import java.awt.BorderLayout;import java.awt.Cursor;import java.awt.Font;import java.awt.GridBagConstraints;import java.awt.GridBagLayout;import java.awt.Insets;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.KeyEvent;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import java.io.BufferedReader;import java.io.FileWriter;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.URL;import java.util.ArrayList;import java.util.HashMap;import java.util.HashSet;import java.util.LinkedHashSet;import java.util.regex.Matcher;import java.util.regex.Pattern; import javax.swing.BorderFactory;import javax.swing.JButton;import javax.swing.JCheckBox;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JMenu;import javax.swing.JMenuBar;import javax.swing.JMenuItem;import javax.swing.JOptionPane;import javax.swing.JPanel;import javax.swing.JProgressBar;import javax.swing.JScrollPane;import javax.swing.JSeparator;import javax.swing.JTable;import javax.swing.JTextField;import javax.swing.table.DefaultTableModel;  public class SearchCrawler extends JFrame {private static final String[] MAX_URLS = { "50", "100", "500", "1000" }; // Cache of robot disallow lists.private HashMap disallowListCache = new HashMap(); // Search GUI controls.private JTextField startTextField; private JComboBox maxComboBox; private JCheckBox limitCheckBox; private JTextField logTextField; private JTextField searchTextField; private JCheckBox caseCheckBox; private JButton searchButton; // Search stats GUI controls.private JLabel crawlingLabel2; private JLabel crawledLabel2; private JLabel toCrawlLabel2; private JProgressBar progressBar; private JLabel matchesLabel2; // Table listing search matches.private JTable table; // Flag for whether or not crawling is underway.private boolean crawling; // Matches log file print writer.private PrintWriter logFileWriter; // Constructor for Search Web Crawler.public SearchCrawler() {// Set application title.setTitle("Search Crawler"); // Set window size.setSize(600, 600); // Handle window closing events.addWindowListener(new WindowAdapter() {public void windowClosing(WindowEvent e) {actionExit();}}); // Set up File menu.JMenuBar menuBar = new JMenuBar();JMenu fileMenu = new JMenu("File");fileMenu.setMnemonic(KeyEvent.VK_F);JMenuItem fileExitMenuItem = new JMenuItem("Exit", KeyEvent.VK_X);fileExitMenuItem.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {actionExit();}});fileMenu.add(fileExitMenuItem);menuBar.add(fileMenu);setJMenuBar(menuBar); // Set up search panel.JPanel searchPanel = new JPanel();GridBagConstraints constraints;GridBagLayout layout = new GridBagLayout();searchPanel.setLayout(layout); JLabel startLabel = new JLabel("Start URL:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(startLabel, constraints);searchPanel.add(startLabel); startTextField = new JTextField();constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 0, 5);layout.setConstraints(startTextField, constraints);searchPanel.add(startTextField); JLabel maxLabel = new JLabel("Max URLs to Crawl:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(maxLabel, constraints);searchPanel.add(maxLabel); maxComboBox = new JComboBox(MAX_URLS);maxComboBox.setEditable(true);constraints = new GridBagConstraints();constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(maxComboBox, constraints);searchPanel.add(maxComboBox); limitCheckBox = new JCheckBox("Limit crawling to Start URL site");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.WEST;constraints.insets = new Insets(0, 10, 0, 0);layout.setConstraints(limitCheckBox, constraints);searchPanel.add(limitCheckBox); JLabel blankLabel = new JLabel();constraints = new GridBagConstraints();constraints.gridwidth = GridBagConstraints.REMAINDER;layout.setConstraints(blankLabel, constraints);searchPanel.add(blankLabel); JLabel logLabel = new JLabel("Matches Log File:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(logLabel, constraints);searchPanel.add(logLabel); String