A client server multichat program for network programming

This was like my 4th year's network programming lab's project. The main task is to create a server that will help some clients to make communication with each other, like any social media services like Facebook, Whatsapp, Messenger etc.

Software Used: XAMPP server, NetBeans IDE.

Codes, sql files are given in the folder. Create a database in XAMPP named multichat. Then import the sql file. These are the instructions for the program: 

• 1. Type 'create User_name Password' to create an account 
• 2. Type 'login User_name Password' to login your account
• 3. Type 'logout' to logout from your account 
• 4. Type 'joinchatroom Chat_room_name' to join a chatroom 
• 5. Type 'leavechatroom' to leave from your current chatroom
• 6. Type 'showchatroom' to show all available chat rooms 
• 7. Type 'showuser' to show all logged in user available
• 8. Type 'showfriend' to show your friend list 
• 9. Type 'showrequest' to show your pending friend request 
• 10. Type 'connect Friend_name' to send friend request to your friend
• 11. Type 'yes Friend_name' to accept a friend request 
• 12. Type 'no Friend_name' to reject a friend request 
• 13. Type 'message Friend_name Message' to send private message to your friend 
• 14. Type anything else besides these commands to chat with your friends :)

At first, run the Xampp and start apache and sql connection, then run the server.java in the server project and after that we can run client.java as many ( I set at most 50 user ) times to create new client that can communicate.

Snapshots of the project

Firstly we will create a user using ‘create’ command like this:

Be careful about spacing. Ok, now login part:

The username is incorrect. Same thing goes for incorrect password too.

Now we are logged in. All the other commands are similar like this. Commands: 

• 1. create: creates an user account in the database. 
• 2. login: login command requires three space separated strings. If not found three strings, then it will show invalid command in the console. If the user is already logged in, then it will also show already logged in. Else command will check username and password from client table in the database and the user will be online. 
• 3. logout: logout will sign out the user from the program.
• 4. joinchatroom: The user will be able to join a chat room using this command as follows:

**If there are already people in a chat room, and they are online; if then a person joins that chat room, every other members of that room (currently logged in) will receive a message to welcome the new user 

• 5. leavechatroom: User can leave his chat room. User can enter another chat room using joinchatroom command. If he is already in a chat room, then he will automatically be removed from previous room. Basically, a user can be inside one chat room at a time.
• 6. showchatroom: This will show how many chat rooms are currently available which has at least one member. If there is no member in a chat room, that room will be deleted.

• 7. showuser: Show all currently logged in user.

• 8. showfriend: It will show the user’s friend list.

• 9. showrequest: This will show pending friend request. 
• 10. connect: Send a friend request to a user. If user doesn’t exist in the database, then it will show incorrect user.

** Also case like: sending friend request to own self, sending request to user that already been sent etc are also handled, Try typing command like these to check. 

Ok, now if Sifat logs in, then he will automatically see pending requests from different users.

• 11. yes & no: If Sifat type yes aladin, then he and aladin will become friend. If types no aladin, then aladin’s request will be rejected and aladin will be notified via a message. If aladin is not online, then the message will be pending, else aladin will receive rejection instantly.

• 12. message: Type message aladin to send aladin a private message.

As aladin doesn’t have friend named Sifat, so private message won’t be possible. So let’s make friends:

Now, both of them can share private message. Suppose, aladin sent a message to Sifat. If Sifat is online, he will receive the message. If Sifat is offline, the message will be stored as pending message. When Sifat will log in, he will then receive all the pending messages from different users.

**If user is not in any chat room, all of his messages will be global, an everyone who are logged in globally will receive that message(Broadcast). Private message between friends is Unicast and inside chat room, messages will be counted as multicast (only user in the chat room will receive messages).

You can find my project here: https://github.com/sifatshishir/Client-Server-Multichat

Java MySQL DELETE (using Statement)

See also: MySQL XAMPP Connection for Java jdbc Program

Suppose we have folowing table:



Now we want to delete one record at a time by following:

• Create a Java Connection to our MySQL database.
• Create a SQL DELETE statement.
• Then execute a Java Statement, using our SQL DELETE statement.
• Close our Java MySQL database connection.
• Finally catch any SQL exceptions using try-catch clause.

See also:

• Java MySQL SELECT (using Statement)
• Java MySQL INSERT (using Statement)

Reference

Java MySQL INSERT (using Statement)

See also: MySQL XAMPP Connection for Java jdbc Program

First suppose we have a table in out database named user. Or we can create a simple table like below:



Now we want to insert one record in this table. By following some steps we will do that.

• Create a Java Connection to our MySQL database.
• Create a SQL INSERT statement.
• Then execute a Java Statement, using our SQL INSERT statement.
• Close our Java MySQL database connection.
• Finally catch any SQL exceptions using try-catch clause.

quey1 is passing direct values to the table. query2 is passing values through variables. Be careful about quote marks for executing queries.

See also:

• Java MySQL SELECT (using Statement)
• Java MySQL DELETE (using Statement)

Reference

Java MySQL SELECT (using Statement)

See also: MySQL XAMPP Connection for Java jdbc Program

Let's see the following table:



Now follow these steps:

• Create a Java Connection to our MySQL database.
• Define SQL SELECT statement.
• Then execute the SELECT query, getting a Java ResultSet from that query
• Now iterate over the ResultSet, getting the database fields (columns) from each row of data that is returned
• Close our Java MySQL database connection.
• Finally catch any SQL exceptions using try-catch clause.
  

See also:

• Java MySQL INSERT (using Statement)
• Java MySQL DELETE (using Statement)

Reference

MySQL XAMPP Connection for Java jdbc Program

First we will open our XAMPP server.

Then type localhost/phpmyadmin/ in the browser. After that we will create our database. After that, see below java code for setting up connection for the database.

Java Database Connectivity (JDBC) is an application programming interface (API) for the programming language Java, which defines how a client may access a database. It is Java based data access technology and used for Java database connectivity. It is part of the Java Standard Edition platform, from Oracle Corporation.




"jdbc:mysql://localhost:3306/newdatabase" ; here 3306 is the port number for XAMPP server and newdatabase is the name of our database.

Remember : First create the database, otherwise it won't connect simply by coding
These parts seem ok, but you will get error if you didn't add the appropriate library(ies) to the project using Netbeans's library facility. So, let's see how we can do that :

• First Right-click on the project's root node in the Projects tab.
• In the pop-up context menu, click on Properties (on the bottom of the menu).
• Click on Libraries under Categories:. You should see the following screen:
  
  
  
  
  
  
  
• Click on the Add Library...
• Under Global Libraries click on MySQL JDBC Driver and then click the Add Library button. (If you don't have library named MySQL JDBC Driver, then simply download it from internet)
• Finally Click on OK.
  

If you need a specific version of the driver, you can download it, and then after clicking on Add Library... you can click on Create... to add the downloaded version to your library repository. You'd then remove the default JDBC Driver from the project, and add the library containing the specific version.
Following these steps properly will be enough for you to access your database.
See also:

• Java MySQL INSERT (using Statement)
• Java MySQL DELETE (using Statement)
• Java MySQL SELECT (using Statement)

 Reference