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);
}
}
}