Java Swing - 如何使JFileChooser保存文件

import java.awt.BorderLayout;
import java.awt.Desktop;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class Main {
  JTextArea textArea;
  JButton save;
  void initUI() {
    JFrame frame = new JFrame(Main.class.getSimpleName());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    textArea = new JTextArea(24, 80);
    save = new JButton("Save to file");
    save.addActionListener(e -> saveToFile());
    frame.add(new JScrollPane(textArea));
    JPanel buttonPanel = new JPanel();
    buttonPanel.add(save);
    frame.add(buttonPanel, BorderLayout.SOUTH);
    frame.setSize(500, 400);
    frame.setVisible(true);
  }

  protected void saveToFile() {
    JFileChooser fileChooser = new JFileChooser();
    int retval = fileChooser.showSaveDialog(save);
    if (retval == JFileChooser.APPROVE_OPTION) {
      File file = fileChooser.getSelectedFile();
      if (file == null) {
        return;
      }
      if (!file.getName().toLowerCase().endsWith(".txt")) {
        file = new File(file.getParentFile(), file.getName() + ".txt");
      }
      try {
        textArea.write(new OutputStreamWriter(new FileOutputStream(file),
            "utf-8"));
        Desktop.getDesktop().open(file);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }

  public static void main(String[] args) {
    new Main().initUI();
  }
}