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建立时间:2006年5月29日 |
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 [J2SE]A multi-threaded socket-based server
软件技术
lhwork 发表于 2006/8/7 10:14:01 |
| The problem is old - How to implement a multi-threaded, socket-based server
that will let you read and write to the client (for example a telnet terminal.
There are several problems with constructing such a server:
You have to use threads because otherwise clients will be queued up
waiting for a connection.Many of the publically available examples (even some in some books)
do not work for I/O servers. They are mostly developed around reading from
a socket not writing to the socket as well. In our example we give a working
read/write code example.You need to avoid race conditions when starting up a thread at times
when connections are coming through thick and fast.
The code below will implement just such a server. It is intended for a head
start, so is a template rather than a tutorial on how to write a server in
Java. We have decided on port 4444 to listen on in the example, but you need
to decide on a suitable port yourself.
The server will run, establishing connections from the port and echoing input
received until it receives a line of input that is a full stop only ".".
Have fun!
The Kieser.net team.
package sample_server;
import java.io.*;
import java.net.*;
import java.security.*;
/**
* Title: Sample Server
* Description: This utility will accept input from a socket,
posting back to the socket before closing the link.
* It is intended as a template for coders to base servers on. Please
report bugs to brad at kieser.net
* Copyright: Copyright (c) 2002
* Company: Kieser.net
* @author B. Kieser
* @version 1.0
*/
public class sample_server {
private static int port=4444, maxConnections=0;
// Listen for incoming connections and handle them
public static void main(String[] args) {
int i=0;
try{
ServerSocket listener = new ServerSocket(port);
Socket server;
while((i++ < maxConnections) || (maxConnections
== 0)){
doComms connection;
server = listener.accept();
doComms conn_c= new doComms(server);
Thread t = new Thread(conn_c);
t.start();
}
} catch (IOException ioe) {
System.out.println("IOException on socket
listen: " + ioe);
ioe.printStackTrace();
}
}
}
class doComms implements Runnable {
private Socket server;
private String line,input;
doComms(Socket server) {
this.server=server;
}
public void run () {
input="";
try {
// Get input from the client
DataInputStream in = new DataInputStream
(server.getInputStream());
PrintStream out = new PrintStream(server.getOutputStream());
while((line = in.readLine()) !=
null && !line.equals(".")) {
input=input + line;
out.println("I got:"
+ line);
}
// Now write to the client
System.out.println("Overall message
is:" + input);
out.println("Overall message is:"
+ input);
server.close();
} catch (IOException ioe) {
System.out.println("IOException
on socket listen: " + ioe);
ioe.printStackTrace();
}
}
}
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