In this guide you will learn how to build a PDF editor in JAVA. The idea has come to me when I helped my granddad to submit the declaration to the tax agency, and instead of annually fill the form again and again I used to change a couple of fields by from PDF to DOC and back. It slightly could ruin the layout, and my student license has been expired. Buying extension for any PDF editor or use online resources I did not want, so I decided to build my own editor with Java. It was fun, and I gain a lot of knowledge during working on this project. I hope you will find this useful too.
Find example PDF in src/sample/sample.PDF
- Select file
- Edit document
- Save/pring document and choose a layout of PDF
- Restore document
Firstly, I recommend you to cover this lesson to be able to create an empty JavaFx app. Besides, JavaFx we also need two libraries. (also please adjust VM option to add aditionally javafx.web at the end.)
- PDFtoHTML - to convert PDF file to HTML and be able to edit the document. (see this)
- Jsoup - to parse HTML document and add additional data to elements of this HTML. (see this)
After you have added .jar files to the library of the project. We can start to build our app.
Here are rough steps of what to do:
- In SceneBuilder open .fxml and build a basic layout. For example:
1.1 I generally create three buttons which are responsible for choose the right PDF; store edited file and restore changes.
1.2 The area where we will build our app is called WebView and uses for displaying web-pages. I decided to use WebView for its minimalism rather than use HTMLEditor (but you can use that if you want). - Write a function which will convert .PDF to .HTML.
2.1 I place this function in Controller.java, here is a code (below)
2.2 In the function I create an output "backup.html" to be able to restore it if I ruin pdf while editing.
public static void generateHTMLFromPDF(PDDocument pdf) throws IOException, ParserConfigurationException {
Writer output = new PrintWriter("./src/output/backup.html", StandardCharsets.UTF_8);
new PDFDomTree().writeText(pdf, output);
output.close();
pdf.close();
}- Create an observer menu (choosing files)
3.1 I placed it under choose button (chooserBtn) in initialize() function: (below)
3.2 The reaction is following: when I click a button, Java call file chooser of OS to be able select file. I also limited extensions of files in FileChooser.ExtensionFilter
chooserBtn.setOnAction(actionEvent -> {
FileChooser fileChooser = new FileChooser();
FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("PDF", "*.pdf","*.PDF");
fileChooser.getExtensionFilters().add(extFilter);
File file = fileChooser.showOpenDialog(chooserBtn.getScene().getWindow());
});- Create a class for additional information to DOM objects.
4.1 I create a class named HtmlEditor.java, there I add function EditHTML() which slightly adjust HTML to be editable:
4.2 DOM object can be editable when attribute contenteditable = true, so I place it in the element<BODY>
4.3 I add CSS styling to ignore width which is set inline for each element.
4.4 I add printing formation and hide border of page element.
public String EditHTML() throws IOException {
File input = new File(this.source);
Document doc = Jsoup.parse(input, "UTF-8");
doc.select("body").attr("contenteditable","true");
doc.select("head").prepend("<style type=\"text/css\">div.p{width:auto!important;} .page{border: 1px transparent!important;} @page {\n" +
" size: auto;\n" +
" margin: 0;\n" +
" }\n" +
" @media print {\n" +
" html, body {\n" +
" width: 210mm;\n" +
" height: 297mm; \n" +
" }\n" +
" .page {\n" +
" margin: 0;\n" +
" border: initial;\n" +
" border-radius: initial;\n" +
" width: initial;\n" +
" min-height: initial;\n" +
" box-shadow: initial;\n" +
" background: initial;\n" +
" page-break-after: always;\n" +
" }\n" +
" }");
doc.outputSettings().syntax(Document.OutputSettings.Syntax.xml);
return doc.html();
}- Finish code for choose button:
5.1 Now when file is chosen it is converting to HTML; getting attributes above and display in WebView
chooserBtn.setOnAction(actionEvent -> {
FileChooser fileChooser = new FileChooser();
FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("PDF", "*.pdf","*.PDF");
fileChooser.getExtensionFilters().add(extFilter);
