您的是经典的Swing并发问题。解决方案始终如一-在后台线程中运行长时间的代码，例如可以在SwingWorker中找到的代码。
例如，
import java.awt.FlowLayout;import java.beans.PropertyChangeEvent;import java.beans.PropertyChangeListener;import java.io.*;import java.net.HttpURLConnection;import java.net.URL;import java.util.concurrent.ExecutionException;import javax.swing.Jframe;import javax.swing.SwingWorker;import static javax.swing.Jframe.EXIT_ON_CLOSE;import javax.swing.JProgressBar;public class Downloader { public Downloader(String site, File file) { Jframe frm = new Jframe(); final JProgressBar current = new JProgressBar(0, 100); current.setSize(50, 100); current.setValue(0); current.setStringPainted(true); frm.add(current); frm.setVisible(true); frm.setLayout(new FlowLayout()); frm.setSize(50, 100); frm.setDefaultCloseOperation(EXIT_ON_CLOSE); final Worker worker = new Worker(site, file); worker.addPropertyChangeListener(new PropertyChangeListener() { @Override public void propertyChange(PropertyChangeEvent pcEvt) { if ("progress".equals(pcEvt.getPropertyName())) { current.setValue((Integer) pcEvt.getNewValue()); } else if (pcEvt.getNewValue() == SwingWorker.Statevalue.DONE) { try { worker.get(); } catch (InterruptedException | ExecutionException e) { // handle any errors here e.printStackTrace(); } } } }); worker.execute(); }}class Worker extends SwingWorker<Void, Void> { private String site; private File file; public Worker(String site, File file) { this.site = site; this.file = file; } @Override protected Void doInBackground() throws Exception { URL url = new URL(site); HttpURLConnection connection = (HttpURLConnection) url .openConnection(); int filesize = connection.getContentLength(); int totalDataRead = 0; try (java.io.BufferedInputStream in = new java.io.BufferedInputStream( connection.getInputStream())) { java.io.FileOutputStream fos = new java.io.FileOutputStream(file); try (java.io.BufferedOutputStream bout = new BufferedOutputStream( fos, 1024)) { byte[] data = new byte[1024]; int i; while ((i = in.read(data, 0, 1024)) >= 0) { totalDataRead = totalDataRead + i; bout.write(data, 0, i); int percent = (totalDataRead * 100) / filesize; setProgress(percent); } } } return null; }}
