2021-09-23 GUI(练习-打开文件)

import java.awt.FileDialog;
import java.awt.Frame;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.TextArea;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

public class MyMenuTest {

    private Frame f;
    private MenuBar menuBar;
    private Menu menu;
    private MenuItem closeItem, openItem, saveItem;
    private FileDialog openDialog, saveDialog;
    private TextArea textArea;

    public MyMenuTest() {
        init();
    }

    private void init() {
        f = new Frame("my window");
        f.setBounds(300, 100, 500, 650);

        textArea = new TextArea();

        openDialog = new FileDialog(f, "我要打开", FileDialog.LOAD);
        saveDialog = new FileDialog(f, "我要保存", FileDialog.SAVE);

        menuBar = new MenuBar();
        menu = new Menu("文件");

        openItem = new MenuItem("打开");
        saveItem = new MenuItem("保存");
        closeItem = new MenuItem("退出");

        menu.add(openItem);
        menu.add(saveItem);
        menu.add(closeItem);

        menuBar.add(menu);

        f.setMenuBar(menuBar);

        f.add(textArea);

        MyEvent();

        f.setVisible(true);
    }

    private void MyEvent() {

        openItem.addActionListener(e -> {
            openDialog.setVisible(true);
            String fileName = openDialog.getFile();
            String dirPath = openDialog.getDirectory();
            // System.out.println(dirPath + "..." + fileName);

            if (null == fileName || null == dirPath) {
                return;
            }

            textArea.setText("");
            File file = new File(dirPath, fileName);
            try {
                BufferedReader reader = new BufferedReader(new FileReader(file));
                String line = null;
                while ((line = reader.readLine()) != null) {
                    textArea.append(line + "\r\n");
                }
                reader.close();

//                  BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));
//                  byte[] buf = new byte[1024];
//                  int len;
//                  while ((len = in.read(buf)) != -1) {
//                      String s = new String(buf, 0, len);
//                      textArea.append(s + "\r\n");
//                  }
//                  in.close();
            } catch (Exception e2) {
                throw new RuntimeException("读取文件失败");
            }
        });

        closeItem.addActionListener(e -> System.exit(0));

        f.addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }

        });
    }

    public static void main(String[] args) {
        new MyMenuTest();
    }
    
}