Download EchoClient

Echo Client&Server Application
EchoClient
import java.net.*;
import java.io.*;
class EchoClient
{
public static void main(String[] args) throws IOException {
if (args.length < 2) {
System.err.println("Usage: java EchoClient <IP address> <Port
number>");
System.exit(0);
}
BufferedReader in = null;
PrintWriter out = null;
BufferedReader fromUser = null;
Socket sock = null;
try {
sock = new Socket(args[0], Integer.parseInt(args[1]));
// set up the necessary communication channels
in = new BufferedReader(new
InputStreamReader(sock.getInputStream()));
fromUser = new BufferedReader(new
InputStreamReader(System.in));
out = new PrintWriter(sock.getOutputStream(),true);
while (true) {
String line = fromUser.readLine();
if (line == null || line.equals("bye"))
{
out.println("bye");
break;
}
out.println(line);
System.out.println(in.readLine());
}
}
catch (IOException ioe) {
System.err.println(ioe);
}
finally {
if (in != null)
in.close();
if (fromUser != null)
fromUser.close();
if (out != null)
out.close();
if (sock != null)
sock.close();
}
}
}
EchoServer:
import java.net.*;
import java.io.*;
public class EchoServer
{
public static void main(String[] args) throws IOException {
if (args.length < 1) {
System.err.println("Usage: java EchoServer &lt;Port
Number&gt; ");
System.exit(0);
}
ServerSocket sock = null;
try {
// establish the socket
sock = new ServerSocket(Integer.parseInt(args[0]));
/**
* listen for new connection requests.
* when a request arrives, service it
* and resume listening for more requests.
*/
while (true) {
// now listen for connections
Socket client = sock.accept();
// service the connection
ServiceConnection(client);
}
}
catch (IOException ioe) {
System.err.println(ioe);
}
finally {
if (sock != null)
sock.close();
}
}
public static void ServiceConnection(Socket client)
{
BufferedReader networkBin = null;
OutputStreamWriter networkPout = null;
try {
/**
* get the input and output streams associated with the
socket.
*/
networkBin = new BufferedReader(new
InputStreamReader(client.getInputStream()));
networkPout = new
OutputStreamWriter(client.getOutputStream());
/**
* the following successively reads from the input stream and
returns
* what was read. The loop terminates with ^D or the string
"bye\r\n"
* from the input stream.
*/
while (true) {
String line = networkBin.readLine();
if ( (line == null) || line.equals("bye")) {
break;
}
networkPout.write("Server [ "+line+" ]\r\n");
networkPout.flush();
}
}
catch (IOException ioe) {
System.err.println(ioe);
}
finally {
try {
if (networkBin != null)
networkBin.close();
if (networkPout != null)
networkPout.close();
if (client != null)
client.close();
}
catch (IOException ioee) {
System.err.println(ioee);
}
} // end try
} // end ServiceConnection
}
1. Program Execution
Echo Client Server
Compilation
javac EchoServer.java
javac EchoClient.java
Execution
java EchoServer portno(123)
java EchoClient ipaddrofserver(localhost) portno(123)
the character must typed by the client must reflect back at the client....until the
client quits by typing 'bye'
REMOTE COMMAND EXECUTION
RceClient
import java.net.*;
import java.io.*;
class RceClient
{
public static void main(String args[])
{
try
{
DatagramSocket ds=new DatagramSocket(2000);
InetAddress ia=InetAddress.getByName("127.0.0.1");
byte[] msg=new byte[255];
DataInputStream dis = new DataInputStream(System.in);
String ss = dis.readLine();
msg = ss.getBytes();
DatagramPacket dp = new DatagramPacket(msg,msg.length,ia,1000);
ds.send(dp);
}
catch(Exception e)
{
}
}
