獲取 Parquet檔案，解析為LIst<String>

package com.emcc.hiacloud.analytics.common.util;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.hadoop.fs.Path;
import org.apache.parquet.avro.AvroParquetReader;
import org.apache.parquet.hadoop.ParquetReader;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class ParquetUtils {
    private static final String csvDelimiter = ",";
    public static Map<String,List<String[]>> viewParquet(String path,int maxLine) throws IOException {
        Map<String,List<String[]>> parquetInfo=new HashMap<>();
        List<String[]> dataList=new ArrayList<>();
        Schema.Field[] fields = null;
        String[] fieldNames = new String[0];
        try (
             ParquetReader<GenericData.Record> reader =
             AvroParquetReader.<GenericData.Record>builder(new Path(path)).build()
        ){
           int  x=0;
            GenericData.Record record;
            //解析Parquet資料逐行讀取
            while ((record = reader.read()) != null && x<maxLine) {
                //讀取第一行獲取列頭資訊
                if (fields == null) {
                    final List<Schema.Field> fieldsList = record.getSchema().getFields();
                    fieldNames = getFieldNames(fields = fieldsList.toArray(new Schema.Field[0]));
                    System.out.println("列頭:"+String.join(csvDelimiter, fieldNames));
                    dataList.add(fieldNames);
                    parquetInfo.put("head",dataList);
                    dataList=new ArrayList<>();
                }
                int i = 0;
                String[]dataString=new String[fieldNames.length];
                //讀取資料獲取列頭資訊
                for (final String fieldName : fieldNames) {
                    String recordData=record.get(fieldName).toString();
                    if(recordData.contains("type")){
                        List<HashMap> dataFormValue=JSONArray.parseArray(JSONObject.parseObject(recordData).get("values").toString(),HashMap.class);
                        StringBuilder datas = new StringBuilder();
                        for(HashMap data:dataFormValue){
                            datas.append(data.get("element").toString()).append(",");
                        }
                        datas.deleteCharAt(datas.length() - 1);
                        recordData=datas.toString();
                    }
                    dataString[i++] =recordData;
                }
                dataList.add(dataString);
                ++x;
            }
        }
        parquetInfo.put("data",dataList);
        return parquetInfo;
    }

    private static String[] getFieldNames(final Schema.Field[] fields) {
        final String[] fieldNames = new String[fields.length];
        int i = 0;
        for (final Schema.Field field : fields) {
            fieldNames[i++] = field.name();
        }
        return fieldNames;
    }
}