json 格式转 csv 格式文件

引入 csv 文件依赖

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-csv</artifactId>
            <version>1.8</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.8.0</version>
        </dependency>

json 文件转换成 csv 文件

对于 csv 文件，第一行是表头。本示例假设 json 文件中第一行代表一个 json 对象，生成 csv 文件表头只有一列，即："test"

    /**
     * 固定csv头名
     */
    public static String[] tableHeaderArr = {"test"};


    private static void testValidSkuGenerateV3() {
        //1. 读入 json 格式的文件
        String file = FileUtil.read("/Users/xxx/test/quake_file/input/yyy.txt", null);
        String[] jsonObjs = file.split(System.getProperty("line.separator"));
        List<Object[]> requestList = new ArrayList<>(jsonObjs.length);
        for (String jsonObjStr : jsonObjs) {
            try {
                //将每一个 json 解析成 对象
                SgCouponValidSkuRequest request = JSON.parseObject(jsonObjStr, SgCouponValidSkuRequest.class);
                System.out.println(JSON.toJSONString(request));
                String result = JacksonUtils.serialize(request);
                requestList.add(new Object[]{result});
            } catch (Exception e) {
                System.out.println(e);
            }
        }

        byte[] bytes = ExportCsvUtil.writeCsvAfterToBytes(ExportCsvUtil.tableHeaderArr, requestList);
        try {
            ExportCsvUtil.saveFile("/Users/xxx/test/quake_file/output/yyy.csv", bytes);
        } catch (Exception e) {
            System.out.println(e);
        }
    }

保存 csv 文件格式的工具类

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.io.ByteOrderMark;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.List;


public class ExportCsvUtil {

    private static final Logger logger = LoggerFactory.getLogger(ExportCsvUtil.class);

    /**
     * 固定csv文件的表头名称
     */
    public static String[] tableHeaderArr = {"test"};

    /**
     * 写CSV并转换为字节流
     * @param tableHeaderArr 表头
     * @param cellList 数据
     * @return
     */
    public static byte[] writeDataAfterToBytes(String[] tableHeaderArr, List<String> cellList) {
        byte[] bytes = new byte[0];
        ByteArrayOutputStream byteArrayOutputStream = null;
        OutputStreamWriter outputStreamWriter = null;
        BufferedWriter bufferedWriter = null;
        try {
            byteArrayOutputStream = new ByteArrayOutputStream();
            outputStreamWriter = new OutputStreamWriter(byteArrayOutputStream, StandardCharsets.UTF_8);
            bufferedWriter = new BufferedWriter(outputStreamWriter);
            //excel文件需要通过文件头的bom来识别编码，而CSV文件格式不自带bom,所以写文件时，需要先写入bom头，否则excel打开乱码
            bufferedWriter.write(new String(ByteOrderMark.UTF_8.getBytes()));
            //写表头
            StringBuilder sb = new StringBuilder();
            String tableHeader = String.join(",", tableHeaderArr);
            sb.append(tableHeader + StringUtils.CR + StringUtils.LF);
            for (String rowCell : cellList) {
                sb.append(rowCell + StringUtils.CR + StringUtils.LF);
            }
            bufferedWriter.write(sb.toString());
            bufferedWriter.flush();
            //把输出流转换字节流
            bytes = byteArrayOutputStream.toString(StandardCharsets.UTF_8.name()).getBytes();
            return bytes;
        } catch (IOException e) {
            logger.error("writeDataAfterToBytes IOException:{}", e.getMessage(), e);
        } finally {
            try {
                if (bufferedWriter != null) {
                    bufferedWriter.close();
                }
                if (outputStreamWriter != null) {
                    outputStreamWriter.close();
                }
                if (byteArrayOutputStream != null) {
                    byteArrayOutputStream.close();
                }
            } catch (IOException e) {
                logger.error("iostream close IOException:{}", e.getMessage(), e);
            }
        }
        return bytes;
    }

    /**
     * 写CSV并转换为字节流
     * @param headers 表头
     * @param cellList 表数据
     * @return
     */
    public static byte[] writeCsvAfterToBytes(String[] headers,List<Object[]> cellList) {
        byte[] bytes = new byte[0];
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(byteArrayOutputStream, StandardCharsets.UTF_8);
        BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
        CSVPrinter csvPrinter = null;
        try {
            //创建csvPrinter并设置表格头
            csvPrinter = new CSVPrinter(bufferedWriter, CSVFormat.DEFAULT.withHeader(headers));
            //写数据
            csvPrinter.printRecords(cellList);
            csvPrinter.flush();
            bytes = byteArrayOutputStream.toString(StandardCharsets.UTF_8.name()).getBytes();
        } catch (IOException e) {
            logger.error("writeCsv IOException:{}", e.getMessage(), e);
        } finally {
            try {
                if (csvPrinter != null) {
                    csvPrinter.close();
                }
                if (bufferedWriter != null) {
                    bufferedWriter.close();
                }
                if (outputStreamWriter != null) {
                    outputStreamWriter.close();
                }
                if (byteArrayOutputStream != null) {
                    byteArrayOutputStream.close();
                }
            } catch (IOException e) {
                logger.error("iostream close IOException:{}", e.getMessage(), e);
            }
        }
        return bytes;
    }

    public static void saveFile(String filename, byte[] data) throws Exception {
        if (data != null) {
            File file = new File(filename);
            if (file.exists()) {
                file.delete();
            }
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(data, 0, data.length);
            fos.flush();
            fos.close();
        }
    }
}