json生成excel文件

package excel;

import com.alibaba.fastjson.JSONObject;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.UUID;

public class excel {

    public static void main(String[] args) throws IOException {
        jsonToExcel("C://Users//xxx//Desktop//aa.json", "D://");

    }

    static void jsonToExcel(String readPath, String outputPath) throws IOException {
        Set keys = null;
        FileReader fileReader = new FileReader(readPath);
        BufferedReader br = new BufferedReader(fileReader);
        String str;
        int roll = 0;
        int cellNo = 0;
        int count = 0;
        int page = 50000;
        int size = (int) br.lines().count();
        fileReader = new FileReader(readPath);
        br = new BufferedReader(fileReader);
        List jsonObjectList = new ArrayList<>();
        while ((str = br.readLine()) != null) {
            count ++;
            JSonObject jsonObject = JSONObject.parseObject(str);
            jsonObjectList.add(jsonObject);
            //每5万条输出一次
            if ((count % page == 0 && count != 0 ) || count >= size) {
                HSSFWorkbook wb = new HSSFWorkbook();

                HSSFSheet sheet = wb.createSheet("sheet0");
                HSSFRow row ;
                //表头拼接
                if (keys == null) {
                    keys = jsonObject.keySet();
                    row = sheet.createRow(roll);
                    for (String s : keys) {
                        HSSFCell cell = row.createCell(cellNo ++);
                        cell.setCellValue(s);
                    }
                    cellNo = 0;
                    roll ++;

                }

                //行数据生成
                for (JSonObject object : jsonObjectList) {
                    row = sheet.createRow(roll);
                    for (String s : keys) {
                        HSSFCell cell = row.createCell(cellNo ++ );
                        cell.setCellValue(object.getString(s));
                    }
                    cellNo = 0;
                    roll ++;

                }

                //文件输出
                FileOutputStream output = new FileOutputStream(outputPath + "target" + UUID.randomUUID() + ".xls");
                wb.write(output);
                wb.close();
                output.flush();
                output.close();
                roll = 0;
                keys = null;
                jsonObjectList.clear();
            }
        }
        br.close();
        fileReader.close();
        System.out.println("生成完毕");
    }
}