webpageviewer.java

这是一个用于测试用的搜索引擎的案例

package ir.webutils;

/*
 * WebPageViewer.java
 * downloads and displays web pages.
 * June 1, 2001
 * Ted Wild
 */

import java.net.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.awt.*;
import java.io.*;

/**
 * WebPageViewer contains utilities to download and display HTML
 * pages.
 *
 * @author Ted Wild */
public class WebPageViewer {

    private String url;
    private JEditorPane webPagePane;
    private JFrame frame;
    private JTextField locationField;

    public WebPageViewer() {

	// set up the JEditorPane that will display HTML
	initializeWebPagePane();

	// set up the JTextField that will allow user to control the
	// location
	initializeLocationField();

	// set up the layout in a JFrame
	initializeLayout();

	// incantation to display components
	frame.setVisible(true);
    }

    private void initializeWebPagePane() {
	webPagePane = new JEditorPane();

	// Calling setEditable with false causes clicking on links to
	// generate HyperlinkEvents.  Calling setEditable with true
	// allows you to "edit" the pages.
	webPagePane.setEditable(false);

	// Here we add a HyperlinkEventListener that will update the
	// page being viewed.
	webPagePane.addHyperlinkListener(new HyperlinkListener() {
	    
	    public void hyperlinkUpdate(HyperlinkEvent e) {
		
		if (e.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
		    JEditorPane jep = (JEditorPane) e.getSource();

		    try {
			jep.setPage(e.getURL());
			frame.setTitle("WebPageViewer: " + e.getURL());
		    }
		    catch (IOException ex) {
			System.err.println("Unable to view " + 
					   e.getURL() + ": " + ex);
		    }
		}
	    }
	});

	// sets up JEditorPane to handle HTML
	webPagePane.setContentType("text/html");
    }

    private void initializeLocationField() {

	// creates a new JTextField, single argument specifies number
	// of columns
	locationField = new JTextField(20);

	// sets the initial text
	locationField.setText("http://");
	
	// adds a listener that will be called when <Enter> is
	// pressed.  The listener uses the text in the JTextField as a
	// URL and tries to display that URL in the webPagePane.
	locationField.addActionListener(new ActionListener () {

	    public void actionPerformed(ActionEvent e) {
		JTextField f = (JTextField) e.getSource();
		
		try {
		    webPagePane.setPage(f.getText());
		    frame.setTitle("WebPageViewer: " + f.getText());
		}
		catch (IOException ex) {
		    System.err.println("Unable to open " + 
				       f.getText() + ": " + ex);
		}
		
		f.setText("http://");
	    }
	});
    }

    private void initializeLayout() {
	frame = new JFrame("WebPageViewer");

	// To get a scrollbar, all we have to do is put the
	// webPagePane in a JScrollPane.
	JScrollPane scrollPane = new JScrollPane(webPagePane);

	// This causes the program to exit when the JFrame's window is
	// closed.
	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	frame.getContentPane().add(locationField, BorderLayout.NORTH);
	frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
	frame.setSize(640, 720);
    }

    public void displayURL(URL url) {

	try {
	    webPagePane.setPage(url);
	    frame.setTitle(frame.getTitle() + ": " + url);
	}
	catch (IOException e) {
	    System.err.println("Unable to download " + url + ": " + e);
	}
    }

    public static void main(String args[]) {
        
	try {
	    new WebPageViewer().displayURL(new URL("http://www.cs.utexas.edu/users/ml"));
	}
        catch (MalformedURLException e) {
	   
	    // should never occur, url is known not to be malformed.
	}
    }
}