JsonQualifierAndValueRowSerializer.java

/*
 * 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.nifi.hbase.io;

import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.nifi.hbase.scan.ResultCell;
import org.apache.nifi.hbase.util.RowSerializerUtil;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.Charset;

/**
 * Serializes an HBase row to a JSON document of the form:
 *
 * {
 *   "qual1" : "val1",
 *   "qual2" : "val2"
 * }
 *
 * If base64encode is true, the qualifiers and values will be represented as base 64 encoded strings.
 */
public class JsonQualifierAndValueRowSerializer implements RowSerializer {

    private final Charset decodeCharset;
    private final Charset encodeCharset;
    private final boolean base64encode;

    public JsonQualifierAndValueRowSerializer(final Charset decodeCharset, final Charset encodeCharset) {
        this(decodeCharset, encodeCharset, false);
    }

    public JsonQualifierAndValueRowSerializer(final Charset decodeCharset, final Charset encodeCharset, final boolean base64encode) {
        this.decodeCharset = decodeCharset;
        this.encodeCharset = encodeCharset;
        this.base64encode = base64encode;
    }

    @Override
    public String serialize(byte[] rowKey, ResultCell[] cells) {
        final StringBuilder jsonBuilder = new StringBuilder();
        jsonBuilder.append("{");

        int i = 0;
        for (final ResultCell cell : cells) {
            final String cellQualifier = RowSerializerUtil.getCellQualifier(cell, decodeCharset, base64encode);
            final String cellValue = RowSerializerUtil.getCellValue(cell, decodeCharset, base64encode);

            if (i > 0) {
                jsonBuilder.append(", ");
            }

            appendString(jsonBuilder, cellQualifier, base64encode);
            jsonBuilder.append(":");
            appendString(jsonBuilder, cellValue, base64encode);

            i++;
        }

        jsonBuilder.append("}");
        return jsonBuilder.toString();
    }

    @Override
    public void serialize(final byte[] rowKey, final ResultCell[] cells, final OutputStream out) throws IOException {
        final String json = serialize(rowKey, cells);
        out.write(json.getBytes(encodeCharset));
    }

    private void appendString(final StringBuilder jsonBuilder, final String str, final boolean base64encode) {
        jsonBuilder.append("\"");

        // only escape the value when not doing base64
        if (!base64encode) {
            jsonBuilder.append(StringEscapeUtils.escapeJson(str));
        } else {
            jsonBuilder.append(str);
        }

        jsonBuilder.append("\"");
    }


}