apache-mime4j-0.6/src/main/java/org/apache/james/mime4j/message/BodyCopier.java

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 * regarding copyright ownership.  The ASF licenses this file   *
 * to you under the Apache License, Version 2.0 (the            *
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package org.apache.james.mime4j.message;

/**
 * Utility class for copying message bodies.
 */
public class BodyCopier {

    private BodyCopier() {
    }

    /**
     * Returns a copy of the given {@link Body} that can be used (and modified)
     * independently of the original. The copy should be
     * {@link Disposable#dispose() disposed of} when it is no longer needed.
     * <p>
     * The {@link Body#getParent() parent} of the returned copy is
     * <code>null</code>, that is, the copy is detached from the parent
     * entity of the original.
     * 
     * @param body
     *            body to copy.
     * @return a copy of the given body.
     * @throws UnsupportedOperationException
     *             if <code>body</code> is an instance of {@link SingleBody}
     *             that does not support the {@link SingleBody#copy() copy()}
     *             operation (or contains such a <code>SingleBody</code>).
     * @throws IllegalArgumentException
     *             if <code>body</code> is <code>null</code> or
     *             <code>body</code> is a <code>Body</code> that is neither
     *             a {@link Message}, {@link Multipart} or {@link SingleBody}
     *             (or contains such a <code>Body</code>).
     */
    public static Body copy(Body body) {
        if (body == null)
            throw new IllegalArgumentException("Body is null");

        if (body instanceof Message)
            return new Message((Message) body);

        if (body instanceof Multipart)
            return new Multipart((Multipart) body);

        if (body instanceof SingleBody)
            return ((SingleBody) body).copy();

        throw new IllegalArgumentException("Unsupported body class");
    }

}