Read from a Serial port, notifying when data arrives : COM Port « Development Class « Java






Read from a Serial port, notifying when data arrives

 
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.TooManyListenersException;

import javax.comm.CommPort;
import javax.comm.CommPortIdentifier;
import javax.comm.NoSuchPortException;
import javax.comm.ParallelPort;
import javax.comm.PortInUseException;
import javax.comm.SerialPort;
import javax.comm.SerialPortEvent;
import javax.comm.SerialPortEventListener;
import javax.comm.UnsupportedCommOperationException;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/**
 * Read from a Serial port, notifying when data arrives.
 * Simulation of part of an event-logging service.
 * @version $Id: SerialReadByEvents.java,v 1.4 2004/04/11 23:50:40 ian Exp $
 * @author  Ian F. Darwin, http://www.darwinsys.com/
 */
public class SerialReadByEvents extends CommPortOpen 
  implements SerialPortEventListener {

  public static void main(String[] argv)
    throws IOException, NoSuchPortException, PortInUseException,
      UnsupportedCommOperationException {

    new SerialReadByEvents(null).converse();
  }

  /* Constructor */
  public SerialReadByEvents(JFrame f)
    throws IOException, NoSuchPortException, PortInUseException,
      UnsupportedCommOperationException {
    
    super(f);
  }

  /** 
   * Hold the conversation. 
   */
  protected void converse() throws IOException {

    if (!(thePort instanceof SerialPort)) {
      System.err.println("But I wanted a SERIAL port!");
      System.exit(1);
    }
    // Tell the Comm API that we want serial events.
    ((SerialPort)thePort).notifyOnDataAvailable(true);
    try {
      ((SerialPort)thePort).addEventListener(this);
    } catch (TooManyListenersException ev) {
      // "CantHappen" error
      System.err.println("Too many listeners(!) " + ev);
      System.exit(0);
    }
  
    
  }
  public void serialEvent(SerialPortEvent ev) {
    String line;
    try {
      line = is.readLine();
      if (line == null) {
        System.out.println("EOF on serial port.");
        System.exit(0);
      }
      os.println(line);
    } catch (IOException ex) {
      System.err.println("IO Error " + ex);
    }
  }
}


/**
 * Open a serial port using Java Communications.
 *
 * @author  Ian F. Darwin, http://www.darwinsys.com/
 */
class CommPortOpen {
  /** How long to wait for the open to finish up. */
  public static final int TIMEOUTSECONDS = 30;
  /** The baud rate to use. */
  public static final int BAUD = 19200;
  /** The parent JFrame, for the chooser. */
  protected JFrame parent;
  /** The input stream */
  protected BufferedReader is;
  /** The output stream */
  protected PrintStream os;
  /** The chosen Port Identifier */
  CommPortIdentifier thePortID;
  /** The chosen Port itself */
  CommPort thePort;

  public static void main(String[] argv)
    throws IOException, NoSuchPortException, PortInUseException,
      UnsupportedCommOperationException {

    new CommPortOpen(null).converse();

    System.exit(0);
  }

  /* Constructor */
  public CommPortOpen(JFrame f)
    throws IOException, NoSuchPortException, PortInUseException,
      UnsupportedCommOperationException {
    
    // Use the PortChooser from before. Pop up the JDialog.
    PortChooser chooser = new PortChooser(null);

    String portName = null;
    do {
      chooser.setVisible(true);
      
      // Dialog done. Get the port name.
      portName = chooser.getSelectedName();

      if (portName == null)
        System.out.println("No port selected. Try again.\n");
    } while (portName == null);

    // Get the CommPortIdentifier.
    thePortID = chooser.getSelectedIdentifier();

    // Now actually open the port.
    // This form of openPort takes an Application Name and a timeout.
    // 
    System.out.println("Trying to open " + thePortID.getName() + "...");

    switch (thePortID.getPortType()) {
    case CommPortIdentifier.PORT_SERIAL:
      thePort = thePortID.open("DarwinSys DataComm",
        TIMEOUTSECONDS * 1000);
      SerialPort myPort = (SerialPort) thePort;

      // set up the serial port
      myPort.setSerialPortParams(BAUD, SerialPort.DATABITS_8,
        SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
      break;

    case CommPortIdentifier.PORT_PARALLEL:
      thePort = thePortID.open("DarwinSys Printing",
        TIMEOUTSECONDS * 1000);
      ParallelPort pPort = (ParallelPort)thePort;

      // Tell API to pick "best available mode" - can fail!
      // myPort.setMode(ParallelPort.LPT_MODE_ANY);

      // Print what the mode is
      int mode = pPort.getMode();
      switch (mode) {
        case ParallelPort.LPT_MODE_ECP:
          System.out.println("Mode is: ECP");
          break;
        case ParallelPort.LPT_MODE_EPP:
          System.out.println("Mode is: EPP");
          break;
        case ParallelPort.LPT_MODE_NIBBLE:
          System.out.println("Mode is: Nibble Mode.");
          break;
        case ParallelPort.LPT_MODE_PS2:
          System.out.println("Mode is: Byte mode.");
          break;
        case ParallelPort.LPT_MODE_SPP:
          System.out.println("Mode is: Compatibility mode.");
          break;
        // ParallelPort.LPT_MODE_ANY is a "set only" mode;
        // tells the API to pick "best mode"; will report the
        // actual mode it selected.
        default:
          throw new IllegalStateException("Parallel mode " + 
            mode + " invalid.");
      }
      break;
    default:  // Neither parallel nor serial??
      throw new IllegalStateException("Unknown port type " + thePortID);
    }

    // Get the input and output streams
    // Printers can be write-only
    try {
      is = new BufferedReader(new InputStreamReader(thePort.getInputStream()));
    } catch (IOException e) {
      System.err.println("Can't open input stream: write-only");
      is = null;
    }
    os = new PrintStream(thePort.getOutputStream(), true);
  }

  /** This method will be overridden by non-trivial subclasses
   * to hold a conversation. 
   */
  protected void converse() throws IOException {

    System.out.println("Ready to read and write port.");

    // Input/Output code not written -- must subclass.

