catalog.java

来自「java编程开发技巧与实例的编译测试通过的所有例程」· Java 代码 · 共 116 行

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;
import java.io.*;
import java.net.*;

public class Catalog extends Applet implements ActionListener, ItemListener
{
	private Button orderButton	=	new Button("Order Item");
	private Button submitButton	=	new Button("Submit Order");
	private Button clearButton	=	new Button("Clear Order");
	private java.awt.List catalog	=	new java.awt.List(5);
	private TextArea description	=	new TextArea(5, 40);
	private TextArea orders			=	new TextArea(5, 30);
	private LinkedList data	=	null;
	private CatalogImage theImage	=	new CatalogImage();
	private CatalogOrder theBill	=	new CatalogOrder();
	private CatalogSubmission submission	=	null;
	
	public void init()
	{
		Color color	=	new Color(255, 255, 200);
		Panel items	=	new Panel();
		items.setLayout(new BorderLayout());
		items.add("West", new PanelBox(catalog, "Catalog", color));
		items.add("Center", new PanelBox(orders, "your dorder", color));
		Panel buttons = new Panel();
		buttons.setLayout(new FlowLayout());
		buttons.add(orderButton);
		orderButton.addActionListener(this);
		buttons.add(submitButton);
		submitButton.addActionListener(this);
		buttons.add(clearButton);
		clearButton.addActionListener(this);
		Panel panel	=	new Panel();
		panel.setLayout(new BorderLayout());
		panel.add("West", theImage);
		panel.add("Center", description);
		setLayout(new BorderLayout());
		add("North", items);
		add("Center",new PanelBox(panel, "Description", color));
		add("South", new PanelBox(buttons, "Click a button", color));
		setSize(700, 300);
		//setLocationRelativeTo(this);
		catalog.addActionListener(this);
		catalog.addItemListener(this);
		readCatalog();
	}
	public void readCatalog()
	{
		try
		{
			URL url	=	new URL(getCodeBase(), "catalog.dat");
			BufferedInputStream bin	=	new BufferedInputStream(url.openStream());
			ObjectInputStream in	=	new ObjectInputStream(bin);
			data = (LinkedList)in.readObject();
			for (Iterator iterator = data.iterator(); iterator.hasNext(); )
				catalog.add(((CatalogItem)iterator.next()).getName());
			in.close();
			clearOrders();
		}
		catch	(Exception e)
		{
			catalog.add("not available");
			description.setText("Catalog not available, try again later");
			System.err.println(e);
		}
	}
	public void showDescription(int i)
	{
		CatalogItem item	=	(CatalogItem)data.get(i);
		description.setText(item.toString());
		theImage.setImage(getCodeBase(), item.imageName);
	}
	public void orderItem(int i)
	{
		theBill.add((CatalogItem)data.get(i));
		orders.setText(theBill.toString());
		submitButton.setEnabled(true);
	}
	public void clearOrders()
	{
		theBill	=	new CatalogOrder();
		orders.setText("No items selected for purchasing");
		submitButton.setEnabled(false);
	}
	public void actionPerformed(ActionEvent ae)
	{
		if ((ae.getSource() == orderButton) || (ae.getSource() == catalog))
		{
			if (catalog.getSelectedIndex() >= 0)
				orderItem(catalog.getSelectedIndex());
		}
		else if (ae.getSource() == clearButton)
			clearOrders();
		else if (ae.getSource() == submitButton)
		{
			if (submission == null)
				submission	=	new CatalogSubmission(this, theBill);
			else
				submission.toFront();
		}
	}
	public void itemStateChanged(ItemEvent ie)
	{
		showDescription(catalog.getSelectedIndex());
	}
	public void closeSubmission()
	{
		submission.setVisible(false);
		submission.dispose();
		submission	=	null;
	}
}