file = System.getProperty("user.dir")+ System.getProperty("file.separator") + "crawler.log";logTextField = new JTextField(file);constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 0, 5);layout.setConstraints(logTextField, constraints);searchPanel.add(logTextField); JLabel searchLabel = new JLabel("Search String:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(searchLabel, constraints);searchPanel.add(searchLabel); searchTextField = new JTextField();constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.insets = new Insets(5, 5, 0, 0);constraints.gridwidth = 2;constraints.weightx = 1.0d;layout.setConstraints(searchTextField, constraints);searchPanel.add(searchTextField); caseCheckBox = new JCheckBox("Case Sensitive");constraints = new GridBagConstraints();constraints.insets = new Insets(5, 5, 0, 5);constraints.gridwidth = GridBagConstraints.REMAINDER;layout.setConstraints(caseCheckBox, constraints);searchPanel.add(caseCheckBox); searchButton = new JButton("Search");searchButton.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {actionSearch();}});constraints = new GridBagConstraints();constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 5, 5);layout.setConstraints(searchButton, constraints);searchPanel.add(searchButton); JSeparator separator = new JSeparator();constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 5, 5);layout.setConstraints(separator, constraints);searchPanel.add(separator); JLabel crawlingLabel1 = new JLabel("Crawling:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(crawlingLabel1, constraints);searchPanel.add(crawlingLabel1); crawlingLabel2 = new JLabel();crawlingLabel2.setFont(crawlingLabel2.getFont().deriveFont(Font.PLAIN));constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 0, 5);layout.setConstraints(crawlingLabel2, constraints);searchPanel.add(crawlingLabel2); JLabel crawledLabel1 = new JLabel("Crawled URLs:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(crawledLabel1, constraints);searchPanel.add(crawledLabel1); crawledLabel2 = new JLabel();crawledLabel2.setFont(crawledLabel2.getFont().deriveFont(Font.PLAIN));constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 0, 5);layout.setConstraints(crawledLabel2, constraints);searchPanel.add(crawledLabel2); JLabel toCrawlLabel1 = new JLabel("URLs to Crawl:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(toCrawlLabel1, constraints);searchPanel.add(toCrawlLabel1); toCrawlLabel2 = new JLabel();toCrawlLabel2.setFont(toCrawlLabel2.getFont().deriveFont(Font.PLAIN));constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 0, 5);layout.setConstraints(toCrawlLabel2, constraints);searchPanel.add(toCrawlLabel2); JLabel progressLabel = new JLabel("Crawling Progress:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 0, 0);layout.setConstraints(progressLabel, constraints);searchPanel.add(progressLabel); progressBar = new JProgressBar();progressBar.setMinimum(0);progressBar.setStringPainted(true);constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 0, 5);layout.setConstraints(progressBar, constraints);searchPanel.add(progressBar); JLabel matchesLabel1 = new JLabel("Search Matches:");constraints = new GridBagConstraints();constraints.anchor = GridBagConstraints.EAST;constraints.insets = new Insets(5, 5, 10, 0);layout.setConstraints(matchesLabel1, constraints);searchPanel.add(matchesLabel1);matchesLabel2 = new JLabel();matchesLabel2.setFont(matchesLabel2.getFont().deriveFont(Font.PLAIN));constraints = new GridBagConstraints();constraints.fill = GridBagConstraints.HORIZONTAL;constraints.gridwidth = GridBagConstraints.REMAINDER;constraints.insets = new Insets(5, 5, 10, 5);layout.setConstraints(matchesLabel2, constraints);searchPanel.add(matchesLabel2); // Set up matches table.table = new JTable(new DefaultTableModel(new Object[][] {},new String[] { "URL" }) {public boolean isCellEditable(int row, int column) {return false;}}); // Set up Matches panel.JPanel matchesPanel = new