Java IO.pdf - Nguyen Dang Binh

Java I/O
That's pretty much all there is, except for a few methods dealing with socket options and some
other details. In particular, there aren't methods for getting input and output streams. Instead,
accept()returns a Socket object: you call the Socket's getInputStream() or
getOutputStream() method. For example:
try {
ServerSocket ss = new ServerSocket(2345);
Socket s = ss.accept();
OutputStream out = s.getOutputStream();
// Send data to the client.
s.close();
}
catch (IOException e) {System.err.println(e);}
Notice in this example, I closed the Socket s, not the ServerSocket ss. ss is still bound to
port 2345. You get a new socket for each connection and reuse the server socket. For
example, the next code fragment repeatedly accepts connections:
try {
ServerSocket ss = new ServerSocket(2345);
while (true) {
Socket s = ss.accept();
OutputStream out = s.getOutputStream();
// send data to the client
s.close();
}
}
catch (IOException e) {System.err.println(e);}
The program in Example 5.5 reads a port number from the command line. It listens on that
port for incoming connections. When it detects one, it answers back with the client's address
and port and its own. Then it closes the connection.
Example 5.5. The HelloServer Program
import java.net.*;
import java.io.*;
public class HelloServer {
public final static int defaultPort = 2345;
public static void main(String[] args) {
int port = defaultPort;
try {
port = Integer.parseInt(args[0]);
}
catch (Exception e) {}
if (port = 65536) port = defaultPort;
try {
ServerSocket ss = new ServerSocket(port);
while (true) {
try {
Socket s = ss.accept();
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