JAVA WEB BROWSER

---

import java.net.*;
import java.awt.*;
import java.awt.event.*;
import com.sun.java.swing.*;
import java.io.*; 
 
//The main class 
public class voyagers implements ActionListener,Runnable  
{ 
 public  final int SCROLLBARS_VERTICAL_ONLY = 1; 
 Thread thread; 
 String resource, host, file, url, ReloadReaderCount; 
 String PrevFileContents,NextFileContent, FileGoGetter; 
 HTTP webconnect; 
 TextField textfield; 
 Frame frame; 
 TextArea textarea; 
 JButton back,forward,home,stop,reload; 
 MenuItem open,save,exits; 
 int Eternal=2; 
 int TextAreaFileNameContent,SavedFileReaderCount;
 int urlLength,slash,count,increment; 
 
//The first function to be called. 
//It creates an object that looks like the voyagers class.
public static void main(String s[]) 
{ 
     voyagers MyBrowser=new voyagers(); 
     MyBrowser.Intializer(); 
}

//This is the initialization method.
//It initializes the various components of the interface.
public void Intializer() 
{
 File creator=new File("UrlHistory");
 creator.mkdir();
 File OldFiles=new File("UrlHistory\\"); 
 String ListOfOldFiles[] = OldFiles.list(); 
 int NumberOfOldFiles = ListOfOldFiles.length; 
 for(int OldFilesCount=0; OldFilesCount< NumberOfOldFiles; OldFilesCount++)
  {
     File DeleteFiles=new File("UrlHistory\\" + ListOfOldFiles[OldFilesCount]);
     DeleteFiles.delete();
  } 
 frame = new Frame("VOYAGER"); 
 frame.setLayout(new BorderLayout()); 
 textfield=new TextField("127.0.0.1",20); 
 textarea =new TextArea("",10,50,SCROLLBARS_VERTICAL_ONLY); 
 textarea.setEditable(false); 
 MenuBar menubar=new MenuBar(); 
 Menu menu = menubar.add(new Menu("File")); 
 open = (MenuItem)menu.add(new MenuItem("Open")); 
 open.addActionListener(this); 
 save = (MenuItem)menu.add(new MenuItem("Save")); 
 save.addActionListener(this); 
 exits = (MenuItem)menu.add(new MenuItem("Exit")); 
 exits.addActionListener(this); 
 menubar.add(menu); 
 JToolBar toolbar = new JToolBar(); 
 back = (JButton)toolbar.add(new JButton("      <<= Back     ")); 
 back.addActionListener(this); 
 back.setEnabled(false); 
 forward = (JButton)toolbar.add(new JButton("   =>> Forward    ")); 
 forward.addActionListener(this); 
 forward.setEnabled(false); 
 home = (JButton)toolbar.add(new JButton("     <<=>>Home     ")); 
 home.addActionListener(this); 
 stop = (JButton)toolbar.add(new JButton("       << Stop >>     ")); 
 stop.addActionListener(this); 
 stop.setEnabled(false); 
 reload = (JButton)toolbar.add(new JButton(" <<=>>  Reload <<=>>")); 
 reload.addActionListener(this); 
 reload.setEnabled(false); 
 frame.add(toolbar,"North"); 
 frame.add(textfield,"South"); 
 textfield.addActionListener(this); 
 frame.add(textarea,"Center"); 
 frame.setMenuBar(menubar); 
 frame.resize(650,450); 
 frame.show(); 
 HomePage(); 
 }
            
//This  method  is self-explanatory.
//It traps all actions performed by the user on the
//various components of the application.
public void actionPerformed(ActionEvent e)   
 {
//This if condition is satisfied whenever any
//action is performed on the  textfield component. 
  if(e.getSource() == textfield) 
   {
    url = ((TextField)e.getSource()).getText(); 
    urlLength = url.length(); 
    thread=new Thread(this); 
    thread.start(); 
   }

//This condition is satisfied whenever the
//user clicks on the  back button on the user interface
  else
  if(e.getSource() == back) 
 {

   { 
    increment =increment - 1; 
    if(increment == 1 || increment == 0) 
    back.setEnabled(false); 
    String TextAreaContent=textarea.getText(); 
    int TextAreaContentLength=TextAreaContent.length(); 
    textarea.replaceText("",0,TextAreaContentLength); 
    forward.setEnabled(true); 
     try 
      { 
       BufferedReader PrevFile = new BufferedReader(new FileReader("UrlHistory\\one"+increment+".html")); 
        while((PrevFileContents=PrevFile.readLine())!= null) 
         { 
          textarea.append(PrevFileContents); 
         }  
      } 
     catch (Exception ex) 
      { 
      }  
   }
   
