001/*
002 * (C) Copyright 2006-2010 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     bstefanescu
018 */
019package org.nuxeo.ecm.automation.io.services.codec;
020
021import java.io.IOException;
022import java.lang.reflect.ParameterizedType;
023import java.lang.reflect.Type;
024
025import org.nuxeo.ecm.core.api.CoreSession;
026
027import com.fasterxml.jackson.core.JsonGenerator;
028import com.fasterxml.jackson.core.JsonParser;
029import com.fasterxml.jackson.databind.ObjectMapper;
030
031/**
032 * @author <a href="mailto:[email protected]">Bogdan Stefanescu</a>
033 */
034public abstract class ObjectCodec<T> {
035
036    public static Class<?> findParametrizedType(Class<?> clazz) {
037        Type superclass = clazz.getGenericSuperclass();
038        while (superclass instanceof Class<?>) {
039            superclass = ((Class<?>) superclass).getGenericSuperclass();
040        }
041        if (superclass == null) {
042            throw new RuntimeException("Missing type parameter.");
043        }
044        Type type = ((ParameterizedType) superclass).getActualTypeArguments()[0];
045        if (!(type instanceof Class<?>)) {
046            throw new RuntimeException("Invalid class parameter type. " + type);
047        }
048        return (Class<?>) type;
049    }
050
051    protected Class<T> type;
052
053    @SuppressWarnings("unchecked")
054    public ObjectCodec() {
055        this.type = (Class<T>) findParametrizedType(getClass());
056    }
057
058    public ObjectCodec(Class<T> type) {
059        this.type = type;
060    }
061
062    /**
063     * Get this codec type. Implementors can override to return a short name. The default name is the object type name.
064     *
065     * @return
066     */
067    public String getType() {
068        return type.getName();
069    }
070
071    /**
072     * Whether this codec is a builtin codec
073     *
074     * @return
075     */
076    public boolean isBuiltin() {
077        return false;
078    }
079
080    public Class<T> getJavaType() {
081        return type;
082    }
083
084    public void write(JsonGenerator jg, T value) throws IOException {
085        if (jg.getCodec() == null) {
086            jg.setCodec(new ObjectMapper());
087        }
088        jg.writeObject(value);
089    }
090
091    /**
092     * When the object codec is called the stream is positioned on the first value. For inlined objects this is the
093     * first value after the "entity-type" property. For non inlined objects this will be the object itself (i.e. '{' or
094     * '[')
095     *
096     * @param jp
097     * @return
098     * @throws IOException
099     */
100    public T read(JsonParser jp, CoreSession session) throws IOException {
101        if (jp.getCodec() == null) {
102            jp.setCodec(new ObjectMapper());
103        }
104        return jp.readValueAs(type);
105    }
106
107}