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| Java program to send image file over network using UDP |
picture (image) from a computer to another via network using UDP protocol and to display it at the receiving end. Simply, this is the java code to make a java application which can send images from one computer to another over a network. The program uses UDP (User Datagram Protocol). For both the computers (on either ends) the same code is enough. This app can act as a image sender or a receiver. The program uses a Progress bar (JProgressBar) to show the progress of the data transfer. Remember, transferring files over UDP is not easy because UDP does not guarantee ordered delivery, and not even successful delivery. So, here in this program, to ensure ordered delivery, the sender sends next chunk of data (DatagramPacket) only after receiving an acknowledgement for last sent packet. For acknowledgement, i used a string "ACK".
import java.awt.Image;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketAddress;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JProgressBar;
import javax.swing.SwingConstants;
import javax.swing.WindowConstants;
import javax.swing.border.EtchedBorder;
import javax.swing.filechooser.FileFilter;
import javax.swing.filechooser.FileNameExtensionFilter;
public class SendFile extends JFrame {
public static int SEND=0;
int mode;
File f;
SendFile pt;
InetAddress hostip;
long filesize;
DatagramSocket sock;
JLabel img=new JLabel("",SwingConstants.CENTER);
JProgressBar jpb=new JProgressBar();
byte[] b;
SocketAddress sa;
public SendFile(int mod,File fi,String ip)
{
mode=mod;
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
pt=this;
setSize(600,480);
setLayout(null);
add(jpb);
jpb.setBounds(5,5,585,30);
add(img);
setResizable(false);
img.setVerticalTextPosition(SwingConstants.CENTER);
img.setHorizontalTextPosition(SwingConstants.CENTER);
img.setBounds(5,40,585,410);
img.setBorder(new EtchedBorder());
jpb.setValue(0);
jpb.setStringPainted(true);
try{
if(mod==0)
{
sock=new DatagramSocket(33780);
f=fi;
filesize=f.length();
img.setText("<HTML><b>Waiting for a connection.<br/>IP: "+InetAddress.getLocalHost().getHostAddress()+"</b></HTML>");
}
else
{
hostip=InetAddress.getByName(ip);
sock=new DatagramSocket();
img.setText("<HTML><b>Trying to connect to the given IP.</b></HTML>");
}
MyThread.start();
}catch(Exception ex){JOptionPane.showMessageDialog(null,ex);System.exit(0);}
}
public static void main(String args[])
{
File ftemp;
int i=JOptionPane.showConfirmDialog(null,"Want ro send a picture?\nYes - Send an Image\nNo - Receive an Image","Send a File?", JOptionPane.YES_NO_OPTION);
if(i==0)
{
JFileChooser jfc=new JFileChooser();
jfc.removeChoosableFileFilter(jfc.getAcceptAllFileFilter());
FileFilter ff=new FileNameExtensionFilter("Image file","jpg","png","bmp","jpeg","gif");
jfc.addChoosableFileFilter(ff);
jfc.setFileSelectionMode(JFileChooser.FILES_ONLY);
jfc.setMultiSelectionEnabled(false);
jfc.setDialogTitle("Select a file to send");
if(jfc.showOpenDialog(null)==JFileChooser.APPROVE_OPTION)
{
ftemp=jfc.getSelectedFile();
new SendFile(0,ftemp,"").setVisible(true);
}
else
{JOptionPane.showMessageDialog(null, "File not Selected");System.exit(0);}
}
else
{
String ip=JOptionPane.showInputDialog("Enter the IP of server");
new SendFile(1,null,ip).setVisible(true);
}
}
Thread MyThread=new Thread()
{
public void run()
{
DatagramPacket p;
String s="";
try{
if(mode==SEND)
{
while(s.startsWith("GETPIC")==false)
{
b=new byte[300];
p=new DatagramPacket(b,300);
sock.setSoTimeout(0);
sock.receive(p);
sa=p.getSocketAddress();
s=new String(b);
}
img.setText("connected to:"+sa);
s=f.getName()+":"+Long.toString(filesize)+"$$";
p=new DatagramPacket(s.getBytes(),s.length(),sa);
sock.send(p);
int l,sendCount;
boolean failed;
sock.setSoTimeout(1000);
FileInputStream fi=new FileInputStream(f);
l=1;
img.setText("Sending image");
for(int i=0;i<filesize;)
{
failed=false;
b=new byte[300];
l=fi.read(b);
sendCount=0;
do
{
p=new DatagramPacket(b,l,sa);
sock.send(p);
sendCount++;
Thread.sleep(80);
try{
sock.receive(p);
s=new String(b);
if(s.contains("ACK")==false)
throw new Exception();
}catch(Exception ex){failed=true;}
}while(failed&&sendCount<5);
if(sendCount<5)
{
i+=l;
jpb.setValue(i*100/(int)filesize);
jpb.setString(Integer.toString(jpb.getValue())+" %");
}
else
{
JOptionPane.showMessageDialog(null, "Client is not receiving");System.exit(0);
}
}
fi.close();
img.setText("Sending complete");
}
else
{
s="GETPIC";
p=new DatagramPacket(s.getBytes(),s.length(),hostip,33780);
sock.send(p);
b=new byte[300];
p=new DatagramPacket(b,300);
sock.receive(p);
s=new String(p.getData());
f=new File(System.getProperty("java.io.tmpdir")+"\\"+s.substring(0,s.indexOf(":")));
filesize=Long.parseLong(s.substring(s.indexOf(":")+1,s.indexOf("$$")));
int i,l;
FileOutputStream fo=new FileOutputStream(f);
b=new byte[300];
sock.setSoTimeout(5000);
img.setText("Receiving image");
for(i=0;i<filesize;)
{
b=new byte[300];
p=new DatagramPacket(b,300);
sock.receive(p);
if(p.getLength()>0)
{
i+=p.getLength();
jpb.setValue(i*100/(int)filesize);
jpb.setString(Integer.toString(jpb.getValue())+" %");
fo.write(p.getData());
s="ACK";
p=new DatagramPacket(s.getBytes(),s.length(),hostip,33780);
sock.send(p);
}
}
fo.close();
img.setIcon(new ImageIcon(new ImageIcon(f.getPath()).getImage().getScaledInstance(img.getWidth(),img.getHeight(),Image.SCALE_SMOOTH)));
img.setText("This is the received image");
}
}catch(Exception ex){}
}
};
}
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