MiniBrowser.java Source code

Introduction

Here is the source code for MiniBrowser.java

Source

import java.awt.BorderLayout;
import java.awt.Cursor;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.net.URL;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLFrameHyperlinkEvent;

public class MiniBrowser extends JFrame implements HyperlinkListener {
    private JButton backButton = new JButton("<"), forwardButton = new JButton(">");

    private JTextField locationTextField = new JTextField(35);

    private JEditorPane displayEditorPane = new JEditorPane();

    private ArrayList pageList = new ArrayList();

    public MiniBrowser() {
        setSize(640, 480);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel buttonPanel = new JPanel();
        backButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                actionBack();
            }
        });
        backButton.setEnabled(false);
        buttonPanel.add(backButton);
        forwardButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                actionForward();
            }
        });
        forwardButton.setEnabled(false);
        buttonPanel.add(forwardButton);
        locationTextField.addKeyListener(new KeyAdapter() {
            public void keyReleased(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    actionGo();
                }
            }
        });
        buttonPanel.add(locationTextField);
        JButton goButton = new JButton("GO");
        goButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                actionGo();
            }
        });
        buttonPanel.add(goButton);
        displayEditorPane.setContentType("text/html");
        displayEditorPane.setEditable(false);
        displayEditorPane.addHyperlinkListener(this);

        getContentPane().setLayout(new BorderLayout());
        getContentPane().add(buttonPanel, BorderLayout.NORTH);
        getContentPane().add(new JScrollPane(displayEditorPane), BorderLayout.CENTER);
    }

    private void actionBack() {
        URL currentUrl = displayEditorPane.getPage();
        int pageIndex = pageList.indexOf(currentUrl.toString());
        try {
            showPage(new URL((String) pageList.get(pageIndex - 1)), false);
        } catch (Exception e) {
        }
    }

    private void actionForward() {
        URL currentUrl = displayEditorPane.getPage();
        int pageIndex = pageList.indexOf(currentUrl.toString());
        try {
            showPage(new URL((String) pageList.get(pageIndex + 1)), false);
        } catch (Exception e) {
        }
    }

    private void actionGo() {
        URL verifiedUrl = verifyUrl(locationTextField.getText());
        if (verifiedUrl != null) {
            showPage(verifiedUrl, true);
        } else {
            System.out.println("Invalid URL");
        }
    }

    private URL verifyUrl(String url) {
        if (!url.toLowerCase().startsWith("http://"))
            return null;

        URL verifiedUrl = null;
        try {
            verifiedUrl = new URL(url);
        } catch (Exception e) {
            return null;
        }

        return verifiedUrl;
    }

    private void showPage(URL pageUrl, boolean addToList) {
        try {
            URL currentUrl = displayEditorPane.getPage();
            displayEditorPane.setPage(pageUrl);
            URL newUrl = displayEditorPane.getPage();
            if (addToList) {
                int listSize = pageList.size();
                if (listSize <= 0) {
                    return;
                }
                int pageIndex = pageList.indexOf(currentUrl.toString());
                if (pageIndex >= listSize - 1) {
                    return;
                }
                for (int i = listSize - 1; i > pageIndex; i--) {
                    pageList.remove(i);
                }
                pageList.add(newUrl.toString());
            }
            locationTextField.setText(newUrl.toString());
            updateButtons();
        } catch (Exception e) {
            System.out.println("Unable to load page");
        }
    }

    private void updateButtons() {
        if (pageList.size() < 2) {
            backButton.setEnabled(false);
            forwardButton.setEnabled(false);
        } else {
            URL currentUrl = displayEditorPane.getPage();
            int pageIndex = pageList.indexOf(currentUrl.toString());
            backButton.setEnabled(pageIndex > 0);
            forwardButton.setEnabled(pageIndex < (pageList.size() - 1));
        }
    }

    public void hyperlinkUpdate(HyperlinkEvent event) {
        HyperlinkEvent.EventType eventType = event.getEventType();
        if (eventType == HyperlinkEvent.EventType.ACTIVATED) {
            if (event instanceof HTMLFrameHyperlinkEvent) {
                HTMLFrameHyperlinkEvent linkEvent = (HTMLFrameHyperlinkEvent) event;
                HTMLDocument document = (HTMLDocument) displayEditorPane.getDocument();
                document.processHTMLFrameHyperlinkEvent(linkEvent);
            } else {
                showPage(event.getURL(), true);
            }
        }
    }

    public static void main(String[] args) {
        MiniBrowser browser = new MiniBrowser();
        browser.setVisible(true);
    }
}