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/*
 * Providers.java
 * 
 * Created on March 5, 2008, 9:00 AM
 * 
 */

package javax.ws.rs.ext;

import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import javax.ws.rs.core.MediaType;

/**
 * An injectable interface providing runtime lookup of provider instances. 
 * 
 * @see javax.ws.rs.core.Context
 * @see MessageBodyReader
 * @see MessageBodyWriter
 * @see ContextResolver
 * @see ExceptionMapper
 */
public interface Providers {
    
    /**
     * Get a message body reader that matches a set of criteria. The set of
     * readers is first filtered by comparing the supplied value of
     * {@code mediaType} with the value of each reader's 
     * {@link javax.ws.rs.Consumes}, ensuring the supplied value of
     * {@code type} is assignable to the generic type of the reader, and 
     * eliminating those that do not match.
     * The list of matching readers is then ordered with those with the best 
     * matching values of {@link javax.ws.rs.Consumes} (x/y > x/* > */*)
     * sorted first. Finally, the 
     * {@link MessageBodyReader#isReadable}
     * method is called on each reader in order using the supplied criteria and
     * the first reader that returns {@code true} is selected and returned.
     * 
     * @param type the class of object that is to be read.
     * @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 
     * Class.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 
     * Class.getParameterAnnotations.
     * @param mediaType the media type of the data that will be read.
     * @return a MessageBodyReader that matches the supplied criteria or null
     * if none is found.
     */
     MessageBodyReader getMessageBodyReader(Class type, 
            Type genericType, Annotation annotations[], MediaType mediaType);
    
    /**
     * Get a message body writer that matches a set of criteria. The set of
     * writers is first filtered by comparing the supplied value of
     * {@code mediaType} with the value of each writer's 
     * {@link javax.ws.rs.Produces}, ensuring the supplied value of
     * {@code type} is assignable to the generic type of the reader, and 
     * eliminating those that do not match.
     * The list of matching writers is then ordered with those with the best 
     * matching values of {@link javax.ws.rs.Produces} (x/y > x/* > */*)
     * sorted first. Finally, the 
     * {@link MessageBodyWriter#isWriteable}
     * method is called on each writer in order using the supplied criteria and
     * the first writer that returns {@code true} is selected and returned.
     * 
     * @param type the class of object that is to be written.
     * @param genericType the type of object to be written. E.g. if the 
     * message body is to be produced from a field, this will be
     * the declared type of the field as returned by 
     * Field.getGenericType.
     * @param annotations an array of the annotations on the declaration of the
     * artifact that will be written. E.g. if the 
     * message body is to be produced from a field, this will be
     * the annotations on that field returned by 
     * Field.getDeclaredAnnotations.
     * @param mediaType the media type of the data that will be written.
     * @return a MessageBodyReader that matches the supplied criteria or null
     * if none is found.
     */
     MessageBodyWriter getMessageBodyWriter(Class type, 
            Type genericType, Annotation annotations[], MediaType mediaType);
    
    /**
     * Get an exception mapping provider for a particular class of exception. 
     * Returns the provider whose generic type is the nearest superclass of
     * {@code type}.
     * @param type the class of exception
     * @return an {@link ExceptionMapper} for the supplied type or null if none
     * is found.
     */
     ExceptionMapper getExceptionMapper(Class type);

    /**
     * Get a context resolver for a particular type of context and media type.
     * The set of resolvers is first filtered by comparing the supplied value of
     * {@code mediaType} with the value of each resolver's 
     * {@link javax.ws.rs.Produces}, ensuring the generic type of the context 
     * resolver is assignable to the supplied value of {@code contextType}, and 
     * eliminating those that do not match. If only one resolver matches the 
     * criteria then it is returned. If more than one resolver matches then the
     * list of matching resolvers is ordered with those with the best 
     * matching values of {@link javax.ws.rs.Produces} (x/y > x/* > */*)
     * sorted first. A proxy is returned that delegates calls to
     * {@link ContextResolver#getContext(java.lang.Class)} to each matching context
     * resolver in order and returns the first non-null value it obtains or null
     * if all matching context resolvers return null.
     * 
     * @param contextType the class of context desired
     * @param mediaType the media type of data for which a context is required.
     * @return a matching context resolver instance or null if no matching 
     * context providers are found.
     */
     ContextResolver getContextResolver(Class contextType, 
            MediaType mediaType);
}