    // Finally, clean up.
    if (is != null)
      is.close();
    os.close();
  }
}
class PortChooser extends JDialog implements ItemListener {
  /** A mapping from names to CommPortIdentifiers. */
  protected HashMap map = new HashMap();
  /** The name of the choice the user made. */
  protected String selectedPortName;
  /** The CommPortIdentifier the user chose. */
  protected CommPortIdentifier selectedPortIdentifier;
  /** The JComboBox for serial ports */
  protected JComboBox serialPortsChoice;
  /** The JComboBox for parallel ports */
  protected JComboBox parallelPortsChoice;
  /** The JComboBox for anything else */
  protected JComboBox other;
  /** The SerialPort object */
  protected SerialPort ttya;
  /** To display the chosen */
  protected JLabel choice;
  /** Padding in the GUI */
  protected final int PAD = 5;

  /** This will be called from either of the JComboBoxen when the
   * user selects any given item.
   */
  public void itemStateChanged(ItemEvent e) {
    // Get the name
    selectedPortName = (String)((JComboBox)e.getSource()).getSelectedItem();
    // Get the given CommPortIdentifier
    selectedPortIdentifier = (CommPortIdentifier)map.get(selectedPortName);
    // Display the name.
    choice.setText(selectedPortName);
  }

  /* The public "getter" to retrieve the chosen port by name. */
  public String getSelectedName() {
    return selectedPortName;
  }

  /* The public "getter" to retrieve the selection by CommPortIdentifier. */
  public CommPortIdentifier getSelectedIdentifier() {
    return selectedPortIdentifier;
  }

  /** A test program to show up this chooser. */
  public static void main(String[] ap) {
    PortChooser c = new PortChooser(null);
    c.setVisible(true);  // blocking wait
    System.out.println("You chose " + c.getSelectedName() +
      " (known by " + c.getSelectedIdentifier() + ").");
    System.exit(0);
  }

  /** Construct a PortChooser --make the GUI and populate the ComboBoxes.
   */
  public PortChooser(JFrame parent) {
    super(parent, "Port Chooser", true);

    makeGUI();
    populate();
    finishGUI();
  }

  /** Build the GUI. You can ignore this for now if you have not
   * yet worked through the GUI chapter. Your mileage may vary.
   */
  protected void makeGUI() {
    Container cp = getContentPane();

    JPanel centerPanel = new JPanel();
    cp.add(BorderLayout.CENTER, centerPanel);

    centerPanel.setLayout(new GridLayout(0,2, PAD, PAD));

    centerPanel.add(new JLabel("Serial Ports", JLabel.RIGHT));
    serialPortsChoice = new JComboBox();
    centerPanel.add(serialPortsChoice);
    serialPortsChoice.setEnabled(false);

    centerPanel.add(new JLabel("Parallel Ports", JLabel.RIGHT));
    parallelPortsChoice = new JComboBox();
    centerPanel.add(parallelPortsChoice);
    parallelPortsChoice.setEnabled(false);

    centerPanel.add(new JLabel("Unknown Ports", JLabel.RIGHT));
    other = new JComboBox();
    centerPanel.add(other);
    other.setEnabled(false);

    centerPanel.add(new JLabel("Your choice:", JLabel.RIGHT));
    centerPanel.add(choice = new JLabel());

    JButton okButton;
    cp.add(BorderLayout.SOUTH, okButton = new JButton("OK"));
    okButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        PortChooser.this.dispose();
      }
    });

  }

  /** Populate the ComboBoxes by asking the Java Communications API
   * what ports it has.  Since the initial information comes from
   * a Properties file, it may not exactly reflect your hardware.
   */
  protected void populate() {
    // get list of ports available on this particular computer,
    // by calling static method in CommPortIdentifier.
    Enumeration pList = CommPortIdentifier.getPortIdentifiers();

    // Process the list, putting serial and parallel into ComboBoxes
    while (pList.hasMoreElements()) {
      CommPortIdentifier cpi = (CommPortIdentifier)pList.nextElement();
      // System.out.println("Port " + cpi.getName());
      map.put(cpi.getName(), cpi);
      if (cpi.getPortType() == CommPortIdentifier.PORT_SERIAL) {
        serialPortsChoice.setEnabled(true);
        serialPortsChoice.addItem(cpi.getName());
      } else if (cpi.getPortType() == CommPortIdentifier.PORT_PARALLEL) {
        parallelPortsChoice.setEnabled(true);
        parallelPortsChoice.addItem(cpi.getName());
      } else {
        other.setEnabled(true);
        other.addItem(cpi.getName());
      }
    }
    serialPortsChoice.setSelectedIndex(-1);
    parallelPortsChoice.setSelectedIndex(-1);
  }

  protected void finishGUI() {
    serialPortsChoice.addItemListener(this);
    parallelPortsChoice.addItemListener(this);
    other.addItemListener(this);
    pack();
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}


           
         
  








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