JAVA生成ORC格式文件

一、背景

由于需要用到用java生成hdfs文件并上传到指定目录中，在Hive中即可查询到数据，基于此背景，开发此工具类

ORC官方网站：https://orc.apache.org/

二、支持数据类型

三、工具开发

package com.xx.util;

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONArray;
import com.alibaba.fastjson2.JSONObject;
import lombok.extern.slf4j.Slf4j;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.exec.vector.BytesColumnVector;
import org.apache.hadoop.hive.ql.exec.vector.VectorizedRowBatch;
import org.apache.orc.OrcFile;
import org.apache.orc.TypeDescription;
import org.apache.orc.Writer;

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

@Slf4j
public class ORCUtil {

    /**
     * 将JSON数据转换成ORC文件并上传到HDFS中
     *
     * @param source json串，必须是和数据表顺序一致的json串
     * @param dbFields 存在数据库中的Hive表元数据字段
     * @param target 目标文件路径，包含文件名和.orc后缀
     * @throws IOException
     */
    public static void write(String source, List<String> dbFields, String target) throws IOException {
        long start = System.currentTimeMillis();
        Configuration conf = new Configuration();
        TypeDescription schema = TypeDescription.createStruct();
        JSONArray datas = JSONArray.parseArray(source);
        ArrayList<String> keys = new ArrayList<>(datas.getJSONObject(0).keySet());
        for (String flied : dbFields) {
            schema.addField(flied, TypeDescription.createString());
        }
        Writer writer = OrcFile.createWriter(new Path(target),
                OrcFile.writerOptions(conf)
                        .setSchema(schema).stripeSize(67108864)
                        .bufferSize(64 * 1024)
                        .blockSize(128 * 1024 * 1024)
                        .rowIndexStride(10000)
                        .blockPadding(true));
        VectorizedRowBatch batch = schema.createRowBatch();
        ArrayList<BytesColumnVector> bytesColumnVectors = new ArrayList<>();
        for (int i = 0; i < batch.numCols; i++) {
            bytesColumnVectors.add((BytesColumnVector) batch.cols[i]);
        }
        for (Object data : datas) { 
            JSONObject dataObj = (JSONObject) data;
            int row = batch.size++; 
            for (int i = 0; i < dbFields.size(); i++) {
//                数据对象上的字段
                if(keys.contains(dbFields.get(i))){
                    bytesColumnVectors.get(i).setVal(row, dataObj.getString(dbFields.get(i)).getBytes());
                }else{
                    bytesColumnVectors.get(i).setVal(row, "".getBytes());
                }
            }
        }

        long stop = System.currentTimeMillis();
        log.info("将json转换为orc文件花费的时间是 " + (stop - start) / 1000 + "秒");
        if (batch.size != 0) {
            writer.addRowBatch(batch);
            batch.reset();
        }
        writer.close();
    }
}

四、总结

基于此可以根据实际业务场景可以生成数据并上传到HDFS上提供Hive查询