JPanel();matchesPanel.setBorder(BorderFactory.createTitledBorder("Matches"));matchesPanel.setLayout(new BorderLayout());matchesPanel.add(new JScrollPane(table), BorderLayout.CENTER); // Add panels to display.getContentPane().setLayout(new BorderLayout());getContentPane().add(searchPanel, BorderLayout.NORTH);getContentPane().add(matchesPanel, BorderLayout.CENTER);} // Exit this program.private void actionExit() {System.exit(0);} // Handle Search/Stop button being clicked.private void actionSearch() {// If stop button clicked, turn crawling flag off.if (crawling) {crawling = false;return;} ArrayList errorList = new ArrayList(); // Validate that start URL has been entered.String startUrl = startTextField.getText().trim();if (startUrl.length() < 1) {errorList.add("Missing Start URL.");}// Verify start URL.else if (verifyUrl(startUrl) == null) {errorList.add("Invalid Start URL.");} // Validate that Max URLs is either empty or is a number.int maxUrls = 0;String max = ((String) maxComboBox.getSelectedItem()).trim();if (max.length() > 0) {try {maxUrls = Integer.parseInt(max);} catch (NumberFormatException e) {}if (maxUrls < 1) {errorList.add("Invalid Max URLs value.");}} // Validate that matches log file has been entered.String logFile = logTextField.getText().trim();if (logFile.length() < 1) {errorList.add("Missing Matches Log File.");} // Validate that search string has been entered.String searchString = searchTextField.getText().trim();if (searchString.length() < 1) {errorList.add("Missing Search String.");} // Show errors, if any, and return.if (errorList.size() > 0) {StringBuffer message = new StringBuffer(); // Concatenate errors into single message.for (int i = 0; i < errorList.size(); i++) {message.append(errorList.get(i));if (i + 1 < errorList.size()) {message.append("\n");}} showError(message.toString());return;} // Remove "www" from start URL if present.startUrl = removeWwwFromUrl(startUrl); // Start the Search Crawler.search(logFile, startUrl, maxUrls, searchString);} private void search(final String logFile, final String startUrl,final int maxUrls, final String searchString) {// Start the search in a new thread.Thread thread = new Thread(new Runnable() {public void run() {// Show hour glass cursor while crawling is under way.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)); // Disable search controls.startTextField.setEnabled(false);maxComboBox.setEnabled(false);limitCheckBox.setEnabled(false);logTextField.setEnabled(false);searchTextField.setEnabled(false);caseCheckBox.setEnabled(false); // Switch Search button to "Stop."searchButton.setText("Stop"); // Reset stats.table.setModel(new DefaultTableModel(new Object[][] {},new String[] { "URL" }) {public boolean isCellEditable(int row, int column) {return false;}});updateStats(startUrl, 0, 0, maxUrls); // Open matches log file.try {logFileWriter = new PrintWriter(new FileWriter(logFile));} catch (Exception e) {showError("Unable to open matches log file.");return;} // Turn crawling flag on.crawling = true; // Perform the actual crawling.crawl(startUrl, maxUrls, limitCheckBox.isSelected(),searchString, caseCheckBox.isSelected()); // Turn crawling flag off.crawling = false; // Close matches log file.try {logFileWriter.close();} catch (Exception e) {showError("Unable to close matches log file.");} // Mark search as done.crawlingLabel2.setText("Done"); // Enable search controls.startTextField.setEnabled(true);maxComboBox.setEnabled(true);limitCheckBox.setEnabled(true);logTextField.setEnabled(true);searchTextField.setEnabled(true);caseCheckBox.setEnabled(true); // Switch search button back to "Search."searchButton.setText("Search"); // Return to default cursor.setCursor(Cursor.getDefaultCursor()); // Show message if search string not found.if (table.getRowCount() == 0) {JOptionPane.showMessageDialog(SearchCrawler.this,"Your Search String was not found. Please try another.","Search String Not Found",JOptionPane.WARNING_MESSAGE);}}});thread.start();} // Show