File file = fileChooser.showOpenDialog(chooserBtn.getScene().getWindow());
if (file != null) {
PDDocument pdf = null;
try {
pdf = PDDocument.load(file);
generateHTMLFromPDF(pdf);
HtmlEditor htmlEditor = new HtmlEditor("./src/output/backup.html");
render.loadContent(htmlEditor.EditHTML(),"text/html");
} catch (IOException | ParserConfigurationException e) {
e.printStackTrace();
}
}
});- Finish initialize() function and add reaction to other buttons:
6.1 At the beginning of the function we state WebEngine object
6.2 For reset button we just call backup.html to be viewed in WebEngine again 6.3 For save option (actionBtn) we just call new Print job to be able either print or store it as PDF file
@FXML
void initialize() throws IOException, ParserConfigurationException {
WebEngine render = pdfView.getEngine();
chooserBtn.setOnAction(actionEvent -> {
FileChooser fileChooser = new FileChooser();
FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("PDF", "*.pdf","*.PDF");
fileChooser.getExtensionFilters().add(extFilter);
File file = fileChooser.showOpenDialog(chooserBtn.getScene().getWindow());
if (file != null) {
PDDocument pdf = null;
try {
pdf = PDDocument.load(file);
generateHTMLFromPDF(pdf);
HtmlEditor htmlEditor = new HtmlEditor("./src/output/backup.html");
render.loadContent(htmlEditor.EditHTML(),"text/html");
} catch (IOException | ParserConfigurationException e) {
e.printStackTrace();
}
}
});
actionBtn.setOnAction(actionEvent -> {
System.out.println("Stored file");
PrinterJob job = PrinterJob.createPrinterJob();
job.showPrintDialog(actionBtn.getScene().getWindow());
render.print(job);
job.endJob();
});
resetBtn.setOnAction(actionEvent -> {
HtmlEditor htmlEditor = new HtmlEditor("./src/output/backup.html");
try {
pdfView.getEngine().loadContent(htmlEditor.EditHTML(),"text/html");
} catch (IOException e) {
e.printStackTrace();
}
});
}- It should work!
package sample;
import java.io.*;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ResourceBundle;
import javafx.beans.property.ReadOnlyObjectProperty;
import javafx.fxml.FXML;
import javafx.print.Printer;
import javafx.print.PrinterJob;
import javafx.scene.control.Button;
import javafx.scene.web.HTMLEditor;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebHistory;
import javafx.scene.web.WebView;
import javafx.stage.FileChooser;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.fit.pdfdom.PDFDomTree;
import org.w3c.dom.Document;
import javax.print.PrintService;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
public class Controller {
@FXML
private ResourceBundle resources;
@FXML
private URL location;
@FXML
private WebView pdfView;
@FXML
private Button actionBtn;
@FXML
private Button resetBtn;
@FXML
private Button chooserBtn;
public static void generateHTMLFromPDF(PDDocument pdf) throws IOException, ParserConfigurationException {
Writer output = new PrintWriter("./src/output/backup.html", StandardCharsets.UTF_8);
new PDFDomTree().writeText(pdf, output);
output.close();
pdf.close();
}
@FXML
void initialize() throws IOException, ParserConfigurationException {
WebEngine render = pdfView.getEngine();
chooserBtn.setOnAction(actionEvent -> {
FileChooser fileChooser = new FileChooser();
FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("PDF", "*.pdf","*.PDF");
fileChooser.getExtensionFilters().add(extFilter);
File file = fileChooser.showOpenDialog(chooserBtn.getScene().getWindow());
if (file != null) {
PDDocument pdf = null;
try {
pdf = PDDocument.load(file);
generateHTMLFromPDF(pdf);
HtmlEditor htmlEditor = new HtmlEditor("./src/output/backup.html");
render.loadContent(htmlEditor.EditHTML(),"text/html");
} catch (IOException | ParserConfigurationException e) {
e.printStackTrace();
}
}
});
actionBtn.setOnAction(actionEvent -> {
System.out.println("Stored file");
PrinterJob job = PrinterJob.createPrinterJob();
job.showPrintDialog(actionBtn.getScene().getWindow());
render.print(job);
job.endJob();
});
resetBtn.setOnAction(actionEvent -> {
File tempFile = new File("./src/output/backup.html");
boolean exists = tempFile.exists();
if (exists) {
HtmlEditor htmlEditor = new HtmlEditor("./src/output/backup.html");
try {
pdfView.getEngine().loadContent(htmlEditor.EditHTML(), "text/html");
} catch (IOException e) {
e.printStackTrace();
}
}
});
}
}