.

Installation

You can install Spire.XLS for Python in Visual Studio Code by performing the following steps:

First, make sure that you have download and install Python.
Open VS Code, click “Extensions”, search for “Python” and then install it.
Click “Explorer” > “NO FOLRDER OPENED” > “Open Folder”.
Choose a desired folder.
Add a “.py” file to this folder and name it whatever you like.
Click “Terminal” > “New Terminal”.
Last, input the following commands

pip install Spire.XLS-for-Python
pip install plum-dispatch==1.7.4

Sample Code

Copy a Worksheet in the Same Workbook

If you need to copy a worksheet in the same workbook, please refer to the following code.In this code, you can add a new worksheet to the workbook with Workbook.Worksheets.Add() method and copy the content from the original sheet to the new one with Worksheet.CopyFrom(Worksheet worksheet) and Workbook.CopyTheme (Workbook srcWorkbook) methods.

from spire.xls import *
from spire.common import *

#Initialize an instance of the Workbook class
workbook = Workbook()
#Load an Excel workbook
workbook.LoadFromFile("Sample 1.xlsx")

#Get the first worksheet
sourceSheet = workbook.Worksheets[0]

sheetName = sourceSheet.Name + "Copy"

#Add a new worksheet with a specific name to the workbook
destSheet = workbook.Worksheets.Add(sheetName)

#Copy the first worksheet to the newly added worksheet
destSheet.CopyFrom(sourceSheet)

#Save the result workbook to another file
workbook.SaveToFile("Result 1.xlsx", ExcelVersion.Version2013)
workbook.Dispose()

Copy a Worksheet to Another Workbook

Likewise, you are also allowed to copy a worksheet from a workbook to another one using the same methods. You just need to create a new workbook and clear the default sheets in it before copying.

from spire.xls import *
from spire.common import *

#Initialize an instance of the Workbook class
sourceWorkbook = Workbook()

#Load the source Excel workbook
sourceWorkbook.LoadFromFile("Sample 1.xlsx")

#Get the first worksheet of the source workbook
sourceSheet = sourceWorkbook.Worksheets[0]

#Get the name of the first worksheet
sheetName = sourceSheet.Name + "_Copy"

#Initialize an instance of the Workbook class
destWorkbook = Workbook()

 #Load the destination Excel workbook
destWorkbook.LoadFromFile("Sample 2.xlsx")

#Add a new worksheet with a specific name to the destination workbook
destSheet = destWorkbook.Worksheets.Add(sheetName)

#Copy the first worksheet of the source workbook to the new worksheet of the destination workbook
destSheet.CopyFrom(sourceSheet)

#Copy the theme from the source workbook to the destination workbook
destWorkbook.CopyTheme(sourceWorkbook)

#Save the destination workbook to another file
destWorkbook.SaveToFile("Result 2.xlsx", ExcelVersion.Version2013)
sourceWorkbook.Dispose()
destWorkbook.Dispose()

How to Convert between Excel and CSV in Python

Gia — Thu, 21 Sep 2023 06:07:46 +0000

Excel files are a widely used document format with rich tools and features, allowing users to easily create, organize, analyze, and visualize data in tabular form. CSV file, on the other hand, is a simpler file format primarily used for storing tabular data, such as spreadsheets or databases. It consists of plain text where each line represents a row of data, with values separated by commas. Due to its high compatibility, CSV can be easily used and processed in various software applications and operating systems. The conversion between these two document formats is also very practical. Here is some related code sharing.

Tool

Visual Studio Code
Spire.XLS for Python This is an Excel library supporting processing Excel document easily on Python platforms, such as creating Excel, reading Excel, converting Excel to image.

