tv.arte.resteventapi.core.presentation.decoration.RestEventApiAnnotationMappingDiscoverer.java Source code

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Here is the source code for tv.arte.resteventapi.core.presentation.decoration.RestEventApiAnnotationMappingDiscoverer.java

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package tv.arte.resteventapi.core.presentation.decoration;

/*
 * #%L
 * RestEventAPI
 * %%
 * Copyright (C) 2014 ARTE G.E.I.E
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of The MIT License (MIT) as published by the Open Source 
 * Initiative.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See The 
 * MIT License (MIT) for more details.
 * 
 * You should have received a copy of The MIT License (MIT) 
 * along with this program.  If not, see <http://opensource.org/licenses/MIT>
 * #L%
 */

import static org.springframework.core.annotation.AnnotationUtils.findAnnotation;
import static org.springframework.core.annotation.AnnotationUtils.getValue;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;

import org.springframework.hateoas.core.AnnotationMappingDiscoverer;
import org.springframework.hateoas.core.MappingDiscoverer;
import org.springframework.util.Assert;

/*
 * Code particialy copied from string-hateoas project 
 */

/**
 * Helper to discover an annotation a class
 * 
 * @author Oliver Gierke
 * @author Kamill Sokol
 * @author Simeon Petev
 */
public class RestEventApiAnnotationMappingDiscoverer implements MappingDiscoverer {

    private final Class<? extends Annotation> annotationType;
    private final String mappingAttributeName;

    /**
     * Creates an {@link AnnotationMappingDiscoverer} for the given annotation type. Will lookup the {@code value}
     * attribute by default.
     * 
     * @param annotation must not be {@literal null}.
     */
    public RestEventApiAnnotationMappingDiscoverer(Class<? extends Annotation> annotation) {
        this(annotation, null);
    }

    /**
     * Creates an {@link AnnotationMappingDiscoverer} for the given annotation type and attribute name.
     * 
     * @param annotation must not be {@literal null}.
     * @param mappingAttributeName if {@literal null}, it defaults to {@code value}.
     */
    public RestEventApiAnnotationMappingDiscoverer(Class<? extends Annotation> annotation,
            String mappingAttributeName) {

        Assert.notNull(annotation);

        this.annotationType = annotation;
        this.mappingAttributeName = mappingAttributeName;
    }

    public String getMapping(Class<?> type) {

        Assert.notNull(type, "Type must not be null!");

        String[] mapping = getMappingFrom(findAnnotation(type, annotationType));

        return mapping.length == 0 ? null : mapping[0];
    }

    public String getMapping(Method method) {

        Assert.notNull(method, "Method must not be null!");
        return getMapping(method.getDeclaringClass(), method);
    }

    public String getMapping(Class<?> type, Method method) {

        Assert.notNull(type, "Type must not be null!");
        Assert.notNull(method, "Method must not be null!");

        String[] mapping = getMappingFrom(findAnnotation(method, annotationType));

        String typeMapping = getMapping(type);

        if (mapping == null || mapping.length == 0) {
            return typeMapping;
        }

        return typeMapping == null || "/".equals(typeMapping) ? mapping[0] : typeMapping + mapping[0];
    }

    private String[] getMappingFrom(Annotation annotation) {

        Object value = mappingAttributeName == null ? getValue(annotation)
                : getValue(annotation, mappingAttributeName);

        if (value instanceof String) {
            return new String[] { (String) value };
        } else if (value instanceof String[]) {
            return (String[]) value;
        } else if (value == null) {
            return new String[0];
        }

        throw new IllegalStateException(
                String.format("Unsupported type for the mapping attribute! Support String and String[] but got %s!",
                        value.getClass()));
    }
}