https://projects.eclipse.org/projects/ee4j.jersey/jersey-server: Jersey core server implementation (Eclipse Foundation) 
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 * Copyright (c) 2011, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.jersey.server.model;

import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import javax.ws.rs.core.GenericType;
import javax.ws.rs.core.Request;

import org.glassfish.jersey.internal.util.ReflectionHelper;
import org.glassfish.jersey.internal.util.collection.ClassTypePair;
import org.glassfish.jersey.process.Inflector;


A common interface for invocable resource components. This includes resource
methods, sub-resource methods and sub-resource locators bound to a concrete
handler class and a Java method (either directly or indirectly) declared &
implemented by the handler class.


Invocable component information is used at runtime by a Java method dispatcher
when processing requests.

 Class defines two kinds of java methods: definition method and handling method. Definition method is the java Method that is defined by the user to be executed. This can be java Method of the class but also method of the interface. If it is the method of the interface (method handler class is the class but method itself is from the interface) then the definition method is the method from the inherited class. In other words, the handling method is the concrete method but definition method can be its parent abstract definition. However, in most cases these methods are the same. 


Author:Marek Potociar
See Also:
/**
 * A common interface for invocable resource components. This includes resource
 * methods, sub-resource methods and sub-resource locators bound to a concrete
 * handler class and a Java method (either directly or indirectly) declared &
 * implemented by the handler class.
 * <p/>
 * Invocable component information is used at runtime by a Java method dispatcher
 * when processing requests.
 * <p>
 * Class defines two kinds of {@link Method java methods}: {@link #getDefinitionMethod() definition method} and
 * {@link #getHandlingMethod() handling method}. Definition method is the java {@code Method} that is defined
 * by the user to be
 * executed. This can be java {@code Method} of the class but also method of the interface. If it is the
 * method of the interface (method handler class is the {@code class} but method itself is from
 * the {@code interface}) then the definition method is the method from the inherited {@code class}. In other words, the
 * handling method is the concrete method but definition method can be its parent abstract definition. However, in most
 * cases these methods are the same.
 * </p>
 *
 *
 * @author Marek Potociar
 * @see ResourceMethod
 * @see org.glassfish.jersey.server.spi.internal.ResourceMethodDispatcher
 */
public final class Invocable implements Parameterized, ResourceModelComponent {

    
Method instance representing the Inflector.apply(Object) method. 
/**
     * Method instance representing the {@link Inflector#apply(Object)} method.
     */
    static final Method APPLY_INFLECTOR_METHOD = initApplyMethod();

    private static Method initApplyMethod() {
        try {
            return Inflector.class.getMethod("apply", Object.class);
        } catch (NoSuchMethodException e) {
            IncompatibleClassChangeError error = new IncompatibleClassChangeError("Inflector.apply(Object) method not found");
            error.initCause(e);
            throw error;
        }
    }

    
Create a new resource method invocable model backed by an inflector instance.

Params:
  • inflector – inflector processing the request method.
Returns:Invocable.
/**
     * Create a new resource method invocable model backed by an inflector instance.
     *
     * @param inflector inflector processing the request method.
     *
     * @return Invocable.
     */
    public static <T> Invocable create(Inflector<Request, T> inflector) {
        return create(MethodHandler.create(inflector), APPLY_INFLECTOR_METHOD, false);
    }

    
Create a new resource method invocable model backed by an inflector class.

Params:
  • inflectorClass – inflector syb-type processing the request method.
Returns:Invocable.
/**
     * Create a new resource method invocable model backed by an inflector class.
     *
     * @param inflectorClass inflector syb-type processing the request method.
     * @return Invocable.
     */
    public static Invocable create(Class<? extends Inflector> inflectorClass) {
        return create(MethodHandler.create(inflectorClass), APPLY_INFLECTOR_METHOD, false);
    }

    
Create a new resource method invocable model. Parameter values will be
automatically decoded.