Installation

You can install Spire.XLS for Python in Visual Studio Code by performing the following steps:

First, make sure that you have download and install Python.
Open VS Code, click “Extensions”, search for “Python” and then install it.
Click “Explorer” > “NO FOLRDER OPENED” > “Open Folder”.
Choose a desired folder.
Add a “.py” file to this folder and name it whatever you like.
Click “Terminal” > “New Terminal”.
Last, input the following commands

pip install Spire.XLS-for-Python
pip install plum-dispatch==1.7.4

Sample Codes:

Excel to CSV

from spire.xls import *
from spire.common import *

# Create a Workbook object
workbook = Workbook()

# Load an Excel file
workbook.LoadFromFile("sample.xlsx")

# Get the first sheet
sheet = workbook.Worksheets[0]

# Convert Excel to CSV 
sheet.SaveToFile("ToCSV.csv", ",", Encoding.get_UTF8())
workbook.Dispose()

In this code, you can convert Excel sheet to CSV format using SaveToFile() method. The "," parameter specifies the delimiter between values, and “Encoding.get_UTF8()” sets the encoding to UTF-8.

CSV to Excel

from spire.xls import *
from spire.common import *

# Create a Workbook object
workbook = Workbook()

# Load a CSV file
workbook.LoadFromFile("sample.csv", ",", 1, 1)

# Get the first sheet
sheet = workbook.Worksheets[0]

# Display numbers as text
sheet.AllocatedRange.IgnoreErrorOptions = IgnoreErrorType.NumberAsText

# Autofit column width
sheet.AllocatedRange.AutoFitColumns()

# Convert CSV to Excel
workbook.SaveToFile("ToExcel.xlsx", ExcelVersion.Version2013)

In this code, the CSV sheet was saved as "ToExcel.xlsx" by calling SaveToFile(). The “ExcelVersion.Version2013” parameter indicates the desired Excel version for compatibility.

Screenshot:

How to Save .DOCX as .XML using C#

Gia — Fri, 15 Sep 2023 05:40:39 +0000

XML is a universal markup language used to store and transfer data. This document format consists of tags, elements, attributes, and text. Converting Word documents to XML format allows you to express the content, format, and structure of the document in the form of tags, allowing for more flexible data processing and exchange.

Tool:

Visual Studio 2022
Free Spire.Doc for .NET This is totally free library, which enables developers to create, edit or convert Word documents on .NET platforms easily.

Installation:

Download and install Free Spire.Doc for .NET.
Create a new C# project in Visual Studio and open it.
Right-click " References " in the " Solution Explorer ".
And then select " Add Reference " > " Browse ".
Find the DLL file in the BIN folder under the installation path and click " OK " to add it as a reference.

Sample Codes:

After importing DLL files to your project, you can refer to the following codes to save Word document as XML file.

using System;
using Spire.Doc;

namespace WordtoXML
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //Create an object of Document class
            Document document = new Document();

            //Load a Word document from disk
            document.LoadFromFile(@"sample.docx");

            //Save the Word document as an XML file
            document.SaveToFile("toXML.xml", FileFormat.Xml);
        }
    }
}

This method also supports converting Word document to other file format, such as XPS, PDF, HTML.

How to Delete PDF Pages in C#

Gia — Thu, 07 Sep 2023 07:50:23 +0000

Compared to other document formats, the PDF document format is more stable and generally difficult to edit or change. However, in our daily work, dealing with PDF documents is essential. For example, by removing duplicate or unnecessary pages from a PDF document, you can simplify the content of the document and provide a better viewing experience for readers. It can save you a lot of effort and time, especially for large documents. This article will share how to delete specified pages in a PDF file through a C# program.

Tool:

Visual Studio 2022
Free Spire.PDF for .NET This is a free version of Spire.PDF for Java, supports editing and converting PDF on .NET platforms freely. You can also download the commercial version from this link and trial it for 30 days.

Installation:

Download and install Free Spire.PDF for .NET.
Create a new C# project and open it.
Right-click " References " in the " Solution Explorer ".
And then select " Add Reference " > " Browse ".
Find the DLL file in the BIN folder under the installation path and click " OK " to add it as a reference.

