FormDataMultiPart.java

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package com.sun.jersey.multipart;

import com.sun.jersey.core.header.MediaTypes;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.ws.rs.core.MediaType;

/**
 * <p>Subclass of {@link MultiPart} with specialized support for media type
 * <code>multipart/form-data</code>.  See
 * <a href="http://www.ietf.org/rfc/rfc2388.txt">RFC 2388</a>
 * for the formal definition of this media type.</p>
 *
 * <p>For a server side application wishing to process an incoming
 * <code>multipart/form-data</code> message, the following features
 * are provided:</p>
 * <ul>
 * <li>Incoming entities will be of type {@link FormDataMultiPart},
 *     enabling access to the specialized methods.</li>
 * <li>Incoming body parts will be of type {@link FormDataBodyPart},
 *     enabling access to its specialized methods.</li>
 * <li>Convenience method to return the {@link FormDataBodyPart} for a
 *     specified control name.</li>
 * <li>Convenience method to return a <code>Map</code> of {@link FormDataBodyPart}s
 *     for all fields, keyed by field name.</li>
 * </ul>
 *
 * <p>For a client side application wishing to construct an outgoing
 * <code>multipart/form-data</code> message, the following features
 * are provided:</p>
 * <ul>
 * <li>Media type of the {@link FormDataMultiPart} instance will automatically
 *     set to <code>multipart/form-data</code>.</li>
 * <li>Builder pattern method to add simple field values as body parts of
 *     type <code>text/plain</code>.</li>
 * <li>Builder pattern method to add named "file" field values with arbitrary
 *     media types.</li>
 * </ul>
 *
 * <p><strong>FIXME</strong> - Consider supporting the use case of a nested
 * <code>multipart/mixed</code> body part to contain multiple uploaded files.</p>
 */
public class FormDataMultiPart extends MultiPart {


    /**
     * Instantiate a new {@link FormDataMultiPart} instance with
     * default characteristics.
     */
    public FormDataMultiPart() {
        super(MediaType.MULTIPART_FORM_DATA_TYPE);
    }

    /**
     * Builder pattern method to add a named field with a text value,
     * and return this instance.
     *
     * @param name the control name
     * @param value the text value
     * @return this instance.
     */
    public FormDataMultiPart field(String name, String value) {
        getBodyParts().add(new FormDataBodyPart(name, value));
        return this;
    }


    /**
     * Builder pattern method to add a named field with an arbitrary
     * media type and entity, and return this instance.
     *
     * @param name the control name.
     * @param entity entity value for the new field
     * @param mediaType media type for the new field
     * @return this instance.
     */
    public FormDataMultiPart field(String name, Object entity, MediaType mediaType) {
        getBodyParts().add(new FormDataBodyPart(name, entity, mediaType));
        return this;
    }


    /**
     * Get a form data body part given a control name.
     * <p>
     * 
     * @param name the control name.
     * @return the form data body part, otherwise null if no part
     *         is present with the given control name. If more that one
     *         part is present with the same control name, then the first
     *         part that occurs is returned.
     */
    public FormDataBodyPart getField(String name) {
        FormDataBodyPart result = null;
        for (BodyPart bodyPart : getBodyParts()) {
            if (!(bodyPart instanceof FormDataBodyPart)) {
                continue;
            }
            if (name.equals(((FormDataBodyPart) bodyPart).getName())) {
                result = (FormDataBodyPart) bodyPart;
            }
        }
        return result;
    }

    /**
     * Get a list of one or more form data body parts given a control name.
     *
     * @param name the control name.
     * @return the list of form data body parts, otherwise null if no parts
     *         are present with the given control name.
     */
    public List<FormDataBodyPart> getFields(String name) {
        List<FormDataBodyPart> result = null;
        for (BodyPart bodyPart : getBodyParts()) {
            if (!(bodyPart instanceof FormDataBodyPart)) {
                continue;
            }
            if (name.equals(((FormDataBodyPart) bodyPart).getName())) {
                if (result == null)
                    result = new ArrayList<FormDataBodyPart>(1);
                result.add((FormDataBodyPart) bodyPart);
            }
        }
        return result;
    }

    /**
     * Get a map of form data body parts where the key is the control name
     * and the value is a list of one or more form data body parts.
     *
     * @return return the map of form data body parts.
     */
    public Map<String, List<FormDataBodyPart>> getFields() {
        Map<String, List<FormDataBodyPart>> map = new HashMap<String, List<FormDataBodyPart>>();
        for (BodyPart bodyPart : getBodyParts()) {
            if (!(bodyPart instanceof FormDataBodyPart)) {
                continue;
            }

            FormDataBodyPart p = (FormDataBodyPart) bodyPart;
            List<FormDataBodyPart> l = map.get(p.getName());
            if (l == null) {
                l = new ArrayList<FormDataBodyPart>(1);
                map.put(p.getName(), l);
            }
            l.add(p);
        }
        return map;
    }

    /**
     * Disable changing the media type to anything other than
     * <code>multipart/form-data</code>.
     *
     * @param mediaType The proposed media type
     *
     * @exception IllegalArgumentException if the proposed media type is not
     *  <code>multipart/form-data</code>
     */
    @Override
    public void setMediaType(MediaType mediaType) {
        if (!MediaTypes.typeEquals(mediaType, MediaType.MULTIPART_FORM_DATA_TYPE)) {
            throw new IllegalArgumentException("Cannot change media type of a FormDataMultiPart instance");
        }
        super.setMediaType(mediaType);
    }
}