import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.lang.*;
import java.util.Vector;
/**
* The WWWUtility class is the main part of the WWWUtility.
* its responsibility is the UI and the execution of the
* first instance of the SearchEngine class.
* Normally I would hold the UI as a separate class to keep it
* more abstracted from the program and thus more generic but
* for simplicity I kept it here.
**/
public class WWWUtility extends Frame implements
URLLocatedListener , // this interface contains a method that
// will be fired if the search engine locates
// a URL fitting the criteria.
WindowListener , ActionListener
{
public static void main(String argv[])
{
new WWWUtility();
}
/**
* The constructor calls the superclass with the string for the windows
* title.
**/
public WWWUtility()
{
super("WWW utility");
loadUserInterface();
}
/**
* This method is called by the user through the UI, and it creates
* the first instance of the SearchEngine class.
* it accepts the following parameters:
* url - the url to search. You can use a url to refer to a file on your HD too.
* stringToSearch - the search string. You could improve here by accepting a search
* structure which will support advanced boolean searches. It should be very
* simple to implement.
* numberOfServersToBranchTo - if this equals 0 then every link that is not in this
* domain will be ignored. If this number is above 0 then every link that is not
* on this server will be branched to with numberOfServersToBranchTo - 1 as a
* branching factor. This feature gives us a feel of distance.
* The concept of distance can be expanded to include length of URL string or
* number of pages from the source page rather than servers.
**/
public void beginSearch(URL url,String stringToSearch,int numberOfServersToBranchTo)
{
progressIndicator = new ProgressIndicator(this); // create a progress
// indicator for the advance of the search. (ProgressIndicator.java)
progressIndicator.addActionListener(this); // Listen to the progress
// indicators actions. If the user presses the stop
// search button an event will be fired.
searchEngine = new SearchEngine(progressIndicator, url,
numberOfServersToBranchTo, stringToSearch);
// create an instance of the search engine.
searchEngine.addFoundListener(this); // Each search engine will send
// an event to this class if it finds something.
Thread t = new Thread(searchEngine); // put the search engine on a
// new thread.
t.start(); // launch the thread.
}
/**
* the method defined in URLLocatedListener. This method gets called when a
* url is found or with a null parameter when it is time to end the search.
**/
synchronized public void searchStringFoundInURL(URL url)
{
if(url != null)
outputView.add(url.toString());
else
progressIndicator.dispose();
}
/**
* Invoked when actions occur.
* This method is a part of the ActionListener interface.
**/
public void actionPerformed(ActionEvent e)
{
// listening to menu commands.
if((e.getSource() == searchMenu) &&
(e.getActionCommand().equals("Begin search")))
new SearchDialog(this);
if((e.getSource() == fileMenu) &&
(e.getActionCommand().equals("Exit")))
System.exit(0);
if(e.getSource() == progressIndicator)
{
searchEngine.stopSearching();
}
}
/**
* Invoked when a window has been opened.
* This method was created by the WindowListener interface.
**/
public void windowOpened(WindowEvent e)
{
}
/**
* Invoked when a window is in the process of being closed.
* The close operation can be overridden at this point.
* This method was created by the WindowListener interface.
**/
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
/**
* Invoked when a window has been closed.
* This method was created by the WindowListener interface.
**/
public void windowClosed(WindowEvent e)
{
}
/**
* Invoked when a window is iconified.
* This method was created by the WindowListener interface.
**/
public void windowIconified(WindowEvent e)
{
}
/**
* Invoked when a window is de-iconified.
* This method was created by the WindowListener interface.
**/
public void windowDeiconified(WindowEvent e)
{
}
/**
* Invoked when a window is activated.
* This method was created by the WindowListener interface.
**/
public void windowActivated(WindowEvent e)
{
}
/**
* Invoked when a window is de-activated.
* This method was created by the WindowListener interface.
**/
public void windowDeactivated(WindowEvent e)
{
}
/**
* this method sets up the pulldown menu and the list of the URLs that were
found.
* In the AWT one of the most important concepts is the avoidance of using exact
* sizes to define the size of a menu, that is why I added a line at the bottom of the
* window. That line would cause the window to be big enough to contain a line of this
* size without me specifying the actual size.
* This is a slight hack, I could have gotten the size of the font and resized the window
* according to that.