Params:
  • handler –        resource method handler.
  • handlingMethod – handling Java method.
Returns:Invocable.
/**
     * Create a new resource method invocable model. Parameter values will be
     * automatically decoded.
     *
     * @param handler        resource method handler.
     * @param handlingMethod handling Java method.
     * @return Invocable.
     */
    public static Invocable create(MethodHandler handler, Method handlingMethod) {
        return create(handler, handlingMethod, false);
    }

    
Create a new resource method invocable model.

Params:
  • handler –           resource method handler.
  • definitionMethod –  method that is defined to be executed on the handler.
  • encodedParameters – true if the automatic parameter decoding should be disabled, false otherwise.
Returns:Invocable
/**
     * Create a new resource method invocable model.
     *
     * @param handler           resource method handler.
     * @param definitionMethod  method that is defined to be executed on the {@code handler}.
     * @param encodedParameters {@code true} if the automatic parameter decoding
     *                          should be disabled, false otherwise.
     * @return Invocable
     */
    public static Invocable create(MethodHandler handler, Method definitionMethod, boolean encodedParameters) {
        return create(handler, definitionMethod, null, encodedParameters);
    }

    
Create a new resource method invocable model.

Params:
  • handler –           resource method handler.
  • definitionMethod –  method that is defined to be executed on the handler.
  • handlingMethod –  specific and concrete method to be actually executed as a resource method. If null then the definitionMethod will be used.
  • encodedParameters – true if the automatic parameter decoding should be disabled, false otherwise.
Returns:Invocable.
/**
     * Create a new resource method invocable model.
     *
     * @param handler           resource method handler.
     * @param definitionMethod  method that is defined to be executed on the {@code handler}.
     * @param handlingMethod    specific and concrete method to be actually executed as a resource method. If {@code null}
     *                          then the {@code definitionMethod} will be used.
     * @param encodedParameters {@code true} if the automatic parameter decoding
     *                          should be disabled, false otherwise.
     * @return Invocable.
     */
    public static Invocable create(MethodHandler handler, Method definitionMethod, Method handlingMethod,
                                   boolean encodedParameters) {
        return new Invocable(handler, definitionMethod, handlingMethod, encodedParameters, null);
    }

    
Create a new resource method invocable model.

Params:
  • handler –           resource method handler.
  • definitionMethod –  method that is defined to be executed on the handler.
  • handlingMethod –  specific and concrete method to be actually executed as a resource method. If null then the definitionMethod will be used.
  • encodedParameters – true if the automatic parameter decoding should be disabled, false otherwise.
  • routingResponseType – response type that will be used during the routing for purpose of selection of the resource method to be executed. If this parameter is non-null then it will override the return type of the the Java handling method) for purposes of resource method selection. This might be useful in cases when resource method returns a type A but thanks to registered providers (eg. WriterInterceptor) it will be always converted to type B. Then the method selecting algorithm would check presence of MessageBodyWriter for type A (which will never be actually needed) and might result in choosing undesired method. If the parameter is null then the default response type will be used.
Returns:Invocable.
/**
     * Create a new resource method invocable model.
     *
     * @param handler           resource method handler.
     * @param definitionMethod  method that is defined to be executed on the {@code handler}.
     * @param handlingMethod    specific and concrete method to be actually executed as a resource method. If {@code null}
     *                          then the {@code definitionMethod} will be used.
     * @param encodedParameters {@code true} if the automatic parameter decoding
     *                          should be disabled, false otherwise.
     * @param routingResponseType response type that will be used during the routing for purpose
     *                            of selection of the resource method to be executed. If this parameter is
     *                            non-{@code null} then it will override the return type of the
     *                            {@link #getHandlingMethod() the Java handling method}) for purposes of
     *                            resource method selection. This might be useful in cases when resource
     *                            method returns a type {@code A} but thanks to registered providers
     *                            (eg. {@link javax.ws.rs.ext.WriterInterceptor}) it will be always converted
     *                            to type {@code B}. Then the method selecting algorithm would check presence of
     *                            {@link javax.ws.rs.ext.MessageBodyWriter} for type {@code A} (which will
     *                            never be actually needed) and might result in choosing undesired method.
     *                            If the parameter is {@code null} then the default response type will be used.
     *
     * @return Invocable.
     */
    public static Invocable create(MethodHandler handler, Method definitionMethod, Method handlingMethod,
                                   boolean encodedParameters, Type routingResponseType) {
        return new Invocable(handler, definitionMethod, handlingMethod, encodedParameters, routingResponseType);
    }

