http://rest-easy.org/resteasy-multipart-provider: (JBoss by Red Hat)
  • Heiko Braun
  • Martin Algesten 
package org.jboss.resteasy.plugins.providers.multipart;

import org.jboss.resteasy.plugins.providers.AbstractEntityProvider;
import org.jboss.resteasy.plugins.providers.ProviderHelper;
import org.jboss.resteasy.resteasy_jaxrs.i18n.LogMessages;
import org.jboss.resteasy.spi.AsyncOutputStream;
import org.jboss.resteasy.spi.ReaderException;
import org.jboss.resteasy.spi.WriterException;

import javax.activation.DataSource;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMultipart;
import javax.mail.util.ByteArrayDataSource;
import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;
import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.concurrent.CompletionStage;


A provider to handle multipart representations. This implementation will be invoked when a method parameter takes a MimeMultipart as a method parameter or a return value and the @Consumes value is either multipart/mixed or multipart/form-data. 

 @POST @Consumes("multipart/form-data") public void postData(MimeMultipart multipart) { ... 

 When the MimeMultipart is passed to the method body, it is up to the developer to extract the various parts. 
Author:Ryan J. McDonough
/**
 * A provider to handle multipart representations. This implementation will be
 * invoked when a method parameter takes a {@link MimeMultipart} as a method
 * parameter or a return value and the
 *
 * {@literal @}Consumes value is either multipart/mixed or multipart/form-data.
 * <p>
 * <code>
 * {@literal @}POST
 * {@literal @}Consumes("multipart/form-data") public void postData(MimeMultipart multipart) {
 * ...
 * </code>
 * <p>
 * When the {@link MimeMultipart} is passed to the method body, it is up to the
 * developer to extract the various parts.
 *
 * @author <a href="mailto:ryan@damnhandy.com">Ryan J. McDonough</a>
 */

@Provider
@Produces("multipart/mixed")
@Consumes({"multipart/mixed", "multipart/form-data"})
public class MimeMultipartProvider extends AbstractEntityProvider<MimeMultipart>
{

   
Params:
  • in – input stream
  • mediaType – media type
Throws:
Returns:data source
/**
    * @param in input stream
    * @param mediaType media type
    * @return data source
    * @throws IOException if I/O error occurred
    */
   public static DataSource readDataSource(InputStream in, MediaType mediaType) throws IOException
   {
      ByteArrayDataSource ds = new ByteArrayDataSource(new BufferedInputStream(in), mediaType
              .toString());

      return ds;
   }

   
Ascertain if the MessageBodyReader can produce an instance of a particular type. The type parameter gives the class of the instance that should be produced, the genericType parameter gives the java.lang.reflect.Type of the instance that should be produced. E.g. if the instance to be produced is List<String>, the type parameter will be java.util.List and the genericType parameter will be java.lang.reflect.ParameterizedType. 
Params:
  • type –        the class of instance to be produced.
  • genericType – the type of instance to be produced. E.g. if the message body is to be converted into a method parameter, this will be the formal type of the method parameter as returned by Method.getGenericParameterTypes.
  • annotations – an array of the annotations on the declaration of the artifact that will be initialized with the produced instance. E.g. if the message body is to be converted into a method parameter, this will be the annotations on that parameter returned by Method.getParameterAnnotations.
  • mediaType –  the media type of the HTTP entity, if one is not specified in the request then application/octet-stream is used.
Returns:true if the type is supported, otherwise false.
/**
    * Ascertain if the MessageBodyReader can produce an instance of a
    * particular type. The {@code type} parameter gives the
    * class of the instance that should be produced, the {@code genericType} parameter
    * gives the {@link java.lang.reflect.Type java.lang.reflect.Type} of the instance
    * that should be produced.
    * E.g. if the instance to be produced is {@code List<String>}, the {@code type} parameter
    * will be {@code java.util.List} and the {@code genericType} parameter will be
    * {@link java.lang.reflect.ParameterizedType java.lang.reflect.ParameterizedType}.
    *
    * @param type        the class of instance to be produced.
    * @param genericType the type of instance to be produced. E.g. if the
    *                    message body is to be converted into a method parameter, this will be
    *                    the formal type of the method parameter as returned by
    *                    {@code Method.getGenericParameterTypes}.
    * @param annotations an array of the annotations on the declaration of the
    *                    artifact that will be initialized with the produced instance. E.g. if the
    *                    message body is to be converted into a method parameter, this will be
    *                    the annotations on that parameter returned by
    *                    {@code Method.getParameterAnnotations}.
    * @param mediaType   the media type of the HTTP entity, if one is not
    *                    specified in the request then {@code application/octet-stream} is
    *                    used.
    * @return {@code true} if the type is supported, otherwise {@code false}.
    */
   public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType)
   {
      return MimeMultipart.class.equals(type);
   }

   
Ascertain if the MessageBodyWriter supports a particular type.