Sample Code：

using Spire.Pdf;

namespace RemovePage
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a PdfDocument object
            PdfDocument document = new PdfDocument();

            //Load a sample PDF document
            document.LoadFromFile(@"sample.pdf");

            //Remove the second page
            document.Pages.RemoveAt(1);

            //Save the result document
            document.SaveToFile("RemovePages.pdf");
        }
    }
}

First, create a PdfDocument object and load “ sample.pdf ”. And then get the desired page by PdfDocument.Pages property and delete it by using PdfPageCollection.RemoveAt(int index) method. Finally, save the document to another file.

How to convert Word to HTML file format via Java

Gia — Tue, 29 Aug 2023 08:26:44 +0000

Introduction:

An HTML file is a text file, written in Hypertext Markup Language, used to create web pages. It contains information such as the structure, content and style of the web page. Converting Word documents to HTML files can convert text, headings, paragraphs, lists, tables, images and other elements in Word documents into corresponding HTML tags and attributes. This transformation not only makes it easy to publish the content of the document on the web, but also ensures that the document is displayed consistently across different platforms and devices. The related methods are described below.

Preparation

Take IntelliJ IDEA 2018 as an example:

Download Free Spire.Doc for Java from this Link and decompress the package.
Create a new project in IDEA, and then click “File”- “Project Structure” - “Modules” - “Dependencies” in turn.
Choose the “JARs or Directories” under the “+”.
Find the “Spire.Doc.jar” in the lib folder of the decompressed package and import it to the project.

Code:

import com.spire.doc.*;

public class WordToHtml {
    public static void main(String[] args) {

        //Create a Document instance
        Document document = new Document();

        //Load a Word document
        document.loadFromFile("sample.docx");

        //Save the document as HTML 
        document.saveToFile("output/toHtml.html", FileFormat.Html);
    }
}

In this code, the Document instance is first created. Call the loadFromFile() method to load a Word document, and finally save the document as an HTML file through the saveToFile(String fileName, FileFormat fileFormat)method.

saveToFile(String fileName, FileFormat fileFormat)method provided by Free Spire.Doc for Java supports converting Word documents to various documents, such as PDF, Image, XPS.

How to Set Custom Properties for Word Documents in C#

Gia — Fri, 25 Aug 2023 09:31:53 +0000

Document properties are metadata used to describe and identify the characteristics and attributes of a document, typically classified as built-in properties and custom properties. This functionality plays an important role in the management and usage of documents. In addition to regular properties, users can also add custom properties or tags according to their own needs, enabling more flexible document organization and management, thus improving work efficiency. The passage will show you how to sett custom properties for Word in C# programmatically.

Tool:

Visual Studio 2022
Free Spire.Doc for .NET This is totally free library, which enables developers to create, edit or convert Word documents on .NET platforms easily.

Installation:

Download and install Free Spire.Doc for .NET.
Create a new C# project in Visual Studio and open it.
Right-click " References " in the " Solution Explorer ".
And then select " Add Reference " > " Browse ".
Find the DLL file in the BIN folder under the installation path and click " OK " to add it as a reference.

Sample Codes:

After importing DLL files to your project, you can refer to the following codes to add custom properties to Word Documents.

using Spire.Doc;
using System;

namespace CustomDocumentProperties
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Document instance
            Document document = new Document();

            //Load a Word document
            document.LoadFromFile("Sample.docx");

            //Add custom document properties to the document
            CustomDocumentProperties customProperties = document.CustomDocumentProperties;
            customProperties.Add("Document ID", 1);
            customProperties.Add("Authorized", true);
            customProperties.Add("Authorized By", "Sam");
            customProperties.Add("Authorized Date", DateTime.Today);

            //Save the result document
            document.SaveToFile("CustomDocumentProperties.docx", FileFormat.Docx2013);
        }
    }
}

In the above code, a namespace named “CustomDocumentProperties” is first defined.
Within this namespace, create a class named “Program” as the entry point of the program.
In the main function “Main”, we create a “Document” object to represent an instance of a Word document.
Then, load a Word document by using the “LoadFromFile” method.
Next, obtain the “CustomDocumentProperties” object and use the “Add(string, object)” method to add custom properties to the document's custom property collection.
Finally, call the “SaveToFile” method to save the result document.

