Post on 21-Jan-2016
description
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Advanced Java Programming
CSE 7345/5345/ NTU 531Multithreaded/Sockets/Server
Welcome Welcome Back!!!Back!!!
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
claurent@engr.smu.educlaurent@engr.smu.edu
Chantale Laurent-
Rice
Welcome Welcome Back!!!Back!!!
trice75447@aol.comtrice75447@aol.com
Office Hours:by appt12:50pm-1:50pmSIC 353
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
News
• Dr. El-Rewini is looking for someone with Java Swing background.
• See Dr. El-Rewini or call Beth at SIC for more info
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
ServerObjectives:
Use server-side socket communication
Understanding multithreading design
Use methods of the thread class
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Threads
• There are two ways to create new Threads. – One is to declare a class to be a subclass
of Thread, This subclass should override the run method of class Thread, and you can then allocate and start an instance of that class.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
class CreateThread extends Thread{
CreateThread(){
/* Do standard constructor initialization */start();
}public void run(){
/*Do the work this thread was created for */
}}
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
The other way to create a thread is to declare a class that implements Runnable interface.
That class then implements the run method.
An instance of the class can then be allocated (passed as an argument when you’ve creating a thread
object).
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
class CreateThread implements Runnable{
Thread thread;CreateThread(){
/* Do standard constructor initialization */
thread = new Thread(this. “second”); thread.start();
}public void run(){
/*Do the work this thread was created for */
}}
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
See Java in a nutshell chapter 10
I/Opg. 323
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
In class Exercise
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Using Threads to communicate with
Socket/Server
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
This exercise defines a thread for Applet1 which:
listens and processes requests from Server
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Requirements:Client workstations will communicate to the Server by sending a message(s).
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
1. declare the import statements for I/O
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
import java.net.*;import java.io.*;
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
2. Define a new Thread class that starts when you create an instance of it.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Creating a thread
public class Applet1Thread extends Thread
{
}
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
3. Declare the constructor
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
public Applet1Thread () { }
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
4. Take a shot at coding the run() method. Since we are using I/O, the compiler will insist that a try/catch structure.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Do you want the while(true) read loop inside or outside the run?
Why?
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
public void run () { try {
}
catch( ) }
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
“answer the phone”
6. The The “answer the phone” function in Java Socket servers is provided by the ServerSocket class, so instantiate a ServerSocket Object called ss. Designate port 8200 on the ServerSocket constructor, the port number to be called by the Clients.
•
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
instantiate a ServerSocket Object called ss.
open a serverSocket on applet 1
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
ServerSocket ss = new ServerSocket (8200);
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Since we are calling I/O methods, we will have to catch exceptions. Put the try/catch structure inside the while(true loop), and in the catch block print the Exception object but do not
terminate.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
If a client Socket fails during the join processing, we will simply print an error message and then ignore that Client looping back to the top of the while(true) to accept() the next Client that calls.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
// Fill in the blanks.while(true )
{
}
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
7. Now the Server can go into a while(true) loop where it
answers the phone when a Client calls
Parses the Clients’ first message (the joinrequest)
Makes arrangements for continuing communication with the Client
Returns to the top of the loop to process the next Client that calls.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
8. At the top of the while(true) loop, enter the accept() method of the ServerSocket object. The Server thread will wait here until a Client calls. When a connection is made, the accept() method returns the reference to the Socket it has instantiated for this Client.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
/* accept connection from server 2 */ Socket serverSocket2 = ss.accept
();
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
/* Print something if works */
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
System.out.println ("connection from server 2
accepted");
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
9. Once the Server has been created, instantiate to read and
write from the Socket.
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
BufferedReader inServer2 = new BufferedReader (new InputStreamReader
(serverSocket2.getInputStream () ) );
PrintWriter outServer2 = new PrintWriter(serverSocket2.getOutputStream (), true );
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
/* get keywords from server 2 */
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String keywords = inServer2.readLine ();
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perform the search for server 2 by calling the RString.getSearchData used by applet1
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String results =
RString.getSearchData(keywords);
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
/* send search results to server 2 */
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outServer2.println (results);
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
Now it’s time for the catch write the catch structure
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catch (Exception e) { // Print a message }
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
catch (Exception e) { System.out.println (e.getMessage());
}
Liang, Oreilly, Herbert Schildt, Joseph O’Neil, Simon Roberts, IBM Corp
End