frameobserver.java

<设计模式-Java语言中的应用> 的源码

import java.awt.Frame;
import java.awt.TextField;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Button;
import java.awt.Graphics;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class FrameObserver extends Frame implements Observer, ActionListener {
    private GraphText textGraph = new GraphText(60);
    private GraphCanvas canvasGraph = new GraphCanvas();
    private Button buttonClose = new Button("Close");

    public FrameObserver() {
        super("FrameObserver");
        setLayout(new BorderLayout());
        setBackground(Color.lightGray);
        textGraph.setEditable(false);
        canvasGraph.setSize(500, 500);
        add(textGraph, BorderLayout.NORTH);
        add(canvasGraph, BorderLayout.CENTER);
        add(buttonClose, BorderLayout.SOUTH);
        buttonClose.addActionListener(this);
        pack();
        show();
    }
    public void actionPerformed(ActionEvent e) {
        System.out.println("" + e);
        System.exit(0);
    }
    public void update(NumberGenerator generator) {
        textGraph.update(generator);
        canvasGraph.update(generator);
    }
}
class GraphText extends TextField implements Observer {
    public GraphText(int columns) {
        super(columns);
    }
    public void update(NumberGenerator generator) {
        int number = generator.getNumber();
        String text = number + ":";
        for (int i = 0; i < number; i++) {
            text += '*';
        }
        setText(text);
    }
}
class GraphCanvas extends Canvas implements Observer {
    private int number;
    public void update(NumberGenerator generator) {
        number = generator.getNumber();
        repaint();
    }
    public void paint(Graphics g) {
        int width = getWidth();
        int height = getHeight();
        g.setColor(Color.white);
        g.fillArc(0, 0, width, height, 0, 360);
        g.setColor(Color.red);
        g.fillArc(0, 0, width, height, 90, - number * 360 / 50);
    }
}