com.facebook.presto.kinesis.decoder.json.JsonKinesisRowDecoder.java Source code

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Here is the source code for com.facebook.presto.kinesis.decoder.json.JsonKinesisRowDecoder.java

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/*
 * 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.facebook.presto.kinesis.decoder.json;

import static com.google.common.base.Preconditions.checkState;

import java.util.List;
import java.util.Map;
import java.util.Set;

import com.facebook.presto.kinesis.KinesisColumnHandle;
import com.facebook.presto.kinesis.KinesisFieldValueProvider;
import com.facebook.presto.kinesis.decoder.KinesisFieldDecoder;
import com.facebook.presto.kinesis.decoder.KinesisRowDecoder;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.MissingNode;
import com.google.common.base.Splitter;
import com.google.inject.Inject;

public class JsonKinesisRowDecoder implements KinesisRowDecoder {
    public static final String NAME = "json";

    private final ObjectMapper objectMapper;

    @Inject
    public JsonKinesisRowDecoder(ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    @Override
    public String getName() {
        return NAME;
    }

    @Override
    public boolean decodeRow(byte[] data, Set<KinesisFieldValueProvider> fieldValueProviders,
            List<KinesisColumnHandle> columnHandles,
            Map<KinesisColumnHandle, KinesisFieldDecoder<?>> fieldDecoders) {
        JsonNode tree;

        try {
            tree = objectMapper.readTree(data);
        } catch (Exception e) {
            return false;
        }

        for (KinesisColumnHandle columnHandle : columnHandles) {
            if (columnHandle.isInternal()) {
                continue;
            }
            @SuppressWarnings("unchecked")
            KinesisFieldDecoder<JsonNode> decoder = (KinesisFieldDecoder<JsonNode>) fieldDecoders.get(columnHandle);

            if (decoder != null) {
                JsonNode node = locateNode(tree, columnHandle);
                fieldValueProviders.add(decoder.decode(node, columnHandle));
            }
        }
        return true;
    }

    private static JsonNode locateNode(JsonNode tree, KinesisColumnHandle columnHandle) {
        String mapping = columnHandle.getMapping();
        checkState(mapping != null, "No mapping for %s", columnHandle.getName());

        JsonNode currentNode = tree;
        for (String pathElement : Splitter.on('/').omitEmptyStrings().split(mapping)) {
            String baseName = pathElement;
            int index = -1;
            if (pathElement.contains("[")) {
                String[] splits = pathElement.split("[\\[\\]]");
                if (splits.length == 2) {
                    if (splits[1].matches("[0-9]+")) {
                        index = Integer.parseInt(splits[1]);
                    }
                }
                baseName = splits[0];
            }

            if (!currentNode.has(baseName)) {
                return MissingNode.getInstance();
            }

            currentNode = currentNode.path(baseName);
            if (index >= 0 && currentNode.isArray()) {
                currentNode = currentNode.get(index);

                // From Jackson docs: If index is less than 0, or equal-or-greater than node.size(), null is returned;
                // no exception is thrown for any index.
                if (currentNode == null) {
                    return MissingNode.getInstance();
                } else if (currentNode.isMissingNode() || currentNode.isNull()) {
                    return currentNode; // don't continue
                }
            }
        }
        return currentNode;
    }
}