org.osgi.service.event.Event Maven / Gradle / Ivy
/*
* Copyright (c) OSGi Alliance (2005, 2009). All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.osgi.service.event;
import java.util.Collections;
import java.util.Dictionary;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.osgi.framework.Filter;
/**
* An event.
*
* Event objects are delivered to EventHandler
* services which subscribe to the topic of the event.
*
* @Immutable
* @version $Revision: 7003 $
*/
public class Event {
/**
* The topic of this event.
*/
private final String topic;
/**
* The properties carried by this event. Keys are strings and values are
* objects
*/
private final Map /* */properties;
/**
* Constructs an event.
*
* @param topic The topic of the event.
* @param properties The event's properties (may be null). A
* property whose key is not of type String will be
* ignored.
* @throws IllegalArgumentException If topic is not a valid topic name.
* @since 1.2
*/
public Event(String topic, Map/* */properties) {
validateTopicName(topic);
this.topic = topic;
int size = (properties == null) ? 1 : (properties.size() + 1);
Map p = new HashMap(size);
if (properties != null) {
for (Iterator iter = properties.keySet().iterator(); iter.hasNext();) {
Object key = iter.next();
if (key instanceof String) {
Object value = properties.get(key);
p.put(key, value);
}
}
}
p.put(EventConstants.EVENT_TOPIC, topic);
this.properties = p; // safely publish the map
}
/**
* Constructs an event.
*
* @param topic The topic of the event.
* @param properties The event's properties (may be null). A
* property whose key is not of type String will be
* ignored.
* @throws IllegalArgumentException If topic is not a valid topic name.
*/
public Event(String topic, Dictionary/* */properties) {
validateTopicName(topic);
this.topic = topic;
int size = (properties == null) ? 1 : (properties.size() + 1);
Map p = new HashMap(size);
if (properties != null) {
for (Enumeration e = properties.keys(); e.hasMoreElements();) {
Object key = e.nextElement();
if (key instanceof String) {
Object value = properties.get(key);
p.put(key, value);
}
}
}
p.put(EventConstants.EVENT_TOPIC, topic);
this.properties = p; // safely publish the map
}
/**
* Retrieves a property.
*
* @param name the name of the property to retrieve
* @return The value of the property, or null if not found.
*/
public final Object getProperty(String name) {
return properties.get(name);
}
/**
* Returns a list of this event's property names.
*
* @return A non-empty array with one element per property.
*/
public final String[] getPropertyNames() {
return (String[]) properties.keySet().toArray(
new String[properties.size()]);
}
/**
* Returns the topic of this event.
*
* @return The topic of this event.
*/
public final String getTopic() {
return topic;
}
/**
* Tests this event's properties against the given filter using a case
* sensitive match.
*
* @param filter The filter to test.
* @return true If this event's properties match the filter, false
* otherwise.
*/
public final boolean matches(Filter filter) {
return filter.matchCase(new UnmodifiableDictionary(properties));
}
/**
* Compares this Event object to another object.
*
*
* An event is considered to be equal to another event if the topic
* is equal and the properties are equal.
*
* @param object The Event object to be compared.
* @return true if object is a Event
* and is equal to this object; false otherwise.
*/
public boolean equals(Object object) {
if (object == this) { // quick test
return true;
}
if (!(object instanceof Event)) {
return false;
}
Event event = (Event) object;
return topic.equals(event.topic) && properties.equals(event.properties);
}
/**
* Returns a hash code value for the object.
*
* @return An integer which is a hash code value for this object.
*/
public int hashCode() {
int h = 31 * 17 + topic.hashCode();
h = 31 * h + properties.hashCode();
return h;
}
/**
* Returns the string representation of this event.
*
* @return The string representation of this event.
*/
public String toString() {
return getClass().getName() + " [topic=" + topic + "]";
}
/**
* Called by the constructor to validate the topic name.
*
* @param topic The topic name to validate.
* @throws IllegalArgumentException If the topic name is invalid.
*/
private static void validateTopicName(String topic) {
char[] chars = topic.toCharArray();
int length = chars.length;
if (length == 0) {
throw new IllegalArgumentException("empty topic");
}
for (int i = 0; i < length; i++) {
char ch = chars[i];
if (ch == '/') {
// Can't start or end with a '/' but anywhere else is okay
if (i == 0 || (i == length - 1)) {
throw new IllegalArgumentException(
"invalid topic: "
+ topic);
}
// Can't have "//" as that implies empty token
if (chars[i-1] == '/') {
throw new IllegalArgumentException(
"invalid topic: "
+ topic);
}
continue;
}
if (('A' <= ch) && (ch <= 'Z')) {
continue;
}
if (('a' <= ch) && (ch <= 'z')) {
continue;
}
if (('0' <= ch) && (ch <= '9')) {
continue;
}
if ((ch == '_') || (ch == '-')) {
continue;
}
throw new IllegalArgumentException("invalid topic: " + topic);
}
}
/**
* Unmodifiable wrapper for Dictionary.
*/
private static class UnmodifiableDictionary extends Dictionary {
private final Map wrapped;
UnmodifiableDictionary(Map wrapped) {
this.wrapped = wrapped;
}
public Enumeration elements() {
return Collections.enumeration(wrapped.values());
}
public Object get(Object key) {
return wrapped.get(key);
}
public boolean isEmpty() {
return wrapped.isEmpty();
}
public Enumeration keys() {
return Collections.enumeration(wrapped.keySet());
}
public Object put(Object key, Object value) {
throw new UnsupportedOperationException();
}
public Object remove(Object key) {
throw new UnsupportedOperationException();
}
public int size() {
return wrapped.size();
}
}
}