    private final MethodHandler handler;
    private final Method definitionMethod;
    private final Method handlingMethod;
    private final List<Parameter> parameters;

    private final Class<?> rawResponseType;
    private final Type responseType;
    private final Type routingResponseType;
    private final Class<?> rawRoutingResponseType;

    private Invocable(MethodHandler handler, Method definitionMethod, Method handlingMethod, boolean encodedParameters,
                      Type routingResponseType) {
        this.handler = handler;
        this.definitionMethod = definitionMethod;
        this.handlingMethod = handlingMethod == null ? ReflectionHelper
                .findOverridingMethodOnClass(handler.getHandlerClass(), definitionMethod) : handlingMethod;

        final Class<?> handlerClass = handler.getHandlerClass();
        final Class<?> definitionClass = definitionMethod.getDeclaringClass();
        final ClassTypePair handlingCtPair = ReflectionHelper.resolveGenericType(
                handlerClass,
                this.handlingMethod.getDeclaringClass(),
                this.handlingMethod.getReturnType(),
                this.handlingMethod.getGenericReturnType());

        // here we need to find types also for definition method. Definition method is in most
        // cases used for parent methods (for example for interface method of resource class). But here we
        // consider also situation when resource is a proxy (for example proxy of EJB) and definition
        // method is the original method and handling method is method on proxy. So, we try to find generic
        // type in the original class using definition method.
        final ClassTypePair definitionCtPair = ReflectionHelper.resolveGenericType(
                definitionClass,
                this.definitionMethod.getDeclaringClass(),
                this.definitionMethod.getReturnType(),
                this.definitionMethod.getGenericReturnType());
        this.rawResponseType = handlingCtPair.rawClass();
        final boolean handlerReturnTypeIsParameterized = handlingCtPair.type() instanceof ParameterizedType;
        final boolean definitionReturnTypeIsParameterized = definitionCtPair.type() instanceof ParameterizedType;
        this.responseType =
                (handlingCtPair.rawClass() == definitionCtPair.rawClass()
                        && definitionReturnTypeIsParameterized && !handlerReturnTypeIsParameterized)
                        ? definitionCtPair.type() : handlingCtPair.type();
        if (routingResponseType == null) {
            this.routingResponseType = responseType;
            this.rawRoutingResponseType = rawResponseType;
        } else {
            GenericType routingResponseGenericType = new GenericType(routingResponseType);
            this.routingResponseType = routingResponseGenericType.getType();
            this.rawRoutingResponseType = routingResponseGenericType.getRawType();
        }

        this.parameters = Collections.unmodifiableList(Parameter.create(
                handlerClass, definitionMethod.getDeclaringClass(), definitionMethod, encodedParameters));
    }

    
Get the model of the resource method handler that will be used to invoke the handling resource method on. 
Returns:resource method handler model.
/**
     * Get the model of the resource method handler that will be used to invoke
     * the {@link #getHandlingMethod() handling resource method} on.
     *
     * @return resource method handler model.
     */
    public MethodHandler getHandler() {
        return handler;
    }

    
Getter for the Java method

Returns:corresponding Java method
/**
     * Getter for the Java method
     *
     * @return corresponding Java method
     */
    public Method getHandlingMethod() {
        return handlingMethod;
    }

    
Getter for the Java method that should be executed.

