org.springframework.integration.support.MutableMessage.java Source code

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Here is the source code for org.springframework.integration.support.MutableMessage.java

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/*
 * Copyright 2014-2019 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.integration.support;

import java.io.Serializable;
import java.util.Map;
import java.util.UUID;

import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;

/**
 * An implementation of {@link Message} with a generic payload. Unlike
 * {@link org.springframework.messaging.support.GenericMessage},
 * this message (or its headers) can be modified after creation.
 * Great care must be taken, when mutating messages, that some other element/thread is not
 * concurrently using the message. Also note that any in-memory stores (such as
 * {@link org.springframework.integration.store.SimpleMessageStore})
 * may have a reference to the message and changes will be
 * reflected there too.
 *
 * <p>
 * <b>IMPORTANT: Mutable messages may share state (such as message headers); such messages
 * should never be exposed to other components or undesirable side-effects may result.</b>
 * <p>
 * <b>It is generally recommended that messages transferred between components should
 * always be immutable unless great care is taken with their use.</b>
 *
 * @author Gary Russell
 * @author Artem Bilan
 * @author Stuart Williams
 * @author David Turanski
 *
 * @since 4.0
 *
 */
public class MutableMessage<T> implements Message<T>, Serializable {

    private static final long serialVersionUID = -636635024258737500L;

    private final T payload;

    private final MutableMessageHeaders headers;

    public MutableMessage(T payload) {
        this(payload, (Map<String, Object>) null);
    }

    public MutableMessage(T payload, @Nullable Map<String, Object> headers) {
        this(payload, new MutableMessageHeaders(headers));
    }

    protected MutableMessage(T payload, MutableMessageHeaders headers) {
        Assert.notNull(payload, "payload must not be null");
        Assert.notNull(headers, "headers must not be null");
        this.payload = payload;
        this.headers = headers;
    }

    @Override
    public MutableMessageHeaders getHeaders() {
        return this.headers;
    }

    @Override
    public T getPayload() {
        return this.payload;
    }

    Map<String, Object> getRawHeaders() {
        return this.headers.getRawHeaders();
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(getClass().getSimpleName());
        sb.append(" [payload=");
        if (this.payload instanceof byte[]) {
            sb.append("byte[").append(((byte[]) this.payload).length).append("]");
        } else {
            sb.append(this.payload);
        }
        sb.append(", headers=").append(this.headers).append("]");
        return sb.toString();
    }

    @Override
    public int hashCode() {
        return this.headers.hashCode() * 23 + ObjectUtils.nullSafeHashCode(this.payload);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof MutableMessage<?>) {
            MutableMessage<?> other = (MutableMessage<?>) obj;
            UUID thisId = this.headers.getId();
            UUID otherId = other.headers.getId();
            return (ObjectUtils.nullSafeEquals(thisId, otherId) && this.headers.equals(other.headers)
                    && this.payload.equals(other.payload));
        }
        return false;
    }

}