org.jboss.ejb.client.Attachable Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* JBoss, Home of Professional Open Source.
* Copyright 2017 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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.jboss.ejb.client;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Map;
import org.wildfly.common.Assert;
/**
* An object which may have attachments. Even if the object is serializable, its
* attachment map is not and will always deserialize empty.
*
* @author David M. Lloyd
*/
public abstract class Attachable {
private final Map, Object> attachments;
private Attachable(Map, Object> attachments) {
this.attachments = attachments;
}
Attachable() {
this(new IdentityHashMap, Object>());
}
/**
* Construct a new instance, sharing attachments with another instance.
*
* @param attachable the attachments to share
*/
Attachable(final Attachable attachable) {
this(attachable.attachments);
}
/**
* Get an attachment from this object.
*
* @param key the attachment key
* @param the attachment type
* @return the attachment value
*/
@SuppressWarnings("unchecked")
public T getAttachment(AttachmentKey key) {
if (key == null) return null;
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) attachments.get(key);
}
}
/**
* Returns the attachments applicable for this {@link Attachable}. The returned {@link Map}
* is an unmodifiable {@link Map}. If there are no attachments for this {@link Attachable}
* then this method returns an empty {@link Map}
*
* @return a read-only copy of the attachments map
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public Map, ?> getAttachments() {
if (this.attachments == null) {
return Collections.emptyMap();
}
return Collections.unmodifiableMap((Map) this.attachments);
}
/**
* Set an attachment on this object.
*
* @param key the attachment key
* @param value the attachment's new value (may not be {@code null})
* @param the attachment type
* @return the previous attachment value, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T putAttachment(AttachmentKey key, T value) {
Assert.checkNotNullParam("key", key);
Assert.checkNotNullParam("value", value);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) attachments.put(key, value);
}
}
/**
* Set an attachment on this object if an existing attachment does not already exist.
*
* @param key the attachment key
* @param value the attachment's new value (may not be {@code null})
* @param the attachment type
* @return the previous attachment value, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T putAttachmentIfAbsent(AttachmentKey key, T value) {
Assert.checkNotNullParam("key", key);
Assert.checkNotNullParam("value", value);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) (attachments.containsKey(key) ? attachments.get(key) : attachments.put(key, value));
}
}
/**
* Replace an attachment on this object if an existing attachment exists.
*
* @param key the attachment key
* @param value the attachment's new value (may not be {@code null})
* @param the attachment type
* @return the previous attachment value, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T replaceAttachment(AttachmentKey key, T value) {
if (key == null) return null;
Assert.checkNotNullParam("value", value);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) (attachments.containsKey(key) ? attachments.put(key, value) : null);
}
}
/**
* Replace an attachment on this object if an existing attachment exists with a certain value.
*
* @param key the attachment key
* @param oldValue the attachment's expected value (may not be {@code null})
* @param newValue the attachment's new value (may not be {@code null})
* @param the attachment type
* @return {@code true} if the old value matched and the value was replaced; {@code false} otherwise
*/
@SuppressWarnings("unchecked")
public boolean replaceAttachment(AttachmentKey key, T oldValue, T newValue) {
if (key == null) return false;
if (oldValue == null) return false;
Assert.checkNotNullParam("newValue", newValue);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
Object lhs = attachments.get(key);
return attachments.containsKey(key) && oldValue.equals(lhs) && attachments.put(key, newValue) != null;
}
}
/**
* Remove and return an attachment value.
*
* @param key the attachment key
* @param the attachment type
* @return the previous value of the attachment, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T removeAttachment(AttachmentKey key) {
if (key == null) return null;
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) attachments.remove(key);
}
}
/**
* Remove an attachment if it has a certain value.
*
* @param key the attachment key
* @param value the attachment's expected value (may not be {@code null})
* @param the attachment type
* @return {@code true} if the value was removed, {@code false} if there was no attachment
*/
@SuppressWarnings("unchecked")
public boolean removeAttachment(AttachmentKey key, T value) {
if (key == null) return false;
if (value == null) return false;
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
Object lhs = attachments.get(key);
return attachments.containsKey(key) && value.equals(lhs) && attachments.remove(key) != null;
}
}
void clearAttachments() {
attachments.clear();
}
}