src/jsr311-api/src/javax/ws/rs/ext/MessageBodyReader.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.
 */

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

package javax.ws.rs.ext;

import java.io.IOException;
import java.io.InputStream;
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 stream to a 
 * Java type. To add a <code>MessageBodyReader</code> implementation, annotate the
 * implementation class with <code>@Provider</code>.
 *
 * A <code>MessageBodyReader</code> implementation may be annotated
 * with {@link javax.ws.rs.Consumes} to restrict the media types for which it will
 * be considered suitable.
 *
 * @see Provider
 * @see javax.ws.rs.Consumes
 */
public interface MessageBodyReader<T> {
    
    /**
     * Ascertain if the MessageBodyReader can produce an instance of a particular type.
     *
     * @param type the class of object to be produced.
     * @param genericType the type of object 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>Class.getGenericParameterTypes</code>.
     * @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>Class.getParameterAnnotations</code>.
     * @param mediaType the media type of the HTTP entity.
     * @return true if the type is supported, otherwise false.
     */
    boolean isReadable(Class<?> type, Type genericType, 
            Annotation annotations[], MediaType mediaType);

    /**
     * Read a type from the {@link InputStream}.
     * 
     * @return the type that was read from the stream.
     * @param type the type that is to be read from the entity stream. 
     * @param genericType the type of object 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>Class.getGenericParameterTypes</code>.
     * @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>Class.getParameterAnnotations</code>.
     * @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.
     * @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.
     */
    T readFrom(Class<T> type, Type genericType,  
            Annotation annotations[], MediaType mediaType,
            MultivaluedMap<String, String> httpHeaders, 
            InputStream entityStream) throws IOException, WebApplicationException;
    
}