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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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package org.apache.axiom.attachments;


import javax.activation.DataHandler;
import javax.activation.DataSource;

import org.apache.axiom.attachments.lifecycle.DataHandlerExt;

 * {@link DataHandler} implementation for MIME parts read from a stream.
class PartDataHandler extends DataHandler implements DataHandlerExt {
    private final PartImpl part;
    private DataSource dataSource;

    public PartDataHandler(PartImpl part) {
        // We can't call PartImpl#getDataSource() here because it would fetch the content of the
        // part and therefore disable streaming. We can't pass null here either because Geronimo's
        // DataHandler implementation would throw a NullPointerException. Therefore we create the
        // default PartDataSource. When the DataSource is requested, we check if for there is an
        // implementation specific to the buffering strategy and return that instead of the default
        // implementation.
        super(new PartDataSource(part));
        this.part = part;

    public DataSource getDataSource() {
        if (dataSource == null) {
            dataSource = part.getDataSource();
            if (dataSource == null) {
                // We get here if there is no DataSource implementation specific to the buffering
                // strategy being used. In this case we use super.getDataSource() to get the
                // default PartDataSource that we created in the constructor.
                dataSource = super.getDataSource();
        return dataSource;

    public void writeTo(OutputStream os) throws IOException {
        // The PartContent may have an implementation of writeTo that is more efficient than the default
        // DataHandler#writeTo method (which requests an input stream and then copies it to the output
        // stream).

    public InputStream readOnce() throws IOException {
        return part.getInputStream(false);

    public void purgeDataSource() throws IOException {

    public void deleteWhenReadOnce() throws IOException {
        // As shown in AXIOM-381, in all released versions of Axiom, deleteWhenReadOnce
        // always has the same effect as purgeDataSource