JacksonMessageBodyProvider.java

/**
 * Copyright 2014 Confluent Inc.
 *
 * 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 io.confluent.rest.validation;

import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException;
import com.fasterxml.jackson.jaxrs.json.JacksonJaxbJsonProvider;

import javax.validation.ConstraintViolationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;

import java.io.IOException;
import java.io.InputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

/**
 * Jackson provider that handles some additional exceptions. This allows additional processing and
 * validation of entities during parsing that don't fit well with the standard validation framework
 * (e.g. decoding of encoded fields to avoid storing the original and repeated decoding if the field
 * is accessed multiple times).
 */
@Provider
public class JacksonMessageBodyProvider extends JacksonJaxbJsonProvider {

  public JacksonMessageBodyProvider() {
    setMapper(new ObjectMapper());
  }

  public JacksonMessageBodyProvider(ObjectMapper mapper) {
    setMapper(mapper);
  }

  @Override
  protected boolean hasMatchingMediaType(MediaType mediaType) {
    return super.hasMatchingMediaType(mediaType)
           || isApplicationOctetStream(mediaType);
  }

  protected boolean isApplicationOctetStream(MediaType mediaType) {
    return mediaType != null
           && mediaType.getType().equals("application")
           && mediaType.getSubtype().equals("octet-stream");
  }

  @Override
  public Object readFrom(Class<Object> type,
                         Type genericType,
                         Annotation[] annotations,
                         MediaType mediaType,
                         MultivaluedMap<String, String> httpHeaders,
                         InputStream entityStream) throws IOException {
    try {
      return super.readFrom(type, genericType, annotations, mediaType, httpHeaders, entityStream);
    } catch (UnrecognizedPropertyException e) {
      throw ConstraintViolations.simpleException("Unrecognized field: " + e.getPropertyName());
    } catch (JsonMappingException e) {
      // This needs to handle 2 JSON parsing error cases. Normally you would expect to see a
      // JsonMappingException because the data couldn't be parsed, but it can also occur when the
      // raw JSON is valid and satisfies the validation constraint annotations, but an exception is
      // thrown by the entity during construction. In the former case, we want to return a 400
      // (Bad Request), in the latter a 422 (Unprocessable Entity) with a useful error message. We
      // don't want to expose just any exception message via the API, so this code specifically
      // detects ConstraintViolationExceptions that were thrown *after* the normal validation
      // checks, i.e. when the entity Java object was being constructed.
      Throwable cause = e.getCause();
      if (cause instanceof ConstraintViolationException) {
        throw (ConstraintViolationException) cause;
      }
      throw e;
    }
  }
}