BodyParserJson.java

/*
 * #%L
 * Wisdom-Framework
 * %%
 * Copyright (C) 2013 - 2014 Wisdom Framework
 * %%
 * 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.
 * #L%
 */
package org.wisdom.content.bodyparsers;

import com.google.common.collect.ImmutableList;
import org.apache.felix.ipojo.annotations.Component;
import org.apache.felix.ipojo.annotations.Instantiate;
import org.apache.felix.ipojo.annotations.Provides;
import org.apache.felix.ipojo.annotations.Requires;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.wisdom.api.content.BodyParser;
import org.wisdom.api.content.Json;
import org.wisdom.api.http.Context;
import org.wisdom.api.http.MimeTypes;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.List;

/**
 * The component responsible of parsing JSON payload to build objects.
 */
@Component
@Provides
@Instantiate
public class BodyParserJson implements BodyParser {

    @Requires
    Json json;

    private static final String ERROR = "Error parsing incoming Json";

    private static final Logger LOGGER = LoggerFactory.getLogger(BodyParserJson.class);

    /**
     * Builds an instance of {@literal T} from the request payload.
     *
     * @param context  The context
     * @param classOfT The class we expect
     * @param <T>      the type of the object
     * @return the build object, {@literal null} if the object cannot be built.
     */
    public <T> T invoke(Context context, Class<T> classOfT) {
        return invoke(context, classOfT, null);
    }

    /**
     * Builds an instance of {@literal T} from the request payload.
     *
     * @param context  The context
     * @param classOfT The class we expect
     * @param <T>      the type of the object
     * @return the build object, {@literal null} if the object cannot be built.
     */
    public <T> T invoke(Context context, Class<T> classOfT, Type genericType) {
        T t = null;
        try {
            final String content = context.body();
            if (content == null || content.length() == 0) {
                return null;
            }
            if (genericType != null) {
                t = json.mapper().readValue(content,
                        json.mapper().constructType(genericType));
            } else {
                t = json.mapper().readValue(content, classOfT);
            }
        } catch (IOException e) {
            LOGGER.error(ERROR, e);
        }

        return t;
    }


    /**
     * Builds an instance of {@literal T} from the request payload.
     *
     * @param bytes    the payload.
     * @param classOfT The class we expect
     * @param <T>      the type of the object
     * @return the build object, {@literal null} if the object cannot be built.
     */
    @Override
    public <T> T invoke(byte[] bytes, Class<T> classOfT) {
        T t = null;
        try {
            t = json.mapper().readValue(bytes, classOfT);
        } catch (IOException e) {
            LOGGER.error(ERROR, e);
        }

        return t;
    }

    /**
     * @return the singleton list containing "application/json".
     */
    public List<String> getContentTypes() {
        return ImmutableList.of(MimeTypes.JSON);
    }

}