signalmanager.java

java信号处理程序

package kh.signal;


import java.util.*;

/**
   The central clearinghouse for JavaSignals.

   Copyright 1998 Kevin Hester, [e-mail]
   
   Commerical use prohibited - non commercial distribution is OK.
   Contact the author for further information.
*/


public class SignalManager 
    {
	/**
	   Adds a listener which is interested in certain signals.

	   @param listener the instance which would like to be informed on a signal.
	*/
	public static void addListener(SignalListener listener)
	    {
		startManager();

		for(int i = listener.SIG_MIN; i <= listener.SIG_MAX; i++)
			if(listener.isInterested(i))
				interestMask |= (1 << i);

		// System.out.println("JAVA: interest mask: " + interestMask);

		listeners.addElement(listener);
		
		setInterestMask();
		}

	/**
	   Removes a listener.

	   @param listener the listener to remove.
	*/
	public static void removeListener(SignalListener listener)
	    {
		// FIXME - remove things from the interest mask

		listeners.removeElement(listener);
		}

	private static void startManager()
	    {
		if(managerStarted)
			return;

		// Load our native code - I prefer to only load native code once the user
		// has called addListener.

		System.loadLibrary("Signal");

		new SignalManagerThread();
		managerStarted = true;
		}


	/**
	   A query function to provide runtime version checking
	*/
	public static String getVersion()
	    {
		return "Java Signals Version 1.0 - Copyright 1998 Kevin Hester, [e-mail]";
		}


	/**
	   Native code which blocks until a signal is received.
	*/
	static native int waitForSignal();

	/**
	   Native code to inform C land of what signals we are interested in.

	   FIXME - make this synchronized!!!!
	*/
    private static native void setInterestMask();

	static Vector listeners = new Vector();
    private static int interestMask = 0;
    private static boolean managerStarted = false;
    }