Question

How can I parse URL queries with a system like this.

For Example something like get these URL arguments in variables.

http://localhost?format=json&apikey=838439873473kjdhfkhdf

http://tutorials.jenkov.com/java-multithreaded-servers/multithreaded-server.html

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();

}

}

Answer 1

You’re doing fine so far.

Read the data off of the InputStream (BufferedReader might help) one line at a time.
Read and learn the HTTP Protocol (see Request Message section here: http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol).

The first line that the client sends is going to follow that format: GET /foo.html?x=y&a=b HTTP/1.1 followed by \n\n that’s the Method, URL (with query parameters) and Protocol. Split that line (on the spaces…) and then break the URL up according to the specs.

Everything you need can be found in the String class for parsing the data.