custombean2.java

java模式设计

//package Property;
import java.awt.*;
import java.awt.event.*;
import java.io.Serializable;
import java.beans.*;

public class CustomBean2 extends Canvas implements Serializable {
	//定义关联属性color
	private Color color = Color.red;
	
	//定义一个成员变量changes维护属性变化监听者列表
	private PropertyChangeSupport changes = new PropertyChangeSupport(this);

    public CustomBean2() {
	  setSize(100,100);
	  setBackground(color);
  	}
    public Color getColor() {
	  return color;
	}

	public void setColor(Color newColor) {
	  Color oldColor = color;

	  color = newColor;
	  //当属性变化时，点火一个属性变化事件，将由changes将事件发送到列表中感兴趣的属性变化监听者那里
	  changes.firePropertyChange("color", oldColor, newColor);
	  repaint();
	}
	
    public void paint(Graphics g) {
	  setBackground(color);
	  String tempColor = "red";
	  if (color == Color.red)
	  {
	     tempColor = "red";
	  } else if (color == Color.green)
	  {
		 tempColor = "green";
	  }	
	  Font f1 = new Font("Monospaced",Font.BOLD,20);
	  g.setFont(f1);
	  g.drawString("I am " + tempColor + "!",20,60);
	}
	
	//将属性变化监听者加入changes维护的列表中的方法
	public void addPropertyChangeListener(PropertyChangeListener l){
	  changes.addPropertyChangeListener(l);
	}

	//将属性变化监听者从changes维护列表中删除的方法
	public void removePropertyChangeListener(PropertyChangeListener l) {
	  changes.removePropertyChangeListener(l);
	}
}