001/*
002 * (C) Copyright 2015 Nuxeo SA (http://nuxeo.com/) and contributors.
003 *
004 * All rights reserved. This program and the accompanying materials
005 * are made available under the terms of the GNU Lesser General Public License
006 * (LGPL) version 2.1 which accompanies this distribution, and is available at
007 * http://www.gnu.org/licenses/lgpl-2.1.html
008 *
009 * This library is distributed in the hope that it will be useful,
010 * but WITHOUT ANY WARRANTY; without even the implied warranty of
011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 * Lesser General Public License for more details.
013 *
014 * Contributors:
015 *     Nicolas Chapurlat <nchapurlat@nuxeo.com>
016 */
017
018package org.nuxeo.ecm.core.io.registry;
019
020import static javax.ws.rs.core.MediaType.APPLICATION_JSON_TYPE;
021
022import java.io.ByteArrayInputStream;
023import java.io.ByteArrayOutputStream;
024import java.io.IOException;
025import java.lang.reflect.Type;
026import java.util.List;
027
028import org.apache.commons.lang3.reflect.TypeUtils;
029import org.nuxeo.ecm.core.io.registry.context.RenderingContext;
030import org.nuxeo.ecm.core.io.registry.context.RenderingContext.CtxBuilder;
031import org.nuxeo.runtime.api.Framework;
032
033/**
034 * Quick use of {@link MarshallerRegistry}.
035 *
036 * @since 7.2
037 */
038public final class MarshallerHelper {
039
040    /**
041     * Just call static methods.
042     */
043    private MarshallerHelper() {
044    }
045
046    private static MarshallerRegistry getService() {
047        MarshallerRegistry registry = Framework.getService(MarshallerRegistry.class);
048        return registry;
049    }
050
051    /**
052     * Checks the marshallers isn't null. Throw an exception if it is.
053     */
054    private static void checkMarshaller(Type type, Marshaller<?> marshaller) {
055        if (marshaller == null) {
056            throw new MarshallingException("No marshaller found for type " + type.toString());
057        }
058    }
059
060    /**
061     * Convert the given object to json.
062     *
063     * @param object The object to convert as json.
064     * @param ctx May be null - otherwise, use {@link CtxBuilder} to create the context.
065     * @return the resulting json.
066     * @since 7.2
067     */
068    public static <T> String objectToJson(T object, RenderingContext ctx) throws IOException {
069        @SuppressWarnings("unchecked")
070        Class<T> type = (Class<T>) object.getClass();
071        Writer<T> writer = getService().getWriter(ctx, type, APPLICATION_JSON_TYPE);
072        checkMarshaller(type, writer);
073        ByteArrayOutputStream baos = new ByteArrayOutputStream();
074        writer.write(object, type, type, APPLICATION_JSON_TYPE, baos);
075        return baos.toString();
076    }
077
078    /**
079     * Convert the given object to json.
080     * <p>
081     * Specify its generic type to be sure to get the best marshaller to manage it.
082     * </p>
083     *
084     * @param genericType The generic type of the object. You can easily create parametrize type using
085     *            {@link TypeUtils#parameterize(Class, Type...)}
086     * @param object The object to convert as json.
087     * @param ctx May be null - otherwise, use {@link CtxBuilder} to create the context.
088     * @return the resulting json.
089     * @since 7.2
090     */
091    public static <T> String objectToJson(Type genericType, T object, RenderingContext ctx) throws IOException {
092        @SuppressWarnings("unchecked")
093        Class<T> type = (Class<T>) object.getClass();
094        Writer<T> writer = getService().getWriter(ctx, type, genericType, APPLICATION_JSON_TYPE);
095        checkMarshaller(genericType, writer);
096        ByteArrayOutputStream baos = new ByteArrayOutputStream();
097        writer.write(object, type, genericType, APPLICATION_JSON_TYPE, baos);
098        return baos.toString();
099    }
100
101    /**
102     * Convert the given list to json.
103     * <p>
104     * Specify the list element type to get the best marshaller to manage conversion.
105     * </p>
106     *
107     * @param elementType The element type of the list.
108     * @param list The list to convert.
109     * @param ctx May be null - otherwise, use {@link CtxBuilder} to create the context.
110     * @return the resulting json.
111     * @since 7.2
112     */
113    public static <T> String listToJson(Class<T> elementType, List<T> list, RenderingContext ctx) throws IOException {
114        Type genericType = TypeUtils.parameterize(List.class, elementType);
115        @SuppressWarnings("rawtypes")
116        Writer<List> writer = getService().getWriter(ctx, List.class, genericType, APPLICATION_JSON_TYPE);
117        checkMarshaller(genericType, writer);
118        ByteArrayOutputStream baos = new ByteArrayOutputStream();
119        writer.write(list, List.class, genericType, APPLICATION_JSON_TYPE, baos);
120        return baos.toString();
121    }
122
123    /**
124     * Read an object of the given type from given json.
125     *
126     * @param type The type of the read object.
127     * @param json The json to parse.
128     * @param ctx May be null - otherwise, use {@link CtxBuilder} to create the context.
129     * @return the resulting object.
130     * @since 7.2
131     */
132    public static <T> T objectToJson(Class<T> type, String json, RenderingContext ctx) throws IOException {
133        Reader<T> reader = getService().getReader(ctx, type, APPLICATION_JSON_TYPE);
134        checkMarshaller(type, reader);
135        return reader.read(type, type, APPLICATION_JSON_TYPE, new ByteArrayInputStream(json.getBytes()));
136    }
137
138    /**
139     * Read an object of the given type from given json.
140     * <p>
141     * Specify its generic type to be sure to get the best marshaller to manage it.
142     * </p>
143     *
144     * @param type The type of the read object.
145     * @param genericType The generic type of the object. You can easily create parametrize type using
146     *            {@link TypeUtils#parameterize(Class, Type...)}
147     * @param json The json to parse.
148     * @param ctx May be null - otherwise, use {@link CtxBuilder} to create the context.
149     * @return the resulting object.
150     * @since 7.2
151     */
152    public static <T> T objectToJson(Class<T> type, Type genericType, String json, RenderingContext ctx)
153            throws IOException {
154        Reader<T> reader = getService().getReader(ctx, type, genericType, APPLICATION_JSON_TYPE);
155        checkMarshaller(genericType, reader);
156        return reader.read(type, genericType, APPLICATION_JSON_TYPE, new ByteArrayInputStream(json.getBytes()));
157    }
158
159    /**
160     * Read an object of the given type from given json.
161     * <p>
162     * Specify the list element type to get the best marshaller to manage conversion.
163     * </p>
164     *
165     * @param elementType The element type of the list.
166     * @param json The json to parse.
167     * @param ctx May be null - otherwise, use {@link CtxBuilder} to create the context.
168     * @return the resulting list.
169     * @since 7.2
170     */
171    @SuppressWarnings("unchecked")
172    public static <T> List<T> listToJson(Class<T> elementType, String json, RenderingContext ctx) throws IOException {
173        Type genericType = TypeUtils.parameterize(List.class, elementType);
174        @SuppressWarnings("rawtypes")
175        Reader<List> reader = getService().getReader(ctx, List.class, genericType, APPLICATION_JSON_TYPE);
176        checkMarshaller(genericType, reader);
177        return reader.read(List.class, genericType, APPLICATION_JSON_TYPE, new ByteArrayInputStream(json.getBytes()));
178    }
179
180}