Returns:corresponding Java method.
/**
     * Getter for the Java method that should be executed.
     *
     * @return corresponding Java method.
     */
    public Method getDefinitionMethod() {
        return definitionMethod;
    }

    
Get the resource method generic response type information.


The returned value provides the Type information that contains additional
generic declaration information for generic Java class types.



Returns:resource method generic response type information.
/**
     * Get the resource method generic response type information.
     * <p>
     * The returned value provides the Type information that contains additional
     * generic declaration information for generic Java class types.
     * </p>
     *
     * @return resource method generic response type information.
     */
    public Type getResponseType() {
        return responseType;
    }

    
Get the resource method raw response type.


The returned value provides information about the raw Java class.



Returns:resource method raw response type information.
/**
     * Get the resource method raw response type.
     * <p>
     * The returned value provides information about the raw Java class.
     * </p>
     *
     * @return resource method raw response type information.
     */
    public Class<?> getRawResponseType() {
        return rawResponseType;
    }

    
Check if the invocable represents an inflector
processing method. 
Returns:true, if this invocable represents an inflector invocation, false otherwise.
/**
     * Check if the invocable represents an {@link Inflector#apply(Object) inflector
     * processing method}.
     *
     * @return {@code true}, if this invocable represents an inflector invocation,
     *         {@code false} otherwise.
     */
    public boolean isInflector() {
        // Method.equals(...) does not perform the identity check (in Java SE 6)
        return APPLY_INFLECTOR_METHOD == definitionMethod || APPLY_INFLECTOR_METHOD.equals(definitionMethod);
    }

    @Override
    public boolean requiresEntity() {
        for (Parameter p : getParameters()) {
            if (Parameter.Source.ENTITY == p.getSource()) {
                return true;
            }
        }
        return false;
    }

    @Override
    public List<Parameter> getParameters() {
        return parameters;
    }

    @Override
    public void accept(ResourceModelVisitor visitor) {
        visitor.visitInvocable(this);
    }

    @Override
    public List<? extends ResourceModelComponent> getComponents() {
        return Arrays.asList(handler);
    }

    @Override
    public String toString() {
        return "Invocable{"
                + "handler=" + handler
                + ", definitionMethod=" + definitionMethod
                + ", parameters=" + parameters
                + ", responseType=" + responseType + '}';
    }

    
Get the response type of the handlingMethod that will be used during the routing for the purpose of selection of the resource method. Returned value is in most cases equal to the response type. If returned value is different then it overrides the response type for purposes of resource method selection and will be used to look for available message body writers. 
Returns:Response type used for the routing.
/**
     * Get the response type of the {@link #handlingMethod} that will be used during
     * the routing for the purpose
     * of selection of the resource method. Returned value
     * is in most cases equal to the {@link #getResponseType() response type}.
     * If returned value is different then it overrides the response type for
     * purposes of resource method selection and will be used to look for available
     * {@link javax.ws.rs.ext.MessageBodyWriter message body writers}.
     *
     * @return Response type used for the routing.
     */
    public Type getRoutingResponseType() {
        return routingResponseType;
    }

    
Get the response Class of the handlingMethod that will be used during the routing for the purpose of selection of the resource method. Returned value is in most cases equal to the response type. If returned value is different then it overrides the response type for purposes of resource method selection and will be used to look for available message body writers. 
Returns:Response type used for the routing.
/**
     * Get the response {@link Class} of the {@link #handlingMethod} that will be used during
     * the routing for the purpose
     * of selection of the resource method. Returned value
     * is in most cases equal to the {@link #getResponseType() response type}.
     * If returned value is different then it overrides the response type for
     * purposes of resource method selection and will be used to look for available
     * {@link javax.ws.rs.ext.MessageBodyWriter message body writers}.
     *
     * @return Response type used for the routing.
     */
    public Class<?> getRawRoutingResponseType() {
        return rawRoutingResponseType;
    }
}