How to Add Watermarks to PDF in C#

Gia — Thu, 17 Aug 2023 09:31:14 +0000

A watermark is a transparent mark or pattern that is typically used for copyright protection, branding, anti-piracy, and providing additional information. We have previously discussed how to add a watermark to a PDF using Java. This article will demonstrate how to achieve it by using C#.

Tool:

Visual Studio 2022
Free Spire.PDF for .NET

This is a free version of Spire.PDF for Java, supports editing and converting PDF on .NET platforms freely. You can also download the commercial version from this link and trial it for 30 days.

Installation:

Download and install Free Spire.PDF for .NET.
Create a new C# project and open it.
Right-click " References " in the " Solution Explorer ".
And then select " Add Reference " > " Browse ".
Find the DLL file in the BIN folder under the installation path and click " OK " to add it as a reference.

Sample Code:

using System;
using Spire.Pdf;
using Spire.Pdf.Graphics;
using System.Drawing;

namespace AddMultiLineTextWatermark
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a PdfDocument instance
            PdfDocument pdf = new PdfDocument();

            //Load a sample PDF document
            pdf.LoadFromFile(@"sample.pdf");

            //Create a PdfTrueTypeFont object
            PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial", 20f), true);

            //Traverse all the pages
            for (int i = 0; i < pdf.Pages.Count; i++)
            {
                //Call InsertMultiLineTextWatermark() method to add text watermarks to the specified page
                InsertMultiLineTextWatermark(pdf.Pages[i], "Confidential", font, 3, 3);
            }

            //Save the document to another file
            pdf.SaveToFile("Watermark.pdf");
        }

        //Create a custom method to insert multi-line text watermarks to a page
        static void InsertMultiLineTextWatermark(PdfPageBase page, String watermarkText, PdfTrueTypeFont font, int rowNum, int columnNum)
        {
            //Measure the text size
            SizeF textSize = font.MeasureString(watermarkText);

            //Calculate the values of two offset variables, which will be used to calculate the translation amount of coordinate system
            float offset1 = (float)(textSize.Width * System.Math.Sqrt(2) / 4);
            float offset2 = (float)(textSize.Height * System.Math.Sqrt(2) / 4);

            //Create a tile brush
            PdfTilingBrush brush = new PdfTilingBrush(new SizeF(page.ActualSize.Width / columnNum, page.ActualSize.Height / rowNum));
            brush.Graphics.SetTransparency(0.5f);
            brush.Graphics.Save();
            brush.Graphics.TranslateTransform(brush.Size.Width / 2 - offset1 - offset2, brush.Size.Height / 2 + offset1 - offset2);
            brush.Graphics.RotateTransform(-45);

            //Draw watermark text on the tile brush
            brush.Graphics.DrawString(watermarkText, font, PdfBrushes.Violet, 0, 0);
            brush.Graphics.Restore();

            //Draw a rectangle (that covers the whole page) using the tile brush
            page.Canvas.DrawRectangle(brush, new RectangleF(new PointF(0, 0), page.ActualSize));
        }
    }
}

This library also supports adding image watermark to PDF. This article will help you do that.

How to Add Properties to Word Documents in Java

Gia — Wed, 09 Aug 2023 07:54:43 +0000

Document properties provide additional information about documents, such as title, author, subject, keywords, etc., which can help users better manage and classify documents. These properties can be set and viewed in document editing software, or set through code. Take Java code as an example. The following is a detailed introduction on this operation.

Step 1: Download Free Spire.Doc for Java and unzip it.
This a the community version of Spire.Doc for Java and there are some limitations on pages during the process. If you want to get rid of them, download the commercial product from this link and apply for a temporary license.
It supports create or edit Word files independently on Java applications. With it, you can also convert Word to PDF, convert Word to Image, merge Word documents, etc.

Step 2: Create a new Java project.

Step 3: Import “Spire.Doc.jar” to your project
Take IntelliJ IDEA 2018 (jdk 1.8.0) for example.

Click “File”- “Project Structure”- “Modules”- “Dependencies” in turn.
Choose the “JARs or Directories” under the green plus.
Find the “Spire.Doc.jar” in the lib folder of the decompressed package and import it to the project.

