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

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/*
 * 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. The type parameter gives the
     * class of the object that should be produced, the genericType parameter
     * gives the java.lang.reflect.Type of the object that should be produced.
     * E.g. if the object to be produced is List<String>, the type parameter
     * will be java.util.List and the genericType parameter will be
     * java.lang.reflect.ParameterizedType.
     *
     * @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>Method.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>Method.getParameterAnnotations</code>.
     * @param mediaType the media type of the HTTP entity, if one is not
     * specified in the request then <code>application/octet-stream</code> is
     * used.
     * @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>Method.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>Method.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;
    
}