Java Chat Program

Package Cn.apr.chart;

Import java.net.*;
Import java.io.*;
Import java.util.*;

public class Chatserver {
/**
* @param args
* M_threads is a vector static variable that maintains all server-side Serverthread objects,
* This variable can be Chatapplet broadcast information to all the chat participants who have joined the chat room and revoke the exiting chat.
* The Main method of Chatserver the chat Service person. This method listens for the Chat applet's request and creates a service thread for the newly connected chat user.
*/
public static void Main (string[] args) {
TODO auto-generated Method Stub
ServerSocket socket = NULL;
Vector m_threads = new vector ();
System.out.println ("Listen ...");
try {
Set the ServerSocket listener port number to 5555, which must be the same as the port parameter in the program chat Chatapplet
Socket = new ServerSocket (5555);
} catch (Exception e) {
System.out.println ("New ServerSocket () failed!");
Return
}
try {
int nid = 0;
while (true) {
Monitor if there is a new chat applet attached to the chat server,
The thread runs to the statement that is blocked until a new connection is generated
Socket s = socket.accept ();
SYSTEM.OUT.PRINTLN ("accepted");
Create a new Serverthread
Serverthread st = new Serverthread (s, m_threads);
Set an ID number for the thread
St.setid (nid++);
Adding a thread to the m_threads vector
M_threads.addelement (ST);
Start the service thread
New Thread (ST). Start ();
Notify all Chatapplet have a new netizen to join
for (int i = 0; i < m_threads.size (); i++) {
Serverthread st1 = (serverthread) m_threads.elementat (i);
St1.write ("<#>welcome" + st.getid () + "to enter chatroom!");
}
System.out.println ("Listen again ...");
}
} catch (Exception e) {
System.out.println ("Server is down ...");
}
}
}

Listen to the thread, listen to the corresponding chat applet if there is information coming
Class Serverthread implements Runnable {
Vector m_threads;
Socket m_socket = null;
DataInputStream m_in = null;
DataOutputStream m_out = null;
int M_nid;

Initializing threads
Public Serverthread (Socket s, Vector threads) {
M_socket = s;
M_threads = threads;
try {
Constructing data input and output stream objects
m_in = new DataInputStream (M_socket.getinputstream ());
M_out = new DataOutputStream (M_socket.getoutputstream ());
} catch (Exception e) {
}
}

public void Run ()//thread's execution body
{
SYSTEM.OUT.PRINTLN ("Thread is running");
try {
while (true) {
Listen to the corresponding Chatapplet whether the message came
Thread is blocked in M_in.readutf () until a message comes back
String s = M_in.readutf ();
if (s = = null)
Break
If the message from the chat applet is "Leave", notify all other Chatapplet to launch their own
if (S.trim (). Equals ("Leave"))
for (int i = 0; i < m_threads.size (); i++) {
Serverthread st = (serverthread) m_threads.elementat (i);
St.write ("* * *" + GetID () + "Leave ..." + "* * *");
}
Else
Broadcast the message to all Chatapplet
for (int i = 0; i < m_threads.size (); i++) {
Serverthread st = (serverthread) m_threads.elementat (i);
St.write ("<" + GetID () + ">" + s);
}
}//while (true)
} catch (Exception e) {
E.printstacktrace ();
}
Remove the thread from the M_threads vector, indicating that the thread has left the chat room
M_threads.removeelement (this);
System.out.println ("Remove element!");
try {
M_socket.close ();
} catch (Exception e) {
}
}

Send msg back to the corresponding applet
public void Write (String msg) {
Synchronized (msg) {
try {
M_out.writeutf (msg);
} catch (IOException e) {
}
}
}

public int GetID ()//Get the ID of the thread
{
return M_nid;
}

public void SetID (int nid)//Set the ID of the thread
{
M_nid = nid;
}
}

//////////////

Package Cn.apr.chart;

Import java.awt.*;
Import java.applet.*;
Import java.io.*;
Import java.net.*;

Inherit applets, implement Runnable
public class ChatApplet1 extends Applet implements Runnable {
TextArea M_textarea; Accept Message Display window
TextField M_textfield; Send Message Input window
DataInputStream m_in; Message input stream
DataOutputStream M_out; Message output stream

/**
* @param args
* Initialization method of Chatapplet
*/
public void init () {
Create window
SetLayout (NULL);
SetSize (426, 266);
M_textarea = new TextArea (10, 10);
M_textfield = new TextField ();
m_in = null;
M_out = null;
Initialize the Appleton and connect to the Chat Service person
try {
Gets the URL of the applet, which is the server address
URL url = getcodebase ();
Get Server IP Address
InetAddress inetaddr = Inetaddress.getbyname (Url.gethost ());
Socket M_socket;
The screen displays the server IP address, the communication protocol
System.out.println ("Server:" + inetaddr + "" + url.gethost () + ""
+ Url.getprotocol ());
Create a socket that is connected to the server IP address, 5555 is the chat server socket interface Port
M_socket = new Socket (inetaddr, 5555);
Establishing an input stream on a socket interface
m_in = new DataInputStream (M_socket.getinputstream ());
Establishing an output stream on a socket interface
M_out = new DataOutputStream (M_socket.getoutputstream ());
} catch (Exception e) {
System.out.println ("Error:" + e);
}
SetLayout (New BorderLayout ());
Add ("Center", M_textarea);
Add ("South", M_textfield);
M_textarea.seteditable (FALSE);
Start the listener thread
New Thread (This). Start ();
}

When the chat type enters enter in the message input window, the string is read and sent to the Chat Service person.

public boolean Handleevent (event event) {
String B = M_textfield.gettext ();
if ((Event.target = = M_textfield) && (event.id = = event.action_event)) {
M_textfield.settext ("");
Send the message that the chat person entered to Chatserver
try {
M_out.writeutf (b); Send a uft format string to a chat service person
} catch (IOException e) {
}
return true;
} else
Return Super.handleevent (event);
}

The chat listener listens to the corresponding service thread, reads the message corresponding to the service line Cheng, and displays it in the Communication display window.

public void Run () {
try {
while (true) {
The chat listener listens for messages sent from the corresponding service thread, and it is blocked in the statement until the message arrives
String s = M_in.readutf (); Read a UTF format string
if (s! = null)
Display messages in the Information display window
M_textarea.append (s + "\ n");
}
} catch (Exception e) {
M_textarea.append ("Network problem or Server down.\n");
M_textfield.setvisible (FALSE);
}
}

public void Stop () {
try {
M_out.writeutf ("Leave");
} catch (IOException e) {
}
}

public static void Main (string[] args) {
TODO automatically generate method stubs
}
}

Java Chat Program