Command模式例子1

import java.awt.Button;   
import java.awt.Color;   
import java.awt.FileDialog;   
import java.awt.Frame;   
import java.awt.Menu;   
import java.awt.MenuBar;   
import java.awt.MenuItem;   
import java.awt.Panel;   
import java.awt.event.ActionEvent;   
import java.awt.event.ActionListener;   
  
public class ActionCommand extends Frame {   
  Menu mnuFile;   
  
  MenuItem mnuOpen, mnuExit;   
  
  Button btnRed;   
  
  Panel p;   
  
  Frame fr;   
  
  //-----------------------------------------   
  public ActionCommand() {   
    super("Frame without commands");   
    fr = this; //sae cop of this frame   
    MenuBar mbar = new MenuBar();   
    setMenuBar(mbar);   
  
    mnuFile = new Menu("File", true);   
    mbar.add(mnuFile);   
  
    mnuOpen = new MenuItem("Open...");   
    mnuFile.add(mnuOpen);   
    mnuExit = new MenuItem("Exit");   
    mnuFile.add(mnuExit);   
  
    mnuOpen.addActionListener(new fileOpen());   
    mnuExit.addActionListener(new fileExit());   
  
    btnRed = new Button("Red");   
    p = new Panel();   
    add(p);   
    p.add(btnRed);   
  
    btnRed.addActionListener(new btnRed());   
    setBounds(100, 100, 200, 100);   
    setVisible(true);   
  }   
  
  //-----------------------------------------   
  private void exitClicked() {   
    System.exit(0);   
  }   
  
  //-----------------------------------------   
  static public void main(String argv[]) {   
    new ActionCommand();   
  }   
  
  //=====----====--inner classes---=====----   
  class fileOpen implements ActionListener {   
    public void actionPerformed(ActionEvent e) {   
      FileDialog fDlg = new FileDialog(fr, "Open a file", FileDialog.LOAD);   
      fDlg.show();   
    }   
  }   
  
  //-------------------------------------   
  class btnRed implements ActionListener {   
    public void actionPerformed(ActionEvent e) {   
      p.setBackground(Color.red);   
    }   
  }   
  
  //-------------------------------------   
  class fileExit implements ActionListener {   
    public void actionPerformed(ActionEvent e) {   
      System.exit(0);   
    }   
  }   
}