JSONUtils.java

/*
 * (c) Copyright Reserved EVRYTHNG Limited 2016. All rights reserved.
 * Use of this material is subject to license.
 * Copying and unauthorised use of this material strictly prohibited.
 */
package com.evrythng.java.wrapper.util;

import com.evrythng.java.wrapper.exception.WrappedRuntimeException;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.deser.std.StdScalarDeserializer;
import com.fasterxml.jackson.databind.deser.std.StringDeserializer;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.util.ISO8601DateFormat;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;
import java.io.InputStream;

/**
 * JSON utilities based on Jackson {@link ObjectMapper}.
 */
public final class JSONUtils {

	/**
	 * ObjectMapper singleton.
	 */
	public static final ObjectMapper OBJECT_MAPPER = createObjectMapper();

	private JSONUtils() {
		/* Hide default constructor */
	}

	/**
	 * Deserializes the provided {@code json} {@link String} to a native {@code type} representation.
	 *
	 * @return Deserialized native instance
	 *
	 * @deprecated since 1.15
	 */
	@Deprecated
	public static <T> T read(final String json, final Class<T> type) {

		try {
			return OBJECT_MAPPER.readValue(json, type);
		} catch (Exception e) {
			// Wrap into unchecked exception:
			throw new WrappedRuntimeException(e);
		}
	}

	/**
	 * Deserializes the provided {@code json} {@link String} to a native {@code type} representation.
	 *
	 * @return Deserialized native instance
	 */
	public static <T> T read(final String json, final TypeReference<T> type) {

		try {
			return OBJECT_MAPPER.readValue(json, type);
		} catch (Exception e) {
			// Wrap into unchecked exception:
			throw new WrappedRuntimeException(e);
		}
	}

	/**
	 * Deserializes the provided {@link InputStream} to a native {@code type} representation.
	 *
	 * @return Deserialized native instance
	 *
	 * @deprecated since 1.15
	 */
	@Deprecated
	public static <T> T read(final InputStream inputStream, final TypeReference<T> type) {

		try {
			return OBJECT_MAPPER.readValue(inputStream, type);
		} catch (Exception e) {
			// Wrap into unchecked exception:
			throw new WrappedRuntimeException(e);
		}
	}

	/**
	 * Deserializes the provided {@link InputStream} to a native {@code valueType} representation.
	 *
	 * @return Deserialized native instance
	 *
	 * @deprecated since 1.15
	 */
	@Deprecated
	public static <T> T read(final InputStream inputStream, final Class<T> valueType) {

		try {
			return OBJECT_MAPPER.readValue(inputStream, valueType);
		} catch (Exception e) {
			// Wrap into unchecked exception:
			throw new WrappedRuntimeException(e);
		}
	}

	/**
	 * Converts the provided {@code object} to an JSON {@link String}.
	 */
	public static String write(final Object object) {

		try {
			return OBJECT_MAPPER.writeValueAsString(object);
		} catch (Exception e) {
			// Wrap into unchecked exception:
			throw new WrappedRuntimeException(e);
		}
	}

	/**
	 * Creates a pre-configured {@link ObjectMapper}.
	 */
	public static ObjectMapper createObjectMapper() {

		ObjectMapper mapper = new ObjectMapper();

		mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
		mapper.configure(SerializationFeature.WRITE_NULL_MAP_VALUES, false);
		mapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true);
		mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
		mapper.setDateFormat(new ISO8601DateFormat());
		
		mapper.registerModule(new CoreModule());

		return mapper;
	}

	private static class CoreModule extends SimpleModule {

		private CoreModule() {

			addDeserializer(String.class, new StdScalarDeserializer<String>(String.class) {

				private static final long serialVersionUID = 6977627268309308664L;
				private final StringDeserializer STRING_DESERIALIZER = new StringDeserializer();

				@Override
				public String deserialize(final JsonParser jp, final DeserializationContext ctx) throws IOException {

					return StringUtils.trim(STRING_DESERIALIZER.deserialize(jp, ctx));
				}
			});
		}
	}
}