San Song Daddy :): October 2023

Automate Form Filling in PDFs Using iText 5 Library in Java

By Errong Leng – 23 Oct 2023 – View online →

Have you ever needed to automatically fill out PDF forms with preset data using a Java application? In this post, we'll explore how to achieve this using the iText 5 library. iText is a popular Java library for creating and manipulating PDF documents, including form filling. We'll walk you through the steps to load an existing PDF form, access form fields, set values, and even flatten the form to make it read-only. Let's get started.

Step 1: Add iText 5 Library

Before we begin, ensure that you have the iText 5 library added to your Java project. You can download the iText 5 JAR files from the official website or use dependency management tools like Maven or Gradle.

Step 2: Load the PDF Form

Load the existing PDF form that you want to fill. You can do this using the PdfReader class in iText:

PdfReader reader = new PdfReader("path/to/your/form.pdf");  PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("path/to/output.pdf"));

Step 3: Access Form Fields

To access form fields in the PDF, you can use the AcroFields class. Set values in the form fields using the setField method:

AcroFields form = stamper.getAcroFields();  form.setField("FieldName1", "Value1");  form.setField("FieldName2", "Value2");  // Set values for other form fields as needed

Replace "FieldName1", "FieldName2", and "Value1", "Value2" with the actual field names and values you want to set.

Step 4: Flatten the Form (Optional)

If you want to make the form read-only after filling it, you can use the setFormFlattening(true) method on the PdfStamper object:

stamper.setFormFlattening(true);

Step 5: Close and Save the PDF

After filling the form fields, close the PdfStamper and save the PDF:

stamper.close();

Your filled PDF will be saved as specified in the output path.

Here's a complete example:

import com.itextpdf.text.pdf.PdfReader;  import com.itextpdf.text.pdf.PdfStamper;  import com.itextpdf.text.pdf.AcroFields;    import java.io.FileOutputStream;    public class PdfFormFiller {      public static void main(String[] args) {          try {              PdfReader reader = new PdfReader("path/to/your/form.pdf");              PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("path/to/output.pdf"));                AcroFields form = stamper.getAcroFields();              form.setField("FieldName1", "Value1");              form.setField("FieldName2", "Value2");              // Set values for other form fields as needed                stamper.setFormFlattening(true);                stamper.close();          } catch (Exception e) {              e.printStackTrace();          }      }  }

This process allows you to automate form filling in PDFs, making it convenient for applications that require bulk data entry or report generation. Just replace file paths and field names/values as needed, and you're ready to go!

Post, Code and Quiet Time.

Efficient File Transfer: Pushing and Pulling Files Between a Spring Boot App and an sFTP Server

By Errong Leng – 23 Oct 2023 – View online →

Photo by Marc Kleen / Unsplash

Are you a developer looking to seamlessly exchange files between your Spring Boot application and an sFTP server? Whether it's pushing files from your app to the server or pulling files from the server to your app, this post will guide you through the process. In this tutorial, we'll cover the steps for both operations to make your file transfers smooth and reliable.

Pushing Files from Spring Boot to sFTP Server

Dependency Setup: First, make sure your Spring Boot project is equipped with the necessary dependencies to interact with an sFTP server. You can add the spring-integration-sftp library to your project.
Configure sFTP Connection: Create a configuration file to set up the sFTP connection parameters, including the host, port, username, and password.
Develop the File Push Logic: Write the Java code to handle file push operations. You can use Spring Integration to create a flow that monitors a local directory for files to be pushed to the sFTP server.
Error Handling: Implement error handling mechanisms to deal with potential issues during the file transfer process. This ensures the reliability of your file transfer operations.
Testing: Thoroughly test the file push functionality to ensure that files are transferred successfully to the sFTP server.

