com.cloudera.cdk.morphline.json.ReadJsonBuilder.java Source code

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Here is the source code for com.cloudera.cdk.morphline.json.ReadJsonBuilder.java

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/*
 * Copyright 2013 Cloudera 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 com.cloudera.cdk.morphline.json;

import java.io.IOException;
import java.io.InputStream;
import java.util.Collection;
import java.util.Collections;

import com.cloudera.cdk.morphline.api.Command;
import com.cloudera.cdk.morphline.api.CommandBuilder;
import com.cloudera.cdk.morphline.api.MorphlineCompilationException;
import com.cloudera.cdk.morphline.api.MorphlineContext;
import com.cloudera.cdk.morphline.api.Record;
import com.cloudera.cdk.morphline.base.Fields;
import com.cloudera.cdk.morphline.stdio.AbstractParser;
import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.MappingIterator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.typesafe.config.Config;

/**
 * Command that parses an InputStream that contains JSON data; for each JSON object in the stream,
 * the command emits a morphline record containing the object as an attachment in
 * {@link Fields#ATTACHMENT_BODY}.
 */
public final class ReadJsonBuilder implements CommandBuilder {

    /** The MIME type identifier that will be filled into output records */
    public static final String MIME_TYPE = "json/java+memory";

    @Override
    public Collection<String> getNames() {
        return Collections.singletonList("readJson");
    }

    @Override
    public Command build(Config config, Command parent, Command child, MorphlineContext context) {
        return new ReadJson(config, parent, child, context);
    }

    ///////////////////////////////////////////////////////////////////////////////
    // Nested classes:
    ///////////////////////////////////////////////////////////////////////////////
    private static final class ReadJson extends AbstractParser {

        private final ObjectReader reader;

        public ReadJson(Config config, Command parent, Command child, MorphlineContext context) {
            super(config, parent, child, context);

            JsonFactory jsonFactory = null;
            String jsonFactoryClassName = getConfigs().getString(config, "jsonFactory", null);
            if (jsonFactoryClassName != null) {
                try {
                    jsonFactory = (JsonFactory) Class.forName(jsonFactoryClassName).newInstance();
                } catch (Exception e) {
                    throw new MorphlineCompilationException("Cannot create instance", config, e);
                }
            }

            String objectMapperClassName = getConfigs().getString(config, "objectMapper", null);
            ObjectMapper objectMapper = null;
            if (objectMapperClassName != null) {
                try {
                    objectMapper = (ObjectMapper) Class.forName(objectMapperClassName).newInstance();
                } catch (Exception e) {
                    throw new MorphlineCompilationException("Cannot create instance", config, e);
                }
            } else {
                objectMapper = new ObjectMapper(jsonFactory);
            }

            String outputClassName = getConfigs().getString(config, "outputClass", JsonNode.class.getName());
            Class outputClass;
            try {
                outputClass = Class.forName(outputClassName);
            } catch (ClassNotFoundException e) {
                throw new MorphlineCompilationException("Class not found", config, e);
            }

            reader = objectMapper.reader(outputClass);
            validateArguments();
        }

        @Override
        protected boolean doProcess(Record inputRecord, InputStream in) throws IOException {
            MappingIterator iter = reader.readValues(in);
            try {
                while (iter.hasNextValue()) {
                    Object rootNode = iter.nextValue();
                    incrementNumRecords();
                    LOG.debug("jsonObject: {}", rootNode);

                    Record outputRecord = inputRecord.copy();
                    removeAttachments(outputRecord);
                    outputRecord.put(Fields.ATTACHMENT_BODY, rootNode);
                    outputRecord.put(Fields.ATTACHMENT_MIME_TYPE, MIME_TYPE);

                    // pass record to next command in chain:
                    if (!getChild().process(outputRecord)) {
                        return false;
                    }
                }
                return true;
            } finally {
                iter.close();
            }
        }
    }
}