基礎備忘（生成EXCEL和CSV文件）

生成EXCEL和CSV文件

通過POI操作生成EXCEL本身沒有什麼難度，主要記住以下幾個概念就行。

引包，excel本身有不同版本，POI包也有所不同。
workbook、sheet、row、cell、style之間的關係

添加maven引用

  <dependency>
            <groupId>com.opencsv</groupId>
            <artifactId>opencsv</artifactId>
            <version>5.7.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>5.0.0</version>
        </dependency>

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>5.0.0</version>
   </dependency>

workbook、sheet、row、cell、style之間的關係

XSSFWorkbook: 可以看作整個excel文件
XSSFSheet：excel中的一個sheet（一個XSSFWorkbook可以有多個sheet）
XSSFRow： sheet中的行（同理一個sheet中有很多行）
XSSFCell：單元格（一行中有很多個單元格）
XSSFCellStyle：單元格樣式，像背景顏色、邊框、字體等都是通過創建XSSFCellStyle對象然後賦值給到某個具體的XSSFCell實現的
sheet.addMergedRegion：合併多列

package com.kms.console.utils;

import java.io.*;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.util.Date;
import java.util.List;

import com.opencsv.CSVWriter;
import org.apache.poi.ss.usermodel.*;

import com.kms.console.enums.ReportFilePrefixEnum;
import com.kms.console.enums.ReportFileTileEnum;
import com.kms.console.enums.ReportFileTypeEnum;
import com.opencsv.bean.StatefulBeanToCsv;
import com.opencsv.bean.StatefulBeanToCsvBuilder;
import com.opencsv.exceptions.CsvDataTypeMismatchException;
import com.opencsv.exceptions.CsvRequiredFieldEmptyException;

import lombok.extern.slf4j.Slf4j;
import org.apache.poi.xssf.usermodel.*;


@Slf4j
public class ReportUtil<T> {

    /**
     * 根據報表查詢數據生成excel文件
     *
     * @param reportDataList      查詢到的數據集合
     * @param reportFileTileEnum  報表類別枚舉
     * @param clazz               查詢到的數據實體類型，便於反射生成excel表格字段
     * @param generatorDateString 報表生成日期字符串
     * @param beginTime           開始時間
     * @param endTime             結束時間
     */
    public String createExcel(List<T> reportDataList, ReportFileTileEnum reportFileTileEnum, ReportFilePrefixEnum reportFilePrefixEnum, Class clazz, String filePath, String generatorDateString, Date beginTime, Date endTime) {