**/
private void loadUserInterface()
{
addWindowListener(this); // so I will know when the windows close
// button is pressed.
setLayout(new BorderLayout());
setMenuBar(menuBar); // attach the menu bar.
menuBar.add(fileMenu);
fileMenu.add("Exit");
menuBar.add(searchMenu);
searchMenu.add("Begin search");
searchMenu.add("Stop search"); // not implemented...
searchMenu.addActionListener(this); // so we can tell when a menu
// option is selected.
helpMenu.addActionListener(this);
fileMenu.addActionListener(this);
add("Center",outputView);
add("South",statusLine);
pack();
show();
}
public static Runtime runtimeInformation = Runtime.getRuntime(); // the
// runtime class is a very important part of the VM.
// Checkout the notes I made of it below.
private Label statusLine = new Label ("Mini HTML search engine, written by Shai Almog 5/97");
private ProgressIndicator progressIndicator; // a dialog for the search's progress.
private SearchEngine searchEngine; // the Search engine in this class.
private List outputView = new List(20,false); // the results of the search appear here.
private Menu fileMenu = new Menu("File"); // the menu items in this program.
private Menu searchMenu = new Menu("Search");
private MenuBar menuBar = new MenuBar();
}
/**
* this internal class implements a dialog for selecting the search options.
* this way I avoided concentrating to much logic into one black box (the
* WWWUtility class).
**/
class SearchDialog extends Dialog implements ActionListener
{
SearchDialog(WWWUtility owner)
{
super(owner,"Search dialog");
this.owner = owner;
loadUserInterface();
}
/**
* Invoked when actions occur.
* This method is a part of the ActionListener interface.
**/
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == beginSearch)
{
// if the begin search button was pressed then check the validity of the
// data in the fields and run the begin search method in the WWWUtility.
dispose();
Integer serverHops;
try
{
// convert the server hops to an integer.
serverHops = Integer.decode(numberOfServersToBranchTo.getText());
owner.beginSearch(new URL(URLToSearch.getText()),
searchString.getText(),
serverHops.intValue());
}
catch (MalformedURLException err)
{
System.out.println("Error in the URL syntax: " + err.getMessage());
}
catch(NumberFormatException err)
{
System.out.println("Error in reading the number of the maximum server hops.");
}
}
if(e.getSource() == cancelSearch)
{
// if cancel was pressed then get rid of this fialog.
dispose();
}
if(e.getSource() == browseFiles)
{
// if browse was pressed then load a file dialog and run set the
// results to the search url field.
FileDialog fileNameToSearch =
new FileDialog(owner,"Select file to search",FileDialog.LOAD);
fileNameToSearch.show();
URLToSearch.setText("file://"+fileNameToSearch.getDirectory() +
fileNameToSearch.getFile());
}
}
/**
* this method sets up the UI for the dialog.
* notice the creation of panels to group the objects.
* BTW The dialog still looks ugly because I have no design taste whatsoever
**/
private void loadUserInterface()
{
setLayout(new GridLayout(4,1)); // the grid layout tries to put the
// objects on a grid similar to a spreadsheet.
beginSearch.addActionListener(this); // listen to when one of the buttons gets pressed.
cancelSearch.addActionListener(this);
browseFiles.addActionListener(this);
// set the three entry fields and their labels.
// each entry field is grouped with its label in one panel so they
// will not get away from one another.
Panel p = new Panel();
p.setLayout(new BorderLayout());
add(p);
p.add("West",new Label("URL:"));
p.add("East",URLToSearch);
p = new Panel();
p.setLayout(new BorderLayout());
add(p);
p.add("West",new Label("Search string:"));
p.add("East",searchString);
p = new Panel();
p.setLayout(new BorderLayout());
add(p);
p.add("West",new Label("Maximum server hops:"));
p.add("East",numberOfServersToBranchTo);
// put the buttons on the bottom of the dialog one after the other.
p = new Panel();
p.setLayout(new FlowLayout());
p.add(cancelSearch);
p.add(browseFiles);
p.add(beginSearch);
add(p);
pack();
show();
}
private WWWUtility owner; // pointer to the WWWUtility both as a
// frame owning this and so we can call
// the search method.
// The entries and buttons to map the search.
private TextField numberOfServersToBranchTo = new TextField("0",40);
private TextField searchString = new TextField("",40);
private TextField URLToSearch = new TextField("http://www.edm2.com/",40);
private Button beginSearch = new Button("Begin search");
private Button browseFiles = new Button("Browse");
private Button cancelSearch = new Button("Cancel");
}