/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.http.codec.json;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import com.fasterxml.jackson.annotation.JsonView;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.type.TypeFactory;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.core.ResolvableType;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
import org.springframework.util.ObjectUtils;
/**
* Base class providing support methods for Jackson 2.9 encoding and decoding.
*
* @author Sebastien Deleuze
* @author Rossen Stoyanchev
* @since 5.0
*/
public abstract class Jackson2CodecSupport {
/**
* The key for the hint to specify a "JSON View" for encoding or decoding
* with the value expected to be a {@link Class}.
* @see <a href="http://wiki.fasterxml.com/JacksonJsonViews">Jackson JSON Views</a>
*/
public static final String JSON_VIEW_HINT = Jackson2CodecSupport.class.getName() + ".jsonView";
private static final String JSON_VIEW_HINT_ERROR =
"@JsonView only supported for write hints with exactly 1 class argument: ";
protected static final List<MimeType> JSON_MIME_TYPES = Arrays.asList(
new MimeType("application", "json", StandardCharsets.UTF_8),
new MimeType("application", "*+json", StandardCharsets.UTF_8));
protected final ObjectMapper objectMapper;
private final List<MimeType> mimeTypes;
/**
* Constructor with a Jackson {@link ObjectMapper} to use.
*/
protected Jackson2CodecSupport(ObjectMapper objectMapper, MimeType... mimeTypes) {
Assert.notNull(objectMapper, "ObjectMapper must not be null");
this.objectMapper = objectMapper;
this.mimeTypes = !ObjectUtils.isEmpty(mimeTypes) ? Arrays.asList(mimeTypes) : JSON_MIME_TYPES;
}
protected boolean supportsMimeType(MimeType mimeType) {
return (mimeType == null || this.mimeTypes.stream().anyMatch(m -> m.isCompatibleWith(mimeType)));
}
protected JavaType getJavaType(Type type, Class<?> contextClass) {
TypeFactory typeFactory = this.objectMapper.getTypeFactory();
return typeFactory.constructType(GenericTypeResolver.resolveType(type, contextClass));
}
protected Map<String, Object> getHints(ResolvableType actualType) {
return getParameter(actualType)
.flatMap(parameter -> Optional.ofNullable(getAnnotation(parameter, JsonView.class))
.map(annotation -> {
Class<?>[] classes = annotation.value();
Assert.isTrue(classes.length == 1, JSON_VIEW_HINT_ERROR + parameter);
return Collections.<String, Object>singletonMap(JSON_VIEW_HINT, classes[0]);
}))
.orElse(Collections.emptyMap());
}
protected Optional<MethodParameter> getParameter(ResolvableType type) {
return Optional.ofNullable(type.getSource() instanceof MethodParameter ?
(MethodParameter) type.getSource() : null);
}
protected abstract <A extends Annotation> A getAnnotation(MethodParameter parameter, Class<A> annotType);
}