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Java example source code file (SimpleServer.java)

This example Java source code file (SimpleServer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bufferedreader, bytesperop, connhandler, exception, inputstream, maxconn, net, network, object, portnum, serversocket, simpleserver, socket, string, thread

The SimpleServer.java Java example source code

/*
 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */


import java.io.*;
import java.net.*;
import java.lang.Byte;

/**
 * Simple Java "server" using a single thread to handle each connection.
 */

public class SimpleServer
{
  private final static int BYTESPEROP= PollingServer.BYTESPEROP;
  private final static int PORTNUM   = PollingServer.PORTNUM;
  private final static int MAXCONN   = PollingServer.MAXCONN;

  /*
   * This synchronization object protects access to certain
   * data (bytesRead,eventsToProcess) by concurrent Consumer threads.
   */
  private final static Object eventSync = new Object();

  private static InputStream[] instr = new InputStream[MAXCONN];
  private static int bytesRead;
  private static int bytesToRead;

  public SimpleServer() {
    Socket[] sockArr = new Socket[MAXCONN];
    long timestart, timestop;
    int bytes;
    int totalConn=0;


    System.out.println ("Serv: Initializing port " + PORTNUM);
    try {

      ServerSocket skMain = new ServerSocket (PORTNUM);

      bytesRead = 0;
      Socket ctrlSock = skMain.accept();

      BufferedReader ctrlReader =
        new BufferedReader(new InputStreamReader(ctrlSock.getInputStream()));
      String ctrlString = ctrlReader.readLine();
      bytesToRead = Integer.valueOf(ctrlString).intValue();
      ctrlString = ctrlReader.readLine();
      totalConn = Integer.valueOf(ctrlString).intValue();

      System.out.println("Receiving " + bytesToRead + " bytes from " +
                         totalConn + " client connections");

      timestart = System.currentTimeMillis();

      /*
       * Take connections, spawn off connection handling threads
       */
      ConnHandler[] connHA = new ConnHandler[MAXCONN];
      int conn = 0;
      while ( conn < totalConn ) {
          Socket sock = skMain.accept();
          connHA[conn] = new ConnHandler(sock.getInputStream());
          connHA[conn].start();
          conn++;
      }

      while ( bytesRead < bytesToRead ) {
          java.lang.Thread.sleep(500);
      }
      timestop = System.currentTimeMillis();
      System.out.println("Time for all reads (" + totalConn +
                         " sockets) : " + (timestop-timestart));
      // Tell the client it can now go away
      byte[] buff = new byte[BYTESPEROP];
      ctrlSock.getOutputStream().write(buff,0,BYTESPEROP);
    } catch (Exception exc) { exc.printStackTrace(); }
  }

  /*
   * main ... just create invoke the SimpleServer constructor.
   */
  public static void main (String args[])
  {
    SimpleServer server = new SimpleServer();
  }

  /*
   * Connection Handler inner class...one of these per client connection.
   */
  class ConnHandler extends Thread {
    private InputStream instr;
    public ConnHandler(InputStream inputStr) { instr = inputStr; }

    public void run() {
      try {
        int bytes;
        byte[] buff = new byte[BYTESPEROP];

        while ( bytesRead < bytesToRead ) {
          bytes = instr.read (buff, 0, BYTESPEROP);
          if (bytes > 0 ) {
            synchronized(eventSync) {
              bytesRead += bytes;
            }
            /*
             * Any real server would do some synchronized and some
             * unsynchronized work on behalf of the client, and
             * most likely send some data back...but this is a
             * gross oversimplification.
             */
          }
          else {
            if (bytesRead < bytesToRead)
              System.out.println("instr.read returned : " + bytes);
          }
        }
      }
      catch (Exception e) {e.printStackTrace();}
    }
  }
}

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