创建型模式之单例模式（多文档窗口）

女爷i 2022-08-09 15:56 209阅读 0赞

题目：使用单例模式设计一个多文档窗口，要求在主窗体中某个内部子窗体只能实例化一次，即只能弹出一个相同的子窗体。

类图

![20151031123636079][]

package cn.factory5;
    
    import java.awt.BorderLayout;
    import java.awt.Container;
    import java.awt.Dimension;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.awt.event.WindowAdapter;
    import java.awt.event.WindowEvent;
    
    import javax.swing.JButton;
    import javax.swing.JDesktopPane;
    import javax.swing.JFrame;
    import javax.swing.JInternalFrame;
    import javax.swing.JTextArea;
    
    
    public class JInternalFrameDemo extends JFrame implements ActionListener {
    	
    	private static JInternalFrame1 internalFrame;
    	Container contentPane = this.getContentPane();
    	
    	public JInternalFrameDemo(){
    		super("主窗体");		
    		contentPane.setLayout(new BorderLayout());
    		JButton button = new JButton("创建一个子窗体");
    		button.addActionListener(this);
    		contentPane.add(button, BorderLayout.SOUTH);	
    		this.setSize(new Dimension(300, 300));
    		this.setVisible(true);
    		this.addWindowListener(new WindowAdapter() {
    			@Override
    			public void windowClosing(WindowEvent e) {
    				System.exit(0);
    			}
    		});
    	}
    	public void actionPerformed(ActionEvent e) {		
    		internalFrame = JInternalFrame1.getJInternalFrame1("子窗体"
    				, true, true, true, true);		
    		internalFrame.setSize(new Dimension(200, 200));
    		internalFrame.setVisible(true);
    		JDesktopPane desktopPane = new JDesktopPane();
    		contentPane.add(desktopPane);
    		desktopPane.add(internalFrame);			
    		try {
    			internalFrame.setSelected(true);
    		} catch (java.beans.PropertyVetoException ex) {
    			System.out.println("Exception while selecting");
    		}	
    	}
    }

package cn.factory5;
    
    import javax.swing.JInternalFrame;
    
    public class JInternalFrame1 extends JInternalFrame{
    
    	private static JInternalFrame1 JIF1 = null;
    	private JInternalFrame1(String name, boolean b1, boolean b2, boolean b3, boolean b4){
    		super(name, b1, b2, b3, b4);
    	}
    
    	public static JInternalFrame1 getJInternalFrame1(String name, boolean b1, boolean b2, boolean b3, boolean b4){
    		if(JIF1 == null)
    			JIF1 = new JInternalFrame1(name, b1, b2, b3, b4);
    		return JIF1;
    	}
    }

package cn.factory5;
    
    public class Client {
    	public static void main(String args[]){		
    		 new JInternalFrameDemo();		
    	}
    }

Eclipse运行效果图

![20151031123412930][]

[20151031123636079]: /images/20220731/b0323ec5b31d4e7c9bcd94dcd1be0812.png
[20151031123412930]: /images/20220731/94f3d4fa54f9430ebf649efea3a3901d.png