org.apache.hadoop.registry.client.binding.JsonSerDeser.java Source code

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Here is the source code for org.apache.hadoop.registry.client.binding.JsonSerDeser.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.hadoop.registry.client.binding;

import com.fasterxml.jackson.core.JsonProcessingException;
import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.registry.client.exceptions.InvalidRecordException;
import org.apache.hadoop.registry.client.exceptions.NoRecordException;
import org.apache.hadoop.util.JsonSerialization;

import java.io.EOFException;
import java.io.IOException;

/**
 * Support for marshalling objects to and from JSON.
 *  <p>
 * This extends {@link JsonSerialization} with the notion
 * of a marker field in the JSON file, with
 * <ol>
 *   <li>a fail-fast check for it before even trying to parse.</li>
 *   <li>Specific IOException subclasses for a failure.</li>
 * </ol>
 * The rationale for this is not only to support different things in the,
 * registry, but the fact that all ZK nodes have a size &gt; 0 when examined.
 *
 * @param <T> Type to marshal.
 */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class JsonSerDeser<T> extends JsonSerialization<T> {

    private static final String UTF_8 = "UTF-8";
    public static final String E_NO_DATA = "No data at path";
    public static final String E_DATA_TOO_SHORT = "Data at path too short";
    public static final String E_MISSING_MARKER_STRING = "Missing marker string: ";

    /**
     * Create an instance bound to a specific type
     * @param classType class to marshall
     */
    public JsonSerDeser(Class<T> classType) {
        super(classType, false, false);
    }

    /**
     * Deserialize from a byte array
     * @param path path the data came from
     * @param bytes byte array
     * @throws IOException all problems
     * @throws EOFException not enough data
     * @throws InvalidRecordException if the parsing failed -the record is invalid
     * @throws NoRecordException if the data is not considered a record: either
     * it is too short or it did not contain the marker string.
     */
    public T fromBytes(String path, byte[] bytes) throws IOException {
        return fromBytes(path, bytes, "");
    }

    /**
     * Deserialize from a byte array, optionally checking for a marker string.
     * <p>
     * If the marker parameter is supplied (and not empty), then its presence
     * will be verified before the JSON parsing takes place; it is a fast-fail
     * check. If not found, an {@link InvalidRecordException} exception will be
     * raised
     * @param path path the data came from
     * @param bytes byte array
     * @param marker an optional string which, if set, MUST be present in the
     * UTF-8 parsed payload.
     * @return The parsed record
     * @throws IOException all problems
     * @throws EOFException not enough data
     * @throws InvalidRecordException if the JSON parsing failed.
     * @throws NoRecordException if the data is not considered a record: either
     * it is too short or it did not contain the marker string.
     */
    public T fromBytes(String path, byte[] bytes, String marker) throws IOException {
        int len = bytes.length;
        if (len == 0) {
            throw new NoRecordException(path, E_NO_DATA);
        }
        if (StringUtils.isNotEmpty(marker) && len < marker.length()) {
            throw new NoRecordException(path, E_DATA_TOO_SHORT);
        }
        String json = new String(bytes, 0, len, UTF_8);
        if (StringUtils.isNotEmpty(marker) && !json.contains(marker)) {
            throw new NoRecordException(path, E_MISSING_MARKER_STRING + marker);
        }
        try {
            return fromJson(json);
        } catch (JsonProcessingException e) {
            throw new InvalidRecordException(path, e.toString(), e);
        }
    }

}