GUI 图形化用户界面 监听机制

//疑问：很奇怪，我的D盘下的输入（d:）和（d:\）效果竟然不一样，其他盘的一样
package day22;

import java.awt.Button;
import java.awt.Dialog;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.TextArea;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.File;

public class MyWindowDemo {
	private Frame frame = null;
	private Button btn = null;
	private TextField tf = null;
	private TextArea ta = null;

	private Dialog dl = null;
	private Button dlBtn = null;
	private Label label = null;

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

	MyWindowDemo() {
		init();
	}

	public void init() {
		frame = new Frame("我的小窗");

		// 设置的是什么？
		// tf.setSize(400,20);

		// 设置列数20 列数70
		ta = new TextArea(20, 70);
		tf = new TextField(60);
		btn = new Button("转到");

		frame.setLayout(new FlowLayout());

		frame.setBounds(200, 100, 600, 400);
		btn.setSize(50, 20);

		frame.add(tf);
		frame.add(btn);
		frame.add(ta);

		myEvent();

		frame.setVisible(true);// 此句必须在最后
	}

	private void myEvent() {
		btn.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				getFileNames();
				/*
				 * File dir = new File(dirPath); if(dir.exites() &&
				 * dir.isDirectory()){ ta.setText(""); String[] names =
				 * dir.list(); for(String name:names){ //需要改成\r \n \r\n都可以换行
				 * ta.append(name+"\r\n"); } }
				 */
			}
		});

		frame.addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e) {
				System.exit(0);
			}
		});

		tf.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				System.out.println(e);
				getFileNames();
			}
		});
	}

	private void myDialogEvent() {
		if (dlBtn != null)
			dlBtn.addKeyListener(new KeyAdapter() {
				public void keyPressed(KeyEvent e) {
					if (e.getKeyCode() == KeyEvent.VK_ENTER)
						dl.setVisible(false);
				}
			});

		if (dl != null)
			dl.addWindowListener(new WindowAdapter() {
				public void windowClosing(WindowEvent e) {
					dl.setVisible(false);
				}
			});
	}

	private void getFileNames() {
		ta.setText("");
		String text = tf.getText();
		// ta.setText(text);
		File dir = new File(text);

		if (dir.isDirectory() && dir.exists()) {
			String[] fileNames = dir.list();
			for (String fileName : fileNames) {
				ta.append(fileName + "\r\n");
			}
		} else if (dir.isFile() && dir.exists()) {
			ta.setText(tf.getText());
			tf.setText("");
		} else if (!dir.exists()) {
			dl = new Dialog(frame, "文件提示对话框", true);
			dlBtn = new Button("okButton");
			label = new Label("找不到： " + text + " 。请确认地Internet或地址正确！！");
			// 注意：必须放到前面 dl.setVisible(true)前
			myDialogEvent();
			dl.setLayout(new FlowLayout());
			dl.add(label);
			dl.add(dlBtn);
			dl.setBounds(300, 400, 500, 200);
			dl.setVisible(true);
		}
	}
}