dialog box with error message.private void showError(String message) {JOptionPane.showMessageDialog(this, message, "Error",JOptionPane.ERROR_MESSAGE);} // Update crawling stats.private void updateStats(String crawling, int crawled, int toCrawl,int maxUrls) {crawlingLabel2.setText(crawling);crawledLabel2.setText("" + crawled);toCrawlLabel2.setText("" + toCrawl); // Update progress bar.if (maxUrls == -1) {progressBar.setMaximum(crawled + toCrawl);} else {progressBar.setMaximum(maxUrls);}progressBar.setValue(crawled); matchesLabel2.setText("" + table.getRowCount());} // Add match to matches table and log file.private void addMatch(String url) {// Add URL to matches table.DefaultTableModel model = (DefaultTableModel) table.getModel();model.addRow(new Object[] { url }); // Add URL to matches log file.try {logFileWriter.println(url);} catch (Exception e) {showError("Unable to log match.");}} // Verify URL format.private URL verifyUrl(String url) {// Only allow HTTP URLs.if (!url.toLowerCase().startsWith("http://"))return null; // Verify format of URL.URL verifiedUrl = null;try {verifiedUrl = new URL(url);} catch (Exception e) {return null;} return verifiedUrl;} // Check if robot is allowed to access the given URL.private boolean isRobotAllowed(URL urlToCheck) {String host = urlToCheck.getHost().toLowerCase(); // Retrieve host‘s disallow list from cache.ArrayList disallowList = (ArrayList) disallowListCache.get(host); // If list is not in the cache, download and cache it.if (disallowList == null) {disallowList = new ArrayList(); try {URL robotsFileUrl = new URL("http://" + host + "/robots.txt"); // Open connection to robot file URL for reading.BufferedReader reader = new BufferedReader(new InputStreamReader(robotsFileUrl.openStream())); // Read robot file, creating list of disallowed paths.String line;while ((line = reader.readLine()) != null) {if (line.indexOf("Disallow:") == 0) {String disallowPath = line.substring("Disallow:".length()); // Check disallow path for comments and remove if// present.int commentIndex = disallowPath.indexOf("#");if (commentIndex != -1) {disallowPath = disallowPath.substring(0,commentIndex);} // Remove leading or trailing spaces from disallow path.disallowPath = disallowPath.trim(); // Add disallow path to list.disallowList.add(disallowPath);}} // Add new disallow list to cache.disallowListCache.put(host, disallowList);} catch (Exception e) {/** Assume robot is allowed since an exception is thrown if the* robot file doesn‘t exist.*/return true;}} /** Loop through disallow list to see if crawling is allowed for the* given URL.*/String file = urlToCheck.getFile();for (int i = 0; i < disallowList.size(); i++) {String disallow = (String) disallowList.get(i);if (file.startsWith(disallow)) {return false;}} return true;} // Download page at given URL.private String downloadPage(URL pageUrl) {try {// Open connection to URL for reading.BufferedReader reader = new BufferedReader(new InputStreamReader(pageUrl.openStream())); // Read page into buffer.String line;StringBuffer pageBuffer = new StringBuffer();while ((line = reader.readLine()) != null) {pageBuffer.append(line);} return pageBuffer.toString();} catch (Exception e) {} return null;} // Remove leading "www" from a URL‘s host if present.private String removeWwwFromUrl(String url) {int index = url.indexOf("://www.");if (index != -1) {return url.substring(0, index + 3) + url.substring(index + 7);} return (url);} // Parse through page contents and retrieve links.private ArrayList retrieveLinks(URL pageUrl, String pageContents,HashSet crawledList, boolean limitHost) {// Compile link matching pattern.Pattern p = Pattern.compile("<a\\s+href\\s*=\\s*\"?(.*?)