Im trying to make a basic email system in Java. I have a server that the clients connect to and a gui for the clients. When the server picks up a new connection from a client it starts a new thread running that handles all the different operations. The problem is that the server accepts the new client but doesnt start a new client handler thread running. Any help?
public class Server {
public static Connection link;
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
final int PORT = 1234; // Define the sockets and ports and i/o
Socket client;
ClientHandler handler;
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
link = DriverManager.getConnection("jdbc:odbc:emails", "", "");
System.out.println("Connected to Database . . . ");
} catch (ClassNotFoundException cnfEx) {
System.out.println("* Unable to load driver! *");
System.exit(1);
} catch (SQLException sqlEx) {
System.out.println("* Cannot connect to database! *");
System.exit(1);
}
try {
serverSocket = new ServerSocket(PORT); // Set the server socket
} catch (IOException ioEx) {
System.out.println("\nUnable to set up port!"); // If failed let the
// user know
System.exit(1); // Exit the system with error code 1
}
System.out.println("\nServer running...\n"); // Tell the user the server
// is running
do {
client = serverSocket.accept();
// Wait for client.
System.out.println(client);
handler = new ClientHandler(client);
System.out.println(handler);
System.out.println("\nNew client accepted.\n"); // Tell the user the
// server has accepted
// a client
System.out.println("RUNNING");
handler.start(); // Start the handler
} while (true); // Continuous loop
}
static class ClientHandler extends Thread {
/**
*
*/
private Socket client;
private ObjectInputStream input; // Define sockets, i/o and local array
// list
private ObjectOutputStream output;
public ClientHandler(Socket socket) throws IOException // Client handler
// constructor
{
client = socket;
input = new ObjectInputStream(socket.getInputStream());// Set client
// and i/o
// stream
output = new ObjectOutputStream(socket.getOutputStream());
}
public void run() {
String userCommand = null;
System.out.println("RUNNING CLIENT HANDLER");
boolean quit = false;
do {
try {
userCommand = (String) input.readObject();
} catch (IOException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
} catch (ClassNotFoundException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
} // Receive user command
if (userCommand.equals("SEND MESSAGE")) // If user command is to
// send a message
{
String username = null, recipient = null, message = null, insert, fileType = null;
try {
username = (String) input.readObject();
recipient = (String) input.readObject(); // Receive username,
// recipient and
// message
message = (String) input.readObject();
fileType = (String) input.readObject();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
insert = "INSERT INTO [emails] ([From], [To], [Message], [Attachment])"
+ " VALUES('"
+ username
+ "','"
+ recipient
+ "','"
+ message + "','" + fileType + "')";
Statement statement = null;
try {
statement = link.createStatement();
statement.executeUpdate(insert);
link.commit();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
getFile(input, fileType);
} catch (IOException ioEx) {
ioEx.printStackTrace();
} catch (ClassNotFoundException cnfEx) {
cnfEx.printStackTrace();
}
System.out.println(username // Tell the user a message has been
// sent
+ " sent message to " + recipient);
}
if (userCommand.equals("READ MESSAGE")) // If user command is to
// read a message
{
String username = null; // Define local variables
try {
username = (String) input.readObject();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} // Receive the username of the current user
Statement statement = null;
String insert = "SELECT [Email No],[From],[Message],[Attachment] FROM [emails] WHERE To = '"
+ username + "'";
ResultSet rs = null;
try {
statement = link.createStatement();
rs = statement.executeQuery(insert);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
while (rs.next()) {
String from = rs.getString("From");
String message = rs.getString("Message");
String attachment = rs.getString("Attachment");
int emailNo = rs.getInt("Email no");
output.writeObject(from);
output.writeObject(message); // Send the username the
// message is from
output.writeObject(attachment);
output.writeObject(emailNo);
output.flush(); // and the message and flush the output
// stream
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
output.writeObject("END");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} // Send an end message
try {
output.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} // Flush the output stream
System.out.println(username // Tell the user someone is reading
// their messages
+ " reading messages.");
}
if (userCommand.equals("QUIT")) // If the user command is quit
{
quit = true; // Set quit to true
}
if (userCommand.equals("DELETE MESSAGE")) // If the user command is
// delete a message
{
int valueToDelete = 0; // Define local variables
try {
valueToDelete = Integer.parseInt((String) input.readObject());
} catch (NumberFormatException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} // Receive the value to delete
Statement statement = null;
String delete = "DELETE FROM emails WHERE [Email No] = "
+ valueToDelete + "";
try {
statement = link.createStatement();
statement.executeUpdate(delete);
link.commit();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("Deleted message " + valueToDelete); // Tell
// the
// user a
// message
// has
// been
// deleted
}
} while (!quit); // Run while quit is false
System.out.println("Client Closed"); // Tell the user the client has // closed
}
private static void getFile(ObjectInputStream inStream, String fileType)
throws IOException, ClassNotFoundException {
byte[] byteArray = (byte[]) inStream.readObject();
FileOutputStream mediaStream = null;
if (fileType.equals("Text File"))
mediaStream = new FileOutputStream("file.txt");
else if (fileType.equals("Image"))
mediaStream = new FileOutputStream("file.gif");
else if (fileType.equals("Movie"))
mediaStream = new FileOutputStream("file.mpeg");
mediaStream.write(byteArray);
}
}
}
When you are instantiating the ObjectInputStream it will block until the client sends a sufficient header, thus you never get to actually run the thread… See also