//This condition is satisfied whenever the
//user clicks on the forward button on the user interface
  else
  if(e.getSource() == forward) 
 {

    back.setEnabled(true); 
    String PrevFilesContentsDeleter=textarea.getText(); 
    int PrevFilesContentsDeleterLength=PrevFilesContentsDeleter.length(); 
    textarea.replaceText("",0,PrevFilesContentsDeleterLength); 
     try 
      { 
       increment = increment+1; 
       BufferedReader NextFile = new BufferedReader(new FileReader("UrlHistory\\one"+increment+".html"));
        while((NextFileContent=NextFile.readLine())!= null) 
         { 
          textarea.append(NextFileContent); 
         } 
        if (increment == count)
         forward.setEnabled(false); 
      }
     catch (Exception ex) 
      { 
      } 
   }
   
//This condition is satisfied whenever the
//user clicks on the home button on the interface
  else
  if(e.getSource() == home) 
   {

    String ScreenCleaner=textarea.getText(); 
    int ScreenCleanersLength=ScreenCleaner.length(); 
    textarea.replaceText("",0,ScreenCleanersLength); 
     try 
      { 
       int HomePageReaderCount; 
       String HomeIPAddress="127.0.0.1"; 
       HTTP HomePageProtocol=new HTTP(HomeIPAddress); 
       String DefaultFile="\\"; 
       String DefaultFileReaderString; 
       InputStream HomePageReader = HomePageProtocol.get(DefaultFile); 
       OutputStream  HomePageSaver=new FileOutputStream("UrlHistory\\one.html"); 
        while((HomePageReaderCount = HomePageReader.read()) != -1) 
         {
          HomePageSaver.write((char)HomePageReaderCount); 
         } 
       BufferedReader HomePageWriter = new BufferedReader(new FileReader("UrlHistory\\one.html")); 
        while((DefaultFileReaderString=HomePageWriter.readLine())!= null) 
         {        
          textarea.append(DefaultFileReaderString); 
         } 
      } 
     catch (Exception s) 
      { 
       ExceptionHandler b = new ExceptionHandler(); 
       b.ServerDown(); 
      } 
   }

//This condition is satisfied whenever the
//user clicks on the stop button of the interface
  else
  if(e.getSource() == stop) 
   {
    stop.setEnabled(false); 
    thread.stop(); 
   }
   
//This condition is satisfied whenever the
//user clicks on the reload button on the interface
  else
  if(e.getSource() == reload) 
   {

    url = textfield.getText(); 
    urlLength = url.length(); 
     try 
      { 
       resource=url.substring(0); 
       slash=resource.indexOf('/'); 
       file=resource.substring(slash); 
       host=resource.substring(0,slash); 
       webconnect=new HTTP(host); 
        if(webconnect!=null) 
         { 
          count = count +1; 
          increment = count; 
          forward.setEnabled(false); 
          InputStream TextAreaFileName = webconnect.get(file); 
          OutputStream  TextAreaFileNameSaver=new FileOutputStream("UrlHistory\\one"+increment+".html"); 
           while((TextAreaFileNameContent= TextAreaFileName.read()) != -1) 
            { 
             TextAreaFileNameSaver.write((char)TextAreaFileNameContent); 
            } 
          String Blanker=textarea.getText(); 
          int BlankerSize=Blanker.length(); 
          textarea.replaceText("",0,BlankerSize); 
          BufferedReader ReloadReader = new BufferedReader(new FileReader("UrlHistory\\one"+increment+".html")); 
           while((ReloadReaderCount=ReloadReader.readLine())!= null) 
            { 
             back.setEnabled(true); 
             textarea.append(ReloadReaderCount); 
             } 
         } 
      } 
               catch(StringIndexOutOfBoundsException io) 
               {
                ExceptionHandler b = new ExceptionHandler(); 
                b.PutSlash();
               }
               catch(FileNotFoundException r) 
               {
               } 
               catch(UnknownHostException h)
               {
               ExceptionHandler b = new ExceptionHandler();
               b.ServerDown();
               } 
               catch(IOException o)
               {
               ExceptionHandler b = new ExceptionHandler();
               b.ServerDown();
               }        
  }
  
//This condition is satisfied whenever the
 //the user selects the menuoption open.
  else
  if (e.getSource() == open) 
   {

