examples/src/main/java/org/apache/james/mime4j/samples/dom/MultipartMessage.java

/****************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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.apache.james.mime4j.samples.dom;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Date;

import javax.imageio.ImageIO;

import org.apache.james.mime4j.dom.BinaryBody;
import org.apache.james.mime4j.dom.MessageWriter;
import org.apache.james.mime4j.dom.Multipart;
import org.apache.james.mime4j.dom.TextBody;
import org.apache.james.mime4j.field.address.AddressBuilder;
import org.apache.james.mime4j.message.BodyPart;
import org.apache.james.mime4j.message.MessageImpl;
import org.apache.james.mime4j.message.DefaultMessageWriter;
import org.apache.james.mime4j.message.MultipartImpl;
import org.apache.james.mime4j.storage.Storage;
import org.apache.james.mime4j.storage.StorageBodyFactory;
import org.apache.james.mime4j.storage.StorageOutputStream;
import org.apache.james.mime4j.storage.StorageProvider;

/**
 * Creates a multipart/mixed message that consists of a text/plain and an
 * image/png part. The image is created on the fly; a similar technique can be
 * used to create PDF or XML attachments, for example.
 */
public class MultipartMessage {

    public static void main(String[] args) throws Exception {
        // 1) start with an empty message

        MessageImpl message = new MessageImpl();

        // 2) set header fields

        // Date and From are required fields
        message.setDate(new Date());
        message.setFrom(AddressBuilder.DEFAULT.parseMailbox("John Doe <jdoe@machine.example>"));

        // Message-ID should be present
        message.createMessageId("machine.example");

        // set some optional fields
        message.setTo(AddressBuilder.DEFAULT.parseMailbox("Mary Smith <mary@example.net>"));
        message.setSubject("An image for you");

        // 3) set a multipart body

        Multipart multipart = new MultipartImpl("mixed");

        // a multipart may have a preamble
        multipart.setPreamble("This is a multi-part message in MIME format.");

        // first part is text/plain
        StorageBodyFactory bodyFactory = new StorageBodyFactory();
        BodyPart textPart = createTextPart(bodyFactory, "Why so serious?");
        multipart.addBodyPart(textPart);

        // second part is image/png (image is created on the fly)
        BufferedImage image = renderSampleImage();
        BodyPart imagePart = createImagePart(bodyFactory, image);
        multipart.addBodyPart(imagePart);

        // setMultipart also sets the Content-Type header field
        message.setMultipart(multipart);

        // 4) print message to standard output

        MessageWriter writer = new DefaultMessageWriter();
        writer.writeMessage(message, System.out);

        // 5) message is no longer needed and should be disposed of

        message.dispose();
    }

    /**
     * Creates a text part from the specified string.
     */
    private static BodyPart createTextPart(StorageBodyFactory bodyFactory, String text) {
        // Use UTF-8 to encode the specified text
        TextBody body = bodyFactory.textBody(text, "UTF-8");

        // Create a text/plain body part
        BodyPart bodyPart = new BodyPart();
        bodyPart.setText(body);
        bodyPart.setContentTransferEncoding("quoted-printable");

        return bodyPart;
    }

    /**
     * Creates a binary part from the specified image.
     */
    private static BodyPart createImagePart(StorageBodyFactory bodyFactory,
            BufferedImage image) throws IOException {
        // Create a binary message body from the image
        StorageProvider storageProvider = bodyFactory.getStorageProvider();
        Storage storage = storeImage(storageProvider, image, "png");
        BinaryBody body = bodyFactory.binaryBody(storage);

        // Create a body part with the correct MIME-type and transfer encoding
        BodyPart bodyPart = new BodyPart();
        bodyPart.setBody(body, "image/png");
        bodyPart.setContentTransferEncoding("base64");

        // Specify a filename in the Content-Disposition header (implicitly sets
        // the disposition type to "attachment")
        bodyPart.setFilename("smiley.png");

        return bodyPart;
    }

    /**
     * Stores the specified image in a Storage object.
     */
    private static Storage storeImage(StorageProvider storageProvider,
            BufferedImage image, String formatName) throws IOException {
        // An output stream that is capable of building a Storage object.
        StorageOutputStream out = storageProvider.createStorageOutputStream();

        // Write the image to our output stream. A StorageOutputStream can be
        // used to create attachments using any API that supports writing a
        // document to an output stream, e.g. iText's PdfWriter.
        ImageIO.write(image, formatName, out);

        // Implicitly closes the output stream and returns the data that has
        // been written to it.
        return out.toStorage();
    }

    /**
     * Draws an image; unrelated to Mime4j.
     */
    private static BufferedImage renderSampleImage() {
        System.setProperty("java.awt.headless", "true");

        final int size = 100;

        BufferedImage img = new BufferedImage(size, size,
                BufferedImage.TYPE_BYTE_GRAY);

        Graphics2D gfx = img.createGraphics();
        gfx.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        gfx.setStroke(new BasicStroke(size / 40f, BasicStroke.CAP_ROUND,
                BasicStroke.JOIN_ROUND));

        gfx.setColor(Color.BLACK);
        gfx.setBackground(Color.WHITE);
        gfx.clearRect(0, 0, size, size);

        int b = size / 30;
        gfx.drawOval(b, b, size - 1 - 2 * b, size - 1 - 2 * b);

        int esz = size / 7;
        int ex = (int) (0.27f * size);
        gfx.drawOval(ex, ex, esz, esz);
        gfx.drawOval(size - 1 - esz - ex, ex, esz, esz);

        b = size / 5;
        gfx.drawArc(b, b, size - 1 - 2 * b, size - 1 - 2 * b, 200, 140);

        return img;
    }

}