Java Server Error Examples
Getting these errors in some java code
http://tutorials.jenkov.com/java-multithreaded-servers/multithreaded-server.html
Exception in thread "Thread-0" java.lang.RuntimeException: Cannot open port 8080
at servers.MultiThreadedServer.openServerSocket(MultiThreadedServer.java:61)
at servers.MultiThreadedServer.run(MultiThreadedServer.java:22)
at java.lang.Thread.run(Thread.java:679)
Caused by: java.net.BindException: Address already in use
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:353)
at java.net.ServerSocket.bind(ServerSocket.java:336)
at java.net.ServerSocket.<init>(ServerSocket.java:202)
at java.net.ServerSocket.<init>(ServerSocket.java:114)
at servers.MultiThreadedServer.openServerSocket(MultiThreadedServer.java:59)
... 2 more
Exception in thread "main" Stopping Server
java.lang.NullPointerException
at servers.MultiThreadedServer.stop(MultiThreadedServer.java:51)
at servers.Dispatch.main(Dispatch.java:18)
I made these files
WorkerRunnable.java
package servers;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.net.Socket;
/**
*/
public class WorkerRunnable implements Runnable{
protected Socket clientSocket = null;
protected String serverText = null;
public WorkerRunnable(Socket clientSocket, String serverText) {
this.clientSocket = clientSocket;
this.serverText = serverText;
}
public void run() {
try {
InputStream input = clientSocket.getInputStream();
OutputStream output = clientSocket.getOutputStream();
long time = System.currentTimeMillis();
output.write(("HTTP/1.1 200 OK\n\nWorkerRunnable: " +
this.serverText + " - " +
time +
"").getBytes());
output.close();
input.close();
System.out.println("Request processed: " + time);
} catch (IOException e) {
//report exception somewhere.
e.printStackTrace();
}
}
}
MultiThreadedServer.java
package servers;
import java.net.ServerSocket;
import java.net.Socket;
import java.io.IOException;
public class MultiThreadedServer implements Runnable{
protected int serverPort = 8080;
protected ServerSocket serverSocket = null;
protected boolean isStopped = false;
protected Thread runningThread= null;
public MultiThreadedServer(int port){
this.serverPort = port;
}
public void run(){
synchronized(this){
this.runningThread = Thread.currentThread();
}
openServerSocket();
while(! isStopped()){
Socket clientSocket = null;
try {
clientSocket = this.serverSocket.accept();
} catch (IOException e) {
if(isStopped()) {
System.out.println("Server Stopped.") ;
return;
}
throw new RuntimeException(
"Error accepting client connection", e);
}
new Thread(
new WorkerRunnable(
clientSocket, "Multithreaded Server")
).start();
}
System.out.println("Server Stopped.") ;
}
private synchronized boolean isStopped() {
return this.isStopped;
}
public synchronized void stop(){
this.isStopped = true;
try {
this.serverSocket.close();
} catch (IOException e) {
throw new RuntimeException("Error closing server", e);
}
}
private void openServerSocket() {
try {
this.serverSocket = new ServerSocket(this.serverPort);
} catch (IOException e) {
throw new RuntimeException("Cannot open port 8080", e);
}
}
}
Dispatch.java
package servers;
public class Dispatch {
/**
* @param args
*/
public static void main(String[] args) {
MultiThreadedServer server = new MultiThreadedServer(9000);
new Thread(server).start();
try {
Thread.sleep(20 * 1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Stopping Server");
server.stop();
}
}
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3 answers
Your machine port is being 8080
used by another program
End program using port 8080
You can find out the program with the following command (Windows):
netstat -o -n -a | findstr 0.0:8080
Output example:
TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING 8704
Then you can find the program by PID 8704
using Task Manager and terminate it.
See here for details .
Use a different port
You can change
protected int serverPort = 8080;
to
protected int serverPort = 8888;
or
MultiThreadedServer server = new MultiThreadedServer(8888);
So the 8080
port is used instead 8888
.
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