You seem to not understand what SwingWorker does.
SwingWorker provides a means by which you can execute long running tasks outside the context of the Event Dispatching Thread. This means that your program won’t appear to have become frozen. The benefit of using a SwingWorker (over using a simple Thread) is that it provides a number of easy to use methods to re-sync the updates back to the EDT, which is indented to stop you from breaking the single thread rules of Swing: No UI element should be created or modified on any thread other then the EDT.
Tak a closer look at Worker Threads and SwingWorker and javax.swing.SwingWorker<T,V> and Concurrency in Swing for more details
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.ExecutionException;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.ImageWriter;
import javax.imageio.event.IIOReadProgressListener;
import javax.imageio.event.IIOWriteProgressListener;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ConvertImage {
public static void main(String[] args) {
new ConvertImage();
}
public ConvertImage() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
TestPane tp = new TestPane();
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(tp);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
tp.convert(new File("/your/image/somewhere"));
}
});
}
public class TestPane extends JPanel implements ImageConverstionListener {
private JLabel label = new JLabel("Waiting...");
private JProgressBar pb = new JProgressBar();
public TestPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(label, gbc);
add(pb, gbc);
}
public void convert(File file) {
ConverterWorker worker = new ConverterWorker(file, this);
worker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(final PropertyChangeEvent evt) {
if ("progress".equalsIgnoreCase(evt.getPropertyName())) {
pb.setValue((int) evt.getNewValue());
}
}
});
worker.execute();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
@Override
public void failedToConvertImage(File source, Throwable cause) {
cause.printStackTrace();
JOptionPane.showMessageDialog(this, "<html>Failed to convert " + source + "<br>" + cause.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
}
@Override
public void imageConverted(File source, byte[] bytes) {
JOptionPane.showMessageDialog(this, "Converted image to " + bytes.length + " bytes", "Converted", JOptionPane.INFORMATION_MESSAGE);
}
@Override
public void setMessage(String msg) {
label.setText(msg);
}
}
public interface ImageConverstionListener {
public void failedToConvertImage(File source, Throwable cause);
public void imageConverted(File source, byte[] bytes);
public void setMessage(String msg);
}
public class ConverterWorker extends SwingWorker<ByteArrayOutputStream, String> {
private File source;
private ImageConverstionListener listener;
public ConverterWorker(File source, ImageConverstionListener listener) {
this.source = source;
this.listener = listener;
}
@Override
protected void process(List<String> chunks) {
listener.setMessage(chunks.get(chunks.size() - 1));
}
@Override
protected ByteArrayOutputStream doInBackground() throws Exception {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
publish("Reading image...");
try (ImageInputStream iis = ImageIO.createImageInputStream(source)) {
Iterator<ImageReader> readers = ImageIO.getImageReaders(iis);
if (readers.hasNext()) {
ImageReader reader = readers.next();
reader.addIIOReadProgressListener(new IIOReadProgressListener() {
@Override
public void sequenceStarted(ImageReader source, int minIndex) {
}
@Override
public void sequenceComplete(ImageReader source) {
}
@Override
public void imageStarted(ImageReader source, int imageIndex) {
}
@Override
public void imageProgress(ImageReader source, float percentageDone) {
setProgress(Math.round(percentageDone));
}
@Override
public void imageComplete(ImageReader source) {
}
@Override
public void thumbnailStarted(ImageReader source, int imageIndex, int thumbnailIndex) {
}
@Override
public void thumbnailProgress(ImageReader source, float percentageDone) {
}
@Override
public void thumbnailComplete(ImageReader source) {
}
@Override
public void readAborted(ImageReader source) {
}
});
reader.setInput(iis);
try {
BufferedImage img = reader.read(0);
publish("Converting image...");
try (ImageOutputStream ios = ImageIO.createImageOutputStream(baos)) {
Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("png");
if (writers.hasNext()) {
ImageWriter writer = writers.next();
writer.addIIOWriteProgressListener(new IIOWriteProgressListener() {
@Override
public void imageStarted(ImageWriter source, int imageIndex) {
}
@Override
public void imageProgress(ImageWriter source, float percentageDone) {
setProgress(Math.round(percentageDone));
}
@Override
public void imageComplete(ImageWriter source) {
}
@Override
public void thumbnailStarted(ImageWriter source, int imageIndex, int thumbnailIndex) {
}
@Override
public void thumbnailProgress(ImageWriter source, float percentageDone) {
}
@Override
public void thumbnailComplete(ImageWriter source) {
}
@Override
public void writeAborted(ImageWriter source) {
}
});
writer.setOutput(ios);
try {
writer.write(img);
} finally {
writer.removeAllIIOWriteProgressListeners();
}
}
}
} finally {
reader.removeAllIIOReadProgressListeners();
}
}
}
return baos;
}
@Override
protected void done() {
try {
ByteArrayOutputStream baos = get();
listener.imageConverted(source, baos.toByteArray());
} catch (InterruptedException | ExecutionException ex) {
listener.failedToConvertImage(source, ex);
}
}
}
}