20110902 Java 練習小記

Swing

• 元件 ( JComponent )
  • Swing 的零件
  • JLabel
    • 標籤
      • lb.setText("歡迎光臨");
      • 顯示文字
  • JButton
    • 按鈕
      • bt = new JButton("購買");
• 容器 ( Container )
  • 包含元件的元件
  • Applet 就是容器
    • Applet 中會有一個 內容窗格 ( content pane ) 的中間容器, 並進行新增元件的處理
  • add(元件);
    • 將元件加入到容器
  • add(元件, BorderLayout.位置);
    • 將元件加入到容器
    • 指定元件位置
      • BorderLayout.NORTH
      • BorderLayout.SOUTH
• 事件 ( Event )
• 事件處理 ( event hadling )
• 事件來源 ( event source )
• 傾聽者 ( listener )
• 負責處理事件的類別
• bt.addActionListener( new SampleActionListener());
• mouseClicked
  • 按下滑鼠
• mouseEntered
  • 滑鼠進入範圍
• mouseExited
• 滑鼠離開範圍

package chapter19;

//撰寫 Swing Applet

import javax.swing.*;

public class Sample1 extends JApplet

{

private JLabel lb;

public void init()

{

//建立元件 製作一個標籤

lb = new JLabel();

//設定元件

lb.setText("歡迎光臨");

//新增到容器中

add(lb);

}

}

package chapter19;

//使用 JButton 按鈕元件

import javax.swing.*;

public class Sample2 extends JApplet

{

private JButton bt;

public void init()

{

//建立元件

bt = new JButton("購買");

//新增到容器中

add(bt);

}

}

package chapter19;

//將元件上下並排

import java.awt.BorderLayout;

import javax.swing.*;

public class Sample3 extends JApplet

{

private JLabel lb;

private JButton bt;

public void init()

{

//建立元件

lb = new JLabel("歡迎光臨");

bt = new JButton("購買");

//新增到容器內

//指定元件位置

add(lb, BorderLayout.NORTH);

add(bt, BorderLayout.SOUTH);

}

}

package chapter19;

//進行事件處理

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

public class Sample4 extends JApplet

{

private JLabel lb;

private JButton bt;

public void init()

{

//建立元件

lb = new JLabel("歡迎光臨");

bt = new JButton("購買");

//新增到容器中

add(lb, BorderLayout.NORTH);

add(bt, BorderLayout.SOUTH);

//登錄 listener, 需要配合下面建立的類別

bt.addActionListener(new SampleActionListener());

}

class SampleActionListener implements ActionListener

{

public void actionPerformed( ActionEvent e)

{

lb.setText("謝謝惠顧");

}

}

}

package chapter19;

//點選滑鼠行為處理

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Sample5 extends JApplet

{

private JLabel lb;

public void init()

{

//建立元件

lb = new JLabel("歡迎光臨");

//新增到容器中

add(lb, BorderLayout.NORTH);

//登錄listener

addMouseListener(new SampleMouseListener());

}

//新增一個 listener 類別

class SampleMouseListener extends MouseAdapter

{

public void mouseClicked(MouseEvent e)

{

lb.setText("謝謝惠顧");

}

}

}

package chapter19;

//滑鼠進出的處理

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Sample6 extends JApplet

{

private JLabel lb;

public void init()

{

//建立元件

lb = new JLabel("您好");

//新增到容器中

add(lb, BorderLayout.NORTH);

//登錄 listener

addMouseListener(new SampleMouseListener());

}

class SampleMouseListener extends MouseAdapter

{

public void mouseEntered(MouseEvent e)

{

lb.setText("歡迎光臨");

}

public void mouseExited(MouseEvent e)

{

lb.setText("您好");

}

}

}

package chapter19;

//輸入按鍵時進行處理

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Sample7 extends JApplet

{

private JLabel lb1, lb2;

public void init()

{

//建立元件

lb1 = new JLabel("請選擇方向鍵");

lb2 = new JLabel();

//新增到容器中

add(lb1, BorderLayout.NORTH);

add(lb2, BorderLayout.SOUTH);

//登錄 listener

addKeyListener(new SampleKeyListener());

}

class SampleKeyListener extends KeyAdapter

{

public void keyPressed(KeyEvent e)

{

String str;

//取得輸入按鍵

int k = e.getKeyCode();

switch(k)

{

case KeyEvent.VK_UP:

str = "上"; 

break;

case KeyEvent.VK_DOWN:

str = "下";

break;

case KeyEvent.VK_LEFT:

str = "左";

break;

case KeyEvent.VK_RIGHT:

str = "右";

break;

default:

str = "其他按鍵";

}

lb2.setText(str + ".");

}

}

}