Pulling Files from sFTP Server to Spring Boot

Dependency Setup: Similar to the file push operation, ensure you have the necessary dependencies to interact with the sFTP server.
Configure sFTP Connection: Create a configuration file with the sFTP connection details, just as you did for the file push operation.
Develop the File Pull Logic: Write Java code that monitors the sFTP server for files and pulls them into your Spring Boot application. Again, Spring Integration can be used for this purpose.
Error Handling: Implement error handling to manage issues that may occur during the file retrieval process.
Testing: Rigorously test the file pull functionality to ensure that files are pulled successfully from the sFTP server and stored in your Spring Boot app.

Setting Up a Free sFTP Server

For those looking to get started with sFTP, you can set up a free sFTP server for your development needs. Here are a couple of popular options:

FileZilla Server: FileZilla is a widely used open-source FTP server that also supports sFTP. You can set up FileZilla Server on your local machine or on a dedicated server. Detailed installation and configuration instructions can be found here.
OpenSSH: If you're working on a Unix-based system, you can use OpenSSH as your sFTP server. Most Linux distributions come with OpenSSH pre-installed. You can configure it for sFTP by following instructions specific to your OS.

Code in Java

Below is a Java code example that demonstrates how to set up an sFTP connection using the JSch library, connect via a username and public key authentication, and perform sFTP operations such as pushing a file, pulling a file, and performing an ls (list directory) lookup. Make sure to add the JSch library to your project's dependencies.

import com.jcraft.jsch.*;    public class SftpExample {      public static void main(String[] args) {          String host = "sftp.example.com";          int port = 22;          String username = "your_username";          String privateKeyPath = "/path/to/your/private-key";          String passphrase = "your_passphrase";          String remoteDirectory = "/path/to/remote/directory/";            try {              JSch jsch = new JSch();                // Load the private key              jsch.addIdentity(privateKeyPath, passphrase);                // Create an sFTP session              Session session = jsch.getSession(username, host, port);              session.setConfig("PreferredAuthentications", "publickey,keyboard-interactive,password");              session.setConfig("StrictHostKeyChecking", "no"); // Disable host key checking (for development purposes only)              session.connect();                // Push a file to the remote directory              ChannelSftp channelSftp = (ChannelSftp) session.openChannel("sftp");              channelSftp.connect();              String localFilePath = "/path/to/local/file.txt";              channelSftp.put(localFilePath, remoteDirectory);              channelSftp.disconnect();                // Pull a file from the remote directory              channelSftp = (ChannelSftp) session.openChannel("sftp");              channelSftp.connect();              String remoteFileName = "file.txt"; // The name of the file on the remote server              String localDownloadPath = "/path/to/local/downloaded/file.txt";              channelSftp.get(remoteDirectory + remoteFileName, localDownloadPath);              channelSftp.disconnect();                // List files in the remote directory              channelSftp = (ChannelSftp) session.openChannel("sftp");              channelSftp.connect();              @SuppressWarnings("unchecked")              Vector<ChannelSftp.LsEntry> fileList = channelSftp.ls(remoteDirectory);              for (ChannelSftp.LsEntry entry : fileList) {                  System.out.println(entry.getFilename());              }              channelSftp.disconnect();                // Close the sFTP session              session.disconnect();          } catch (JSchException | SftpException e) {              e.printStackTrace();          }      }  }

Remember to replace placeholders like sftp.example.com, your_username, your_passphrase, and file paths with your actual information. This code connects to the sFTP server, pushes a file, pulls a file, and lists the files in the remote directory. Be cautious about security and best practices when dealing with sensitive data and private keys.

Security Considerations

Remember to secure your sFTP operations by using secure, encrypted connections and ensuring that your credentials are stored and managed securely. Consider using environment-specific properties or secret management tools to keep sensitive information safe.

In conclusion, efficient file transfer between a Spring Boot application and an sFTP server is a crucial part of many systems. By following these steps and best practices, you can ensure that your file transfer operations are reliable and secure. Whether you're pushing files to the server or pulling files from it, the process can be made seamless with the right tools and techniques. Happy coding!

San Song Daddy :)

Automate Form Filling in PDFs Using iText 5 Library in Java

Efficient File Transfer: Pushing and Pulling Files Between a Spring Boot App and an sFTP Server

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