io.thekraken.json2hive.Json.java Source code

Introduction

Here is the source code for io.thekraken.json2hive.Json.java

Source

/*******************************************************************************
 * Copyright 2014 Anthony Corbacho and contributors.
 *
 * 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 io.thekraken.json2hive;

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

import java.util.Map.Entry;

/**
 * Generates Hive schemas for use with the JSON SerDe from
 * com.cloudera.hive.serde.JSONSerDe (but can be change in the create method {@link #create(String, String, Boolean, String)})<p/>
 *
 * Pass in a valid JSON document string to {@link #create(String, String)} and it will
 * return a Hive schema for the JSON sample.<p/>
 *
 * It supports embedded JSON objects, arrays and the standard JSON scalar types: strings,
 * numbers, booleans and null.<p/>
 * You probably don't want null in the JSON document you provide
 * as Hive can't use that.<p/>
 *
 * This program uses the JSON parsing code from Gson and that code is included in this
 * library {@see build.gradle}.<p/>
 *
 * @author anthonycorbacho
 * @since 0.0.1
 */
public class Json {

    /**
     * Pass in any valid JSON object and a Hive schema will be returned for it.
     * You should avoid having null values in the JSON document, however.
     *
     * @param hiveTableName
     * @param jsonObject
     * @return hive table schema
     * @throws Exception
     * @throws JsonSyntaxException
     */
    public static String create(String hiveTableName, String jsonObject) {
        return createHiveTable(hiveTableName, jsonObject).getSchema();
    }

    /**
     * Pass in any valid JSON object and a Hive schema will be returned for it.
     * You should avoid having null values in the JSON document, however.
     *
     * @param hiveTableName
     * @param jsonObject
     * @param withSerde : True if you want to incluse SERDE
     * @param serde : Override serde classname (default: {@code com.cloudera.hive.serde.JSONSerDe})
     *
     * @return hive table schema
     * @throws Exception
     * @throws JsonSyntaxException
     */
    public static String create(String hiveTableName, String jsonObject, Boolean withSerde, String serde) {
        HiveTable hive = createHiveTable(hiveTableName, jsonObject);
        if (withSerde) {
            if (serde != null) {
                hive.addJsonSerde(serde);
            } else {
                hive.addJsonSerde();
            }
        }
        return hive.getSchema();
    }

    private static HiveTable createHiveTable(String hiveTableName, String jsonObject) {
        HiveTable hive = new HiveTable(hiveTableName);

        JsonParser parser = new JsonParser();
        JsonElement jsonElement = parser.parse(jsonObject);
        JsonObject jsonObj = jsonElement.getAsJsonObject();

        for (Entry<String, JsonElement> entry : jsonObj.entrySet()) {
            String key = entry.getKey();
            JsonElement value = entry.getValue();

            /** Structure */
            if (value.isJsonObject()) {
                hive.addStructure(key, value.toString());
            }
            /** Array */
            else if (value.isJsonArray()) {
                hive.addArray(key, value.toString());
            } else {
                /** primitive */
                if (value.isJsonNull()) {
                    hive.AddUnknow(value.toString());
                } else {
                    hive.addPrimitive(key, value.toString());
                }
            }
        }
        hive.close();
        return hive;
    }

}