}
RceServer
import java.io.*;
import java.net.*;
class RceServer
{
public static void main(String args[])
{
try
{
DatagramSocket ds = new DatagramSocket(1000);
byte[] msg = new byte[255];
DatagramPacket dp = new DatagramPacket(msg,msg.length);
ds.receive(dp);
String ss = new String(msg);
System.out.println("The Path is:" + ss);
Runtime rt = Runtime.getRuntime();
Process p = null;
p = rt.exec(ss);
}
catch(Exception e)
{
}
}
}
Program Execution
Compilation
javac RceServer.java
javac RceClient.java
Execution
java RceServer
java RceClient mspaint.exe
Chat Application
//Client Application
import java.net.*;
import java.io.*;
public class Client implements Runnable
{
Socket s;
BufferedReader br;
BufferedWriter bw;
BufferedReader ppp;
String input = null;
public static void main(String arg[])
{
new Client();
}
public void run()
{
try{
s.setSoTimeout(1);
}
catch(Exception e){}
while (true)
{
try{
System.out.println("Server: "+br.readLine());
}
catch (Exception h){}
}
}
public Client()
{
try {
s = new Socket("127.0.0.1",100);
br = new BufferedReader(new
InputStreamReader(s.getInputStream()));
bw = new BufferedWriter(new
OutputStreamWriter(s.getOutputStream()));
ppp = new BufferedReader(new
InputStreamReader(System.in));
Thread th;
th = new Thread(this);
th.start();
bw.write("Hello");
bw.newLine();
bw.flush();
while(true){
input = ppp.readLine();
bw.write(input);
bw.newLine();
bw.flush();
}
}
catch(Exception e){}
}
}
//Server Application
import java.net.*;
import java.io.*;
public class ServerApp implements Runnable
{
ServerSocket s;
Socket s1;
BufferedReader br;
BufferedWriter bw;
BufferedReader ppp;
String input = null;
public void run()
{
try{
s1.setSoTimeout(1);
}
catch(Exception e){}
while (true)
{
try{
System.out.println("Client: "+br.readLine());
}
catch (Exception h){}
}
}
public static void main(String arg[])
{
new ServerApp();
}
public ServerApp()
{
try{
s = new ServerSocket(100);
s1=s.accept();
br = new BufferedReader(new
InputStreamReader(s1.getInputStream()));
bw = new BufferedWriter(new
OutputStreamWriter(s1.getOutputStream()));
ppp = new BufferedReader(new
InputStreamReader(System.in));
Thread th;
th = new Thread(this);
th.start();
while(true){
input = ppp.readLine();
bw.write(input);
bw.newLine();
bw.flush();
}
}catch(Exception e){}
}
}
Program Execution
Chat Application
Compilation
javac ServerApp.java
javac Client.java
Execution
Z:\NetworkLab\Chat>java ServerApp
Client: Hello
Client: hjsdfsdf
dsflkfl
Z:\NetworkLab\Chat>java Client
hjsdfsdf
Server: dsflkfl
Sdffsa
REMOTE COMMAND EXECUTION
RceClient
import java.net.*;
import java.io.*;
class RceClient
{
public static void main(String args[])
{
try
{
DatagramSocket ds=new DatagramSocket(2000);
InetAddress ia=InetAddress.getByName("127.0.0.1");
byte[] msg=new byte[255];
DataInputStream dis = new DataInputStream(System.in);
String ss = dis.readLine();
msg = ss.getBytes();
DatagramPacket dp = new DatagramPacket(msg,msg.length,ia,1000);
ds.send(dp);
}
catch(Exception e)
{
}
}
}
RceServer
import java.io.*;
import java.net.*;
class RceServer
{
public static void main(String args[])
{
try
{
DatagramSocket ds = new DatagramSocket(1000);
byte[] msg = new byte[255];
DatagramPacket dp = new DatagramPacket(msg,msg.length);
ds.receive(dp);
String ss = new String(msg);
System.out.println("The Path is:" + ss);
Runtime rt = Runtime.getRuntime();
Process p = null;
p = rt.exec(ss);
}
catch(Exception e)
{
}
}
}
Program Execution
Compilation
javac RceServer.java
javac RceClient.java
Execution
java RceServer
java RceClient mspaint.exe