server2.java

C-S模式下提供主机间相互通信的功能

import java.io.*; 
import java.net.*; 
import java.awt.*; 
import java.awt.event.*; 

// Java extension packages 
import javax.swing.*; 

public class Server2 extends JFrame { 
private JTextField enterField; 
private JTextArea displayArea; 
private ObjectOutputStream output; 
private ObjectInputStream input; 
private ServerSocket server; 
private Socket connection; 
private int counter = 1; 

// set up GUI 
public Server2() 
{ 
super( "Server" ); 

Container container = getContentPane(); 

// create enterField and register listener 
enterField = new JTextField(); 
enterField.setEnabled( false ); 

enterField.addActionListener( 

new ActionListener() { 

// send message to client 
public void actionPerformed( ActionEvent event ) 
{ 
sendData( event.getActionCommand() ); 

} 

} // end anonymous inner class 

); // end call to addActionListener 

container.add( enterField, BorderLayout.NORTH ); 

// create displayArea 
displayArea = new JTextArea(); 
container.add( new JScrollPane( displayArea ), 
BorderLayout.CENTER ); 

setSize( 300, 150 ); 
setVisible( true ); 
} 

// set up and run server 
public void runServer() 
{ 
// set up server to receive connections; 
// process connections 
try { 

// Step 1: Create a ServerSocket. 
server = new ServerSocket( 5000, 100 ); //ServerSocket(int port, int backlog) 
                                        //利用指定的 backlog 创建服务器套接字并将其绑定到指定的本地端口号。

while ( true ) { 

// Step 2: Wait for a connection. 
waitForConnection(); 

// Step 3: Get input and output streams. 
getStreams(); 

// Step 4: Process connection. 
processConnection(); 

// Step 5: Close connection. 
closeConnection(); 

++counter; 
} 
} 

// process EOFException when client closes connection 
catch ( EOFException eofException ) { 
System.out.println( "Client terminated connection" ); 
} 

// process problems with I/O 
catch ( IOException ioException ) { 
ioException.printStackTrace(); 
} 
} 

// wait for connection to arrive, then display connection info 
private void waitForConnection() throws IOException 
{ 
displayArea.setText( "Waiting for connection\n" ); 

// allow server to accept a connection 
connection = server.accept(); 

displayArea.append( "Connection " + counter + 
" received from: " + 
connection.getInetAddress().getHostName() ); 
} 

// get streams to send and receive data 
private void getStreams() throws IOException 
{ 
// set up output stream for objects 
output = new ObjectOutputStream( 
connection.getOutputStream() ); 

// flush output buffer to send header information 
output.flush(); 

// set up input stream for objects 
input = new ObjectInputStream( 
connection.getInputStream() ); 

displayArea.append( "\nGot I/O streams\n" ); 
} 

// process connection with client 
private void processConnection() throws IOException 
{ 
// send connection successful message to client 
String message = "SERVER>>> Connection successful"; 
output.writeObject( message ); 
output.flush(); 

// enable enterField so server user can send messages 
enterField.setEnabled( true ); 

// process messages sent from client 
do { 

// read message and display it 
try { 
message = ( String ) input.readObject(); 

displayArea.append( "\n" + message ); 
displayArea.setCaretPosition( 
displayArea.getText().length() ); 
} 

// catch problems reading from client 
catch ( ClassNotFoundException classNotFoundException ) { 
displayArea.append( "\nUnknown object type received" ); 
} 

} while ( !message.equals( "CLIENT>>> TERMINATE" ) ); 
} 

// close streams and socket 
private void closeConnection() throws IOException 
{ 
displayArea.append( "\nUser terminated connection" ); 
enterField.setEnabled( false ); 
output.close(); 
input.close(); 
connection.close(); 
} 

// send message to client 
private void sendData( String message ) 
{ 
// send object to client 
try { 
output.writeObject( "SERVER>>> " + message ); 
output.flush(); 
displayArea.append( "\nSERVER>>>" + message ); 
} 

// process problems sending object 
catch ( IOException ioException ) { 
displayArea.append( "\nError writing object" ); 
} 
} 

// execute application 
public static void main( String args[] ) 
{ 
Server2 application = new Server2(); 

application.setDefaultCloseOperation( 
JFrame.EXIT_ON_CLOSE ); 

application.runServer(); 
} 

}