Server socket programming in Java This program is a server sided program that accepts the clients requests at a port and socket of the server. programminghomeworkhelp.com is the leading online solution provider for Java Programming assignments. If you are struggling with your scoring in Java Programming Assignments, Homework or Projects then email your requirements at info@programminghomeworkhelp.com and we will ensure excellent grades. Email your Java assignment to info@programminghomeworkhelp.com and distress yourself from the complex Java Programming Assignments.

2. Server socket programming in Java
This program is a server sided program that accepts the clients
requests at a port and socket of the server.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Arrays;
/**
* The file server program.
*
*/
public class FileServer extends NetCommon {
// the port and socket of the server
private ServerSocket server;
/**
* Create the server socket to accept clients at the given port.
* @param port
*/
public FileServer(int port) throws IOException {
server = new ServerSocket(port);
server.setReuseAddress(true);
System.out.println("The File Server is running at port " +
port);
System.out.println("Press Ctrl-D to terminate.n");
}
/**
* Listen on the specified port and accept clients.
* For each client, a new thread is created to handle it.
*/
public void accept() {
while (true) {
try {
Socket client = server.accept();
InetAddress addr = client.getInetAddress();
System.out.println("Info: new client from " +
addr.getHostName());

3. // create a new thread to handle this client
new ClientWorker(client);
} catch (IOException e) {
System.out.println("Warning: " + e.getMessage());
}
}
}
// the internal thread class to handle one client.
private class ClientWorker implements Runnable {
final Socket client;
final Thread thread; // the thread instance
final String name; // the name of the client.
public ClientWorker(Socket client) {
this.client = client;
this.name = client.getInetAddress().getHostName();
this.thread = new Thread(this);
this.thread.start();
}
@Override
public void run() {
try {
// get the input and output stream for the client
InputStream input = client.getInputStream();
OutputStream output = client.getOutputStream();
// read the file request from the client
String request = readString(input);
System.out.println("Info: client " + name + "
request: " + request);
// check which type of request it is
String[] fields = request.split("s+");
if (fields.length != 2
|| !Arrays.asList("upload",
"download").contains(fields[0])) {
System.out.println("Warning: could not
understand request: " + request);
} else {
String fileName = fields[1];
if ("upload".equals(fields[0])) {
// try to upload the file, get the
file size.
upload(input, output, fileName);
} else {

4. // try to download the file
download(input, output, fileName);
}
}
// shutdown the client
client.close();
System.out.println("Info: client " + name + "
closed.");
} catch (IOException e) {
System.out.println(
"Warning: client " + name + " shutdown
unexpectely");
}
}
}
// the client upload the file to the server
private void upload(InputStream input, OutputStream output,
String fileName)
throws IOException
{
// make sure the server can save the file
try {
FileOutputStream fout = new FileOutputStream(new
File(fileName));
// send an OK message to the client
// and read the following bytes from the client to the
file
sendString(output, "OK");
redirect0(input, fout);
fout.close();
} catch (IOException e) {
System.out.println("Warning: could not save into " +
fileName);
// send a FAIL message to the client
sendString(output, "FAIL");
}
}
// the client upload the file to the server
private void download(InputStream input, OutputStream output,
String fileName)
throws IOException
{
// make sure the server can read the file
try {
FileInputStream fin = new FileInputStream(new
File(fileName));
// send an OK message to the client
// and read the following bytes from the client to the
file
sendString(output, "OK");

5. redirect1(fin, output);
fin.close();
} catch (IOException e) {
System.out.println("Warning: could not read " +
fileName);
// send a FAIL message to the client
sendString(output, "FAIL");
}
}
public static void main(String[] args) {
if (args.length != 1) {
System.out.println("Usage: java FileServer <port>");
return;
}
int port = Integer.parseInt(args[0]);
// construct the file server at the given port
try {
new FileServer(port).accept();
} catch (IOException e) {
System.out.println(
"Error: could not start the server at port" +
port);
}
}
}