    String Disintegrator=textarea.getText(); 
    String directory; 
    int DisintegratorLength=Disintegrator.length(); 
    textarea.replaceText("",0,DisintegratorLength); 
    Frame OpenFrame=new Frame("open"); 
    FileDialog filedialog=new FileDialog(OpenFrame,"parameter",0); 
    filedialog.show(); 
    directory=filedialog.getDirectory(); 
    FileGoGetter=filedialog.getFile(); 
     try 
      { 
       int FileOnDiskSize; 
       String FileOnDiskReader; 
       InputStream FileOnDisk=new FileInputStream(directory+FileGoGetter); 
       OutputStream FileOnDiskSaver=new FileOutputStream("UrlHistory\\parag.html"); 
        while((FileOnDiskSize = FileOnDisk.read()) != -1) 
         { 
          FileOnDiskSaver.write((char)FileOnDiskSize); 
         } 
       BufferedReader FileOnDiskWriter = new BufferedReader(new FileReader("UrlHistory\\parag.html")); 
        while((FileOnDiskReader = FileOnDiskWriter.readLine())!= null) 
         { 
          textarea.append(FileOnDiskReader); 
         } 
      } 
     catch(IOException io) 
       { 
       }    
   } 

//This condition is satisfied whenever the
//the user selects the menuoption save.
  else
  if (e.getSource() == save) 
   {

    String p=new String(); 
    Frame SaveFrame=new Frame("frames"); 
    FileDialog SaveFileDialog=new FileDialog(SaveFrame,"p",1); 
    SaveFileDialog.show(); 
    String SavedFileName; 
    String SavedFileDirectory; 
    SavedFileDirectory=SaveFileDialog.getDirectory(); 
    SavedFileName=SaveFileDialog.getFile(); 
     try 
      { 
       FileInputStream SavedFileReader=new FileInputStream("UrlHistory\\one"+increment+".html"); 
       FileOutputStream SavedFileWriter=new FileOutputStream(SavedFileDirectory+SavedFileName); 
        while(( SavedFileReaderCount= SavedFileReader.read())!= -1) 
         { 
           SavedFileWriter.write((char)SavedFileReaderCount); 
         } 
      } 
     catch(IOException io) 
      { 
      } 
   } 

//This condition is satisfied whenever the
//the user selects the menuoption exit.
  else
  if (e.getSource() == exits) 
   {

    System.exit(0); 
   } 
 } 

//This method is called whenever the user performs
//any action on the textfield component.This method starts
//by finding out the name of the file to be fetched from the server.
//It then connects to the server and gets the file requested by the user.

public void run() 
 { 
  try 
   { 
    resource=url.substring(0); 
    slash=resource.indexOf('/'); 
    file=resource.substring(slash); 
    host=resource.substring(0,slash); 
    webconnect=new HTTP(host); 
     if(webconnect!=null) 
      { 
       count = count +1; 
       increment = count; 
       InputStream WWWFileReader = webconnect.get(file); 
       OutputStream WWWFileWriter=new FileOutputStream("UrlHistory\\one"+increment+".html"); 
        while((TextAreaFileNameContent= WWWFileReader.read()) != -1) 
         { 
          WWWFileWriter.write((char)TextAreaFileNameContent); 
         } 
       BufferedReader WWWScreenWriter = new BufferedReader(new FileReader("UrlHistory\\one"+increment+".html")); 
       String WWWScreenCleaner=textarea.getText(); 
       int WWWScreenCleanerSize=WWWScreenCleaner.length(); 
       textarea.replaceText("",0,WWWScreenCleanerSize); 
        while((ReloadReaderCount=WWWScreenWriter.readLine())!= null) 
         { 
          forward.setEnabled(false); 
          stop.setEnabled(true); 
          reload.setEnabled(true); 
          textarea.append(ReloadReaderCount);
           if(count == 2) 
            back.setEnabled(true); 
         } 
      } 
   } 
  catch(IOException io) 
   { 
    ExceptionHandler b = new ExceptionHandler(); 
    b.ServerDown(); 
   } 
 } 
//This method is called explicitly to get the homepage
//from the localhost machine.It connects to the server running
//on the same machine as this application and gets it's default
//html file.
public void HomePage() 
 { 
  if(Eternal == 2) 
   { 
    int OurDefaultFileCount; 
     try 
      { 
       count=1; 
       increment=count; 
       String Ourselves="127.0.0.1"; 
       HTTP OurUrl=new HTTP(Ourselves); 
       String OurDefaultFile="\\"; 
       String DefaultFileStringReader; 
       InputStream OurDefaultFileReader = OurUrl.get(OurDefaultFile); 
       OutputStream OurDefaultFileWriter=new FileOutputStream("UrlHistory\\one"+increment+".html"); 
        while((OurDefaultFileCount= OurDefaultFileReader.read()) != -1) 
         { 
          OurDefaultFileWriter.write((char)OurDefaultFileCount); 
         } 
       BufferedReader DefaultFileScreenWriter = new BufferedReader(new FileReader("UrlHistory\\one"+increment+".html")); 
        while((DefaultFileStringReader=DefaultFileScreenWriter.readLine())!= null) 
         { 
          textarea.append(DefaultFileStringReader); 
         } 
      } 
     catch (Exception e) 
      { 
       ExceptionHandler b = new ExceptionHandler(); 
       b.ServerDown(); 
      } 
    Eternal=3; 
   } 
 } 
}


