src/jsr311-api/src/javax/ws/rs/ext/MessageBodyWriter.java

/*
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the "License").  You may not use this file except
 * in compliance with the License.
 *
 * You can obtain a copy of the license at
 * http://www.opensource.org/licenses/cddl1.php
 * See the License for the specific language governing
 * permissions and limitations under the License.
 */

/*
 * MessageBodyWriter.java
 *
 * Created on November 8, 2007, 3:57 PM
 *
 */

package javax.ws.rs.ext;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;

/**
 * Contract for a provider that supports the conversion of a Java type to a 
 * stream. To add a <code>MessageBodyWriter</code> implementation, annotate the
 * implementation class with <code>@Provider</code>.
 *
 * A <code>MessageBodyWriter</code> implementation may be annotated
 * with {@link javax.ws.rs.Produces} to restrict the media types for which it will
 * be considered suitable.
 *
 * @param T the type that can be written
 * @see Provider
 * @see javax.ws.rs.Produces
 */
public interface MessageBodyWriter<T> {
    
    /**
     * Ascertain if the MessageBodyWriter supports a particular type.
     *
     * @param type the class of object that is to be written.
     * @param genericType the type of object 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 on the resource
     * method that returns the object.
     * @param mediaType the media type of the HTTP entity.
     * @return true if the type is supported, otherwise false.
     */
    boolean isWriteable(Class<?> type, Type genericType,
            Annotation annotations[], MediaType mediaType);
    
    /**
     * Called before <code>writeTo</code> to ascertain the length in bytes of 
     * the serialized form of <code>t</code>. A non-negative return value is 
     * used in a HTTP <code>Content-Length</code> header.
     * @param t the instance to write
     * @param type the class of object that is to be written.
     * @param genericType the type of object to be written, obtained either
     * by reflection of a resource method return type or by 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 on the resource
     * method that returns the object.
     * @param mediaType the media type of the HTTP entity.
     * @return length in bytes or -1 if the length cannot be determined in
     * advance
     */
    long getSize(T t, Class<?> type, Type genericType, Annotation annotations[], 
            MediaType mediaType);

    /**
     * Write a type to an HTTP response. The response 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 response body.
     * 
     * @param t the instance to write.
     * @param type the class of object that is to be written.
     * @param genericType the type of object to be written, obtained either
     * by reflection of a resource method return type or by 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 on the resource
     * method that returns the object.
     * @param mediaType the media type of the HTTP entity.
     * @param httpHeaders a mutable map of the HTTP response 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 
     * @throws javax.ws.rs.WebApplicationException if a specific 
     * HTTP error response needs to be produced. Only effective if thrown prior
     * to the response being committed.
     */
    void writeTo(T t, Class<?> type, Type genericType, Annotation annotations[], 
            MediaType mediaType, 
            MultivaluedMap<String, Object> httpHeaders,
            OutputStream entityStream) throws IOException, WebApplicationException;    
}