[\" |>]",Pattern.CASE_INSENSITIVE);Matcher m = p.matcher(pageContents); // Create list of link matches.ArrayList linkList = new ArrayList();while (m.find()) {String link = m.group(1).trim(); // Skip empty links.if (link.length() < 1) {continue;} // Skip links that are just page anchors.if (link.charAt(0) == ‘#‘) {continue;} // Skip mailto links.if (link.indexOf("mailto:") != -1) {continue;} // Skip JavaScript links.if (link.toLowerCase().indexOf("javascript") != -1) {continue;} // Prefix absolute and relative URLs if necessary.if (link.indexOf("://") == -1) {// Handle absolute URLs.if (link.charAt(0) == ‘/‘) {link = "http://" + pageUrl.getHost() + link;// Handle relative URLs.} else {String file = pageUrl.getFile();if (file.indexOf(‘/‘) == -1) {link = "http://" + pageUrl.getHost() + "/" + link;} else {String path = file.substring(0,file.lastIndexOf(‘/‘) + 1);link = "http://" + pageUrl.getHost() + path + link;}}} // Remove anchors from link.int index = link.indexOf(‘#‘);if (index != -1) {link = link.substring(0, index);} // Remove leading "www" from URL‘s host if present.link = removeWwwFromUrl(link); // Verify link and skip if invalid.URL verifiedLink = verifyUrl(link);if (verifiedLink == null) {continue;} /** If specified, limit links to those having the same host as the* start URL.*/if (limitHost&& !pageUrl.getHost().toLowerCase().equals(verifiedLink.getHost().toLowerCase())) {continue;} // Skip link if it has already been crawled.if (crawledList.contains(link)) {continue;} // Add link to list.linkList.add(link);} return (linkList);} /** Determine whether or not search string is matched in the given page* contents.*/private boolean searchStringMatches(String pageContents,String searchString, boolean caseSensitive) {String searchContents = pageContents; /** If case-sensitive search, lowercase page contents for comparison.*/if (!caseSensitive) {searchContents = pageContents.toLowerCase();}// Split search string into individual terms.Pattern p = Pattern.compile("[\\s]+");String[] terms = p.split(searchString); // Check to see if each term matches.for (int i = 0; i < terms.length; i++) {if (caseSensitive) {if (searchContents.indexOf(terms[i]) == -1) {return false;}} else {if (searchContents.indexOf(terms[i].toLowerCase()) == -1) {return false;}}} return true;} // Perform the actual crawling, searching for the search string.public void crawl(String startUrl, int maxUrls, boolean limitHost,String searchString, boolean caseSensitive) {// Set up crawl lists.HashSet crawledList = new HashSet();LinkedHashSet toCrawlList = new LinkedHashSet(); // Add start URL to the to crawl list.toCrawlList.add(startUrl); /** Perform actual crawling by looping through the To Crawl list.*/while (crawling && toCrawlList.size() > 0) {/** Check to see if the max URL count has been reached, if it was* specified.*/if (maxUrls != -1) {if (crawledList.size() == maxUrls) {break;}} // Get URL at bottom of the list.String url = (String) toCrawlList.iterator().next();System.out.println(url);// Remove URL from the To Crawl list.toCrawlList.remove(url); // Convert string url to URL object.URL verifiedUrl = verifyUrl(url); // Skip URL if robots are not allowed to access it.if (!isRobotAllowed(verifiedUrl)) {continue;} // Update crawling stats.updateStats(url, crawledList.size(), toCrawlList.size(), maxUrls); // Add page to the crawled list.crawledList.add(url); // Download the page at the given URL.String pageContents = downloadPage(verifiedUrl); /** If the page was downloaded successfully, retrieve all its links* and then see if it contains the search string.*/if (pageContents != null && pageContents.length() > 0) {// Retrieve list of valid links from page.ArrayList links = retrieveLinks(verifiedUrl, pageContents,crawledList, limitHost); // Add links to the To Crawl list.toCrawlList.addAll(links); /** Check if search string is present in page, and if so, record* a match.*/if (searchStringMatches(pageContents, searchString,caseSensitive)) {addMatch(url);}} // Update crawling stats.updateStats(url, crawledList.size(), toCrawlList.size(), maxUrls);}} // Run the Search Crawler.public static void main(String[] args) {SearchCrawler crawler = new SearchCrawler();crawler.show();} // Max URLs drop-down values.}