//This is the class which has the actual code for getting  
//connected to any server.
class HTTP 
{ 
 public final static int HTTP_PORT=80; 
 InetAddress wwwserver; 
 DataInputStream FinalReader; 
 PrintStream FinalPrinter; 
 String response;
//This constructor is called automatically whenever any
//object of the said class is created. This constructor performs a simple
//thing.It gets the name of the server machine from which
//the html file has to be fetched.
 public HTTP(String Server) throws UnknownHostException
  { 
   wwwserver=InetAddress.getByName(Server); 
  } 
//This method gets the html file from the server. It creates
//a socket which is then used to get connected to the server
//machine.Once connected,it makes use of the stream classes 
//to get the contents of the html file.
 public InputStream get(String filename) throws IOException
  { 
   Socket socket; 
   InputStream InitialReader; 
   OutputStream InitialWriter; 
   socket= new Socket(wwwserver,HTTP_PORT); 
    if(socket==null) 
     { 
      return null; 
     } 
   InitialReader=socket.getInputStream(); 
   InitialWriter=socket.getOutputStream(); 
   FinalReader=new DataInputStream(InitialReader); 
   FinalPrinter=new PrintStream(InitialWriter); 
    if(InitialReader==null || InitialWriter==null) 
     { 
      return null; 
     } 
   FinalPrinter.println("GET " + filename + " HTTP/1.0\n"); 
    while((response=FinalReader.readLine()).length() > 0) 
     { 
      if(response.startsWith("HTTP/1.0 404 Not Found")) 
       { 
        ExceptionHandler ErrorFile=new ExceptionHandler(); 
        ErrorFile.FileNotFound(); 
       } 
     }  
   return FinalReader; 
  } 
} 
//This class declares the functions which implement native code
//These functions are called whenever an exception occurs and a
//MessageBox with an appropriate error message is displayed.
class ExceptionHandler
 {                            
 public native void ServerDown();
 public native void FileNotFound();
 public native void PutSlash();
//This constructor loads the new.dll which contains
//the actual code for the above mentioned functions. 
 public ExceptionHandler()
  { 
   System.loadLibrary("new"); 
  } 
 }



//End of the Java Browser.

THE DLL FROM MICROFT'S BACKYARD.

//Before trying this program click here to look at
the change you have to make to you Workspace. For creation
purpose let's open a '.c' file under Windows and name it
'new.c'. Type in the following code.


#include <windows.h>

void *Java_ExceptionHandler_ServerDown_stub(void * p)
{       
	MessageBox(0,"SERVER DOWN OR NOT REACHABLE","ERROR ERROR !!",0);
        return p;
}

void *Java_ExceptionHandler_FileNotFound_stub(void * r)
{			
	MessageBox(0,"404 FILE NOT FOUND","ERROR ERROR !!",0);
        return r;
}

void *Java_ExceptionHandler_PutSlash_stub(void * s)
{       
	MessageBox(0,"PLEASE PUT A SLASH AT THE END OF THE URL NAME","ERROR ERROR !!",0);
        return s;
}

//End of the ".c" file. 

THE DEF FILE.


//Mere creation of the ".c" file is not enough. You have
to create a ".def" before you build your project workspace.
This ".def" file which we shall name as new.def. Now type
in the following code.


LIBRARY     new
EXPORTS
     Java_ExceptionHandler_ServerDown_stub
     Java_ExceptionHandler_FileNotFound_stub
     Java_ExceptionHandler_PutSlash_stub

//Friends, this is the program in its entirety. You can now
include the def file into your project workspace and build
the ".c" file. If everything is correct you would see that
in the debug directory of your workspace you will find a DLL
called as new.dll copy this DLL into the directory where you
have written the Java Program and build the java program using
the the following command

javac voyagers.java

//Now run the program using the following command

java voyagers

//Your Java Browser is now ready to work on the Internet.


Click here to DOWNLOAD the source code.


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