mangotiger.bus.BusImpl.java Source code

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Here is the source code for mangotiger.bus.BusImpl.java

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/*
 * $Source: $
 *
 * Copyright (C) 2002-2005, Thomas Robert Gagnier, Jr., All Rights Reserved.
 * Unauthorized use, disclosure or reproduction of this source code is strictly
 * prohibited by United States copyright law and international treaty provisions.
 * Use of source code requires an appropriate source license.
 */
package mangotiger.bus;

import mangotiger.lang.Strings;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/** @author Tom Gagnier */
public class BusImpl implements Bus {
    private final String prefix;
    private final Map<String, Consumer> consumersByEventName = new TreeMap<String, Consumer>();
    private final Set<Object> unregistered = new HashSet<Object>();
    private final Pattern eventMethod;
    private boolean debug;

    public BusImpl() {
        this("on");
    }

    /** @param prefix the required method prefix used by the publisher */
    public BusImpl(final String prefix) {
        this.prefix = prefix;
        final String regex = "public void ([a-zA-Z][a-zA-Z_$]+\\.)+" + prefix + "([A-Z][a-zA-Z0-9]+)\\("
                + Event.class.getName() + "\\)";
        eventMethod = Pattern.compile(regex);
    }

    public BusImpl(final boolean debug) {
        this();
        this.debug = debug;
    }

    public void register(final Object consumer) {
        final Class clazz = consumer.getClass();
        for (Method method : clazz.getMethods()) {
            final Matcher matcher = eventMethod.matcher(method.toString());
            final boolean isEventMethod = matcher.matches();
            if (isEventMethod) {
                final String eventName = Strings.decapitalize(matcher.group(2));
                register(consumer, eventName);
            }
        }
    }

    public void register(final Object consumer, final String eventName) {
        if (!consumersByEventName.containsKey(eventName))
            consumersByEventName.put(eventName, new Consumer());
        consumersByEventName.get(eventName).add(eventName, consumer);
    }

    public void unregister(final Object consumer) {
        unregistered.add(consumer);
    }

    public void publish(final Event event) {
        removeUnregistered();
        final Consumer consumer = consumersByEventName.get(event.name());
        if (consumer == null) {
            if (debug) {
                //noinspection UseOfSystemOutOrSystemErr
                System.err.println(event);
            }
        } else {
            if (debug) {
                //noinspection UseOfSystemOutOrSystemErr
                System.out.println(event);
            }
            consumer.publish(event);
        }
    }

    private void removeUnregistered() {
        if (unregistered.size() == 0)
            return;
        for (Consumer c : consumersByEventName.values()) {
            for (Iterator<WeakReference<Object>> iterator = c.consumerRefs.iterator(); iterator.hasNext();) {
                if (unregistered.contains(iterator.next().get()))
                    iterator.remove();
            }
        }
        unregistered.clear();
    }

    @Override
    public String toString() {
        return "BusImpl{prefix='" + prefix + '\'' + ",consumersByEventName=" + consumersByEventName
                + ",unregistered=" + unregistered + ",eventMethod=" + eventMethod + '}';
    }

    private class Consumer {
        private final List<WeakReference<Object>> consumerRefs = new ArrayList<WeakReference<Object>>();
        private final Map<String, Method> methodsByClassName = new TreeMap<String, Method>();

        private void add(final String event, final Object consumer) {
            try {
                consumerRefs.add(new WeakReference<Object>(consumer));
                final Class clazz = consumer.getClass();
                final String classname = clazz.getName();
                if (methodsByClassName.containsKey(classname))
                    return;
                final StringBuilder name = new StringBuilder(prefix.length() + event.length()).append(prefix)
                        .append(event);
                name.setCharAt(prefix.length(), Character.toUpperCase(event.charAt(0)));
                final Method method = consumer.getClass().getMethod(name.toString(), Event.class);
                methodsByClassName.put(classname, method);
            } catch (NoSuchMethodException e) {
                throw new IllegalStateException(e);
            }
        }

        private void publish(final Event event) {
            log().debug(event);
            for (WeakReference<Object> consumerRef : consumerRefs) {
                final String classname = consumerRef.get().getClass().getName();
                final Method method = methodsByClassName.get(classname);
                final Object consumer = consumerRef.get();
                try {
                    method.invoke(consumer, event);
                } catch (IllegalAccessException e) {
                    log().error(new StringBuilder().append("unable to access ").append(method).toString(), e);
                } catch (InvocationTargetException e) {
                    log().error(new StringBuilder().append("unable to invoke ").append(method).toString(), e);
                }
            }
        }

        @Override
        public String toString() {
            return "Consumer{consumerRefs=" + consumerRefs + ",methodsByClassName=" + methodsByClassName + '}';
        }

        private Log log() {
            return LogFactory.getLog(Consumer.class);
        }
    }
}