Java example source code file (MIMEPart.java)

This example Java source code file (MIMEPart.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

content\-type, datahead, decodingexception, didn\'t, error, header, illegalstateexception, inputstream, internal, list, log, logger, logging, mimepart, nio, override, string, util

The MIMEPart.java Java example source code

/*
 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.xml.internal.org.jvnet.mimepull;

import java.io.File;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Represents an attachment part in a MIME message. MIME message parsing is done
 * lazily using a pull parser, so the part may not have all the data. {@link #read}
 * and {@link #readOnce} may trigger the actual parsing the message. In fact,
 * parsing of an attachment part may be triggered by calling {@link #read} methods
 * on some other attachment parts. All this happens behind the scenes so the
 * application developer need not worry about these details.
 *
 * @author Jitendra Kotamraju, Martin Grebac
 */
public class MIMEPart {

    private static final Logger LOGGER = Logger.getLogger(MIMEPart.class.getName());

    private volatile InternetHeaders headers;
    private volatile String contentId;
    private String contentType;
    private String contentTransferEncoding;

    volatile boolean parsed;    // part is parsed or not
    final MIMEMessage msg;
    private final DataHead dataHead;

    MIMEPart(MIMEMessage msg) {
        this.msg = msg;
        this.dataHead = new DataHead(this);
    }

    MIMEPart(MIMEMessage msg, String contentId) {
        this(msg);
        this.contentId = contentId;
    }

    /**
     * Can get the attachment part's content multiple times. That means
     * the full content needs to be there in memory or on the file system.
     * Calling this method would trigger parsing for the part's data. So
     * do not call this unless it is required(otherwise, just wrap MIMEPart
     * into a object that returns InputStream for e.g DataHandler)
     *
     * @return data for the part's content
     */
    public InputStream read() {
        InputStream is = null;
        try {
            is = MimeUtility.decode(dataHead.read(), contentTransferEncoding);
        } catch (DecodingException ex) { //ignore
            if (LOGGER.isLoggable(Level.WARNING)) {
                LOGGER.log(Level.WARNING, null, ex);
            }
        }
        return is;
    }

    /**
     * Cleans up any resources that are held by this part (for e.g. deletes
     * the temp file that is used to serve this part's content). After
     * calling this, one shouldn't call {@link #read()} or {@link #readOnce()}
     */
    public void close() {
        dataHead.close();
    }

    /**
     * Can get the attachment part's content only once. The content
     * will be lost after the method. Content data is not be stored
     * on the file system or is not kept in the memory for the
     * following case:
     *   - Attachement parts contents are accessed sequentially
     *
     * In general, take advantage of this when the data is used only
     * once.
     *
     * @return data for the part's content
     */
    public InputStream readOnce() {
        InputStream is = null;
        try {
            is = MimeUtility.decode(dataHead.readOnce(), contentTransferEncoding);
        } catch (DecodingException ex) { //ignore
            if (LOGGER.isLoggable(Level.WARNING)) {
                LOGGER.log(Level.WARNING, null, ex);
            }
        }
        return is;
    }

    public void moveTo(File f) {
        dataHead.moveTo(f);
    }

    /**
     * Returns Content-ID MIME header for this attachment part
     *
     * @return Content-ID of the part
     */
    public String getContentId() {
        if (contentId == null) {
            getHeaders();
        }
        return contentId;
    }

    /**
     * Returns Content-Transfer-Encoding MIME header for this attachment part
     *
     * @return Content-Transfer-Encoding of the part
     */
    public String getContentTransferEncoding() {
        if (contentTransferEncoding == null) {
            getHeaders();
        }
        return contentTransferEncoding;
    }

    /**
     * Returns Content-Type MIME header for this attachment part
     *
     * @return Content-Type of the part
     */
    public String getContentType() {
        if (contentType == null) {
            getHeaders();
        }
        return contentType;
    }

    private void getHeaders() {
        // Trigger parsing for the part headers
        while(headers == null) {
            if (!msg.makeProgress()) {
                if (headers == null) {
                    throw new IllegalStateException("Internal Error. Didn't get Headers even after complete parsing.");
                }
            }
        }
    }

    /**
     * Return all the values for the specified header.
     * Returns <code>null if no headers with the
     * specified name exist.
     *
     * @param   name header name
     * @return  list of header values, or null if none
     */
    public List<String> getHeader(String name) {
        getHeaders();
        assert headers != null;
        return headers.getHeader(name);
    }

    /**
     * Return all the headers
     *
     * @return list of Header objects
     */
    public List<? extends Header> getAllHeaders() {
        getHeaders();
        assert headers != null;
        return headers.getAllHeaders();
    }

    /**
     * Callback to set headers
     *
     * @param headers MIME headers for the part
     */
    void setHeaders(InternetHeaders headers) {
        this.headers = headers;
        List<String> ct = getHeader("Content-Type");
        this.contentType = (ct == null) ? "application/octet-stream" : ct.get(0);
        List<String> cte = getHeader("Content-Transfer-Encoding");
        this.contentTransferEncoding = (cte == null) ? "binary" : cte.get(0);
    }

    /**
     * Callback to notify that there is a partial content for the part
     *
     * @param buf content data for the part
     */
    void addBody(ByteBuffer buf) {
        dataHead.addBody(buf);
    }

    /**
     * Callback to indicate that parsing is done for this part
     * (no more update events for this part)
     */
    void doneParsing() {
        parsed = true;
        dataHead.doneParsing();
    }

    /**
     * Callback to set Content-ID for this part
     * @param cid Content-ID of the part
     */
    void setContentId(String cid) {
        this.contentId = cid;
    }

    /**
     * Callback to set Content-Transfer-Encoding for this part
     * @param cte Content-Transfer-Encoding of the part
     */
    void setContentTransferEncoding(String cte) {
        this.contentTransferEncoding = cte;
    }

    @Override
    public String toString() {
        return "Part="+contentId+":"+contentTransferEncoding;
    }

}