Step 4: Sample code.

import com.spire.doc.BuiltinDocumentProperties;
import com.spire.doc.Document;
import com.spire.doc.FileFormat;

public class AddDocumentProperties {
    public static void main(String []args) throws Exception {

        //Create a Document instance
        Document document = new Document();

        //Load a Word document
        document.loadFromFile("Sample.docx");

        //Access the built-in document properties of the document
        BuiltinDocumentProperties standardProperties = document.getBuiltinDocumentProperties();

        //Set the values of specific built-in document properties 
        standardProperties.setTitle("Document Properties");
        standardProperties.setSubject("How to add properties");
        standardProperties.setAuthor("Naomi");
        standardProperties.setCompany("Co., Ltd");
        standardProperties.setManager("Michael");
        standardProperties.setCategory("Document");
        standardProperties.setKeywords("Word, Document, Properties");
        standardProperties.setComments("This is a good tutorial.");

        //Save the result document
        document.saveToFile("AddProperties.docx", FileFormat.Docx_2013);
    }
}

In the above code, first create a Document instance and load a Word document. Then, by calling the getBuiltinDocumentProperties() method, you can access the document's built-in document properties. Next, use the set method to individually set the value of specific built-in document properties. Finally, save the modified document as a new file using the Document.saveToFile() method.

How to Insert Image Watermark to PDF Programmatically

Gia — Fri, 14 Jul 2023 07:58:28 +0000

Adding a transparent image overlay to PDF pages serves the dual purpose of enhancing file security and enabling features such as encryption, copyright marking, and more. By selecting appropriate tools or software, you can effortlessly incorporate personalized image watermarks into PDF files, conveniently adjusting their position, size, and transparency according to your requirements. In this article, I will illustrate the step-by-step process of inserting image watermarks into PDF documents using a Java program. Below are the detailed steps.

Step 1, Download Free Spire.PDF for Java and unzip it.
This a the community version of Spire.PDF for Java and there are some limitations on pages during the process. If you want to get rid of the limitations, you can download the commercial product from this link and apply for a temporary license.
It supports create or edit PDF files independently on Java applications. What’s more, you can also convert PDF to Word, merge PDF files, print PDF files using this library.

Step 2, Create a new Java project.

Step 3, Import “Spire.Pdf.jar” to your project
Take IntelliJ IDEA 2018 (jdk 1.8.0) for example.

Click “File”- “Project Structure”- “Modules”- “Dependencies” in turn.
Choose the “JARs or Directories” under the green plus.
Find the “Spire.Pdf.jar” in the lib folder of the decompressed package and import it to the project.

Step 4, Sample code

import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfPageBase;
import com.spire.pdf.graphics.PdfBrush;
import com.spire.pdf.graphics.PdfImage;

import java.awt.*;
import java.awt.image.BufferedImage;

public class insertSingleImageWatermark {
    public static void main(String[] args) {

        //Create a PdfDocument class instance
        PdfDocument pdf = new PdfDocument();

        //Load a PDF file
        pdf.loadFromFile("sample.pdf");

        //Load a picture
        PdfImage image = PdfImage.fromFile("image.png");

        //Get the width and height of the image
        int imageWidth = image.getWidth();
        int imageHeight = image.getHeight();

        //Loop through the pages to insert watermark
        for (int i = 0; i < pdf.getPages().getCount(); i++) {

            //Get a page
            PdfPageBase page = pdf.getPages().get(i);

            //Get the width and height of the page
            float pageWidth = (float) (page.getActualSize().getWidth());
            float pageHeight = (float) (page.getActualSize().getHeight());

            //Set the transparency of the watermark
            page.getCanvas().setTransparency(0.6f);

            //Draw the watermark picture at the middle of the page
            page.getCanvas().drawImage(image, pageWidth/1.5 - imageWidth/2, pageHeight/1.5 - imageHeight/2, imageWidth, imageHeight);
        }

        //Save the file
        pdf.saveToFile("ImageWatermark.pdf");
    }
}