Params:
  • type –        the class of instance that is to be written.
  • genericType – the type of instance to be written, obtained either by reflection of a resource method return type or via inspection of the returned instance. GenericEntity provides a way to specify this information at runtime.
  • annotations – an array of the annotations attached to the message entity instance.
  • mediaType –   the media type of the HTTP entity.
Returns:true if the type is supported, otherwise false.
/**
    * Ascertain if the MessageBodyWriter supports a particular type.
    *
    * @param type        the class of instance that is to be written.
    * @param genericType the type of instance to be written, obtained either
    *                    by reflection of a resource method return type or via inspection
    *                    of the returned instance. {@link javax.ws.rs.core.GenericEntity}
    *                    provides a way to specify this information at runtime.
    * @param annotations an array of the annotations attached to the message entity instance.
    * @param mediaType   the media type of the HTTP entity.
    * @return {@code true} if the type is supported, otherwise {@code false}.
    */
   public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType)
   {
      return MimeMultipart.class.equals(type);
   }

   
Read a type from the InputStream. 
 In case the entity input stream is empty, the reader is expected to either return a Java representation of a zero-length entity or throw a NoContentException in case no zero-length entity representation is defined for the supported Java type. A NoContentException, if thrown by a message body reader while reading a server request entity, is automatically translated by JAX-RS server runtime into a BadRequestException wrapping the original NoContentException and rethrown for a standard processing by the registered exception mappers. 


Params:
  • type –         the type that is to be read from the entity stream.
  • genericType –  the type of instance to be produced. E.g. if the message body is to be converted into a method parameter, this will be the formal type of the method parameter as returned by Method.getGenericParameterTypes.
  • annotations –  an array of the annotations on the declaration of the artifact that will be initialized with the produced instance. E.g. if the message body is to be converted into a method parameter, this will be the annotations on that parameter returned by Method.getParameterAnnotations.
  • mediaType –    the media type of the HTTP entity.
  • httpHeaders –  the read-only HTTP headers associated with HTTP entity.
  • entityStream – the InputStream of the HTTP entity. The caller is responsible for ensuring that the input stream ends when the entity has been consumed. The implementation should not close the input stream.
Throws:
  • IOException – if an IO error arises. In case the entity input stream is empty and the reader is not able to produce a Java representation for a zero-length entity, NoContentException is expected to be thrown.
Returns:the type that was read from the stream. In case the entity input stream is empty, the reader is expected to either return an instance representing a zero-length entity or throw a NoContentException in case no zero-length entity representation is defined for the supported Java type.
/**
    * Read a type from the {@link InputStream}.
    * <p>
    * In case the entity input stream is empty, the reader is expected to either return a
    * Java representation of a zero-length entity or throw a {@link javax.ws.rs.core.NoContentException}
    * in case no zero-length entity representation is defined for the supported Java type.
    * A {@code NoContentException}, if thrown by a message body reader while reading a server
    * request entity, is automatically translated by JAX-RS server runtime into a {@link javax.ws.rs.BadRequestException}
    * wrapping the original {@code NoContentException} and rethrown for a standard processing by
    * the registered {@link javax.ws.rs.ext.ExceptionMapper exception mappers}.
    * </p>
    *
    * @param type         the type that is to be read from the entity stream.
    * @param genericType  the type of instance to be produced. E.g. if the
    *                     message body is to be converted into a method parameter, this will be
    *                     the formal type of the method parameter as returned by
    *                     {@code Method.getGenericParameterTypes}.
    * @param annotations  an array of the annotations on the declaration of the
    *                     artifact that will be initialized with the produced instance. E.g.
    *                     if the message body is to be converted into a method parameter, this
    *                     will be the annotations on that parameter returned by
    *                     {@code Method.getParameterAnnotations}.
    * @param mediaType    the media type of the HTTP entity.
    * @param httpHeaders  the read-only HTTP headers associated with HTTP entity.
    * @param entityStream the {@link InputStream} of the HTTP entity. The
    *                     caller is responsible for ensuring that the input stream ends when the
    *                     entity has been consumed. The implementation should not close the input
    *                     stream.
    * @return the type that was read from the stream. In case the entity input stream is empty, the reader
    *         is expected to either return an instance representing a zero-length entity or throw
    *         a {@link javax.ws.rs.core.NoContentException} in case no zero-length entity representation is
    *         defined for the supported Java type.
    * @throws java.io.IOException if an IO error arises. In case the entity input stream is empty
    *                             and the reader is not able to produce a Java representation for
    *                             a zero-length entity, {@code NoContentException} is expected to
    *                             be thrown.
    */
   public MimeMultipart readFrom(Class<MimeMultipart> type,
                                 Type genericType,
                                 Annotation[] annotations,
                                 MediaType mediaType,
                                 MultivaluedMap<String, String> httpHeaders,
                                 InputStream entityStream) throws IOException
   {
      try
      {
         LogMessages.LOGGER.debugf("Provider : %s,  Method : readFrom", getClass().getName());
         DataSource ds = readDataSource(entityStream, mediaType);
         return new MimeMultipart(ds);
      }
      catch (MessagingException e)
      {
         throw new ReaderException(e);
      }
   }

   
Write a type to an HTTP message. The message header map is mutable
but any changes must be made before writing to the output stream since
the headers will be flushed prior to writing the message body.

Params:
  • mimeMultipart – the instance to write.
  • type –         the class of instance that is to be written.
  • genericType –  the type of instance to be written. GenericEntity provides a way to specify this information at runtime.
  • annotations –  an array of the annotations attached to the message entity instance.
  • mediaType –    the media type of the HTTP entity.
  • httpHeaders –  a mutable map of the HTTP message headers.
  • entityStream – the OutputStream for the HTTP entity. The implementation should not close the output stream.
Throws:
/**
    * Write a type to an HTTP message. The message header map is mutable
    * but any changes must be made before writing to the output stream since
    * the headers will be flushed prior to writing the message body.
    *
    * @param mimeMultipart the instance to write.
    * @param type         the class of instance that is to be written.
    * @param genericType  the type of instance to be written. {@link javax.ws.rs.core.GenericEntity}
    *                     provides a way to specify this information at runtime.
    * @param annotations  an array of the annotations attached to the message entity instance.
    * @param mediaType    the media type of the HTTP entity.
    * @param httpHeaders  a mutable map of the HTTP message headers.
    * @param entityStream the {@link OutputStream} for the HTTP entity. The
    *                     implementation should not close the output stream.
    * @throws java.io.IOException if an IO error arises.
    */
   public void writeTo(MimeMultipart mimeMultipart,
                       Class<?> type,
                       Type genericType,
                       Annotation[] annotations,
                       MediaType mediaType,
                       MultivaluedMap<String, Object> httpHeaders,
                       OutputStream entityStream) throws IOException
   {
      try
      {
         LogMessages.LOGGER.debugf("Provider : %s,  Method : writeTo", getClass().getName());
         // replace the Content-Type header to include the boundry
         // information
         httpHeaders.putSingle("Content-Type", MediaType.valueOf(mimeMultipart.getContentType()));
         mimeMultipart.writeTo(entityStream);
      }
      catch (MessagingException e)
      {
         throw new WriterException(e);
      }

   }

   @Override
   public CompletionStage<Void> asyncWriteTo(MimeMultipart mimeMultipart, Class<?> type, Type genericType, Annotation[] annotations,
                                             MediaType mediaType, MultivaluedMap<String, Object> httpHeaders,
                                             AsyncOutputStream entityStream) {
       try
       {
          LogMessages.LOGGER.debugf("Provider : %s,  Method : writeTo", getClass().getName());
          // replace the Content-Type header to include the boundry
          // information
          httpHeaders.putSingle("Content-Type", MediaType.valueOf(mimeMultipart.getContentType()));
          ByteArrayOutputStream bos = new ByteArrayOutputStream(2048);
          mimeMultipart.writeTo(bos);
          return entityStream.asyncWrite(bos.toByteArray());
       }
       catch (MessagingException | IOException e)
       {
          return ProviderHelper.completedException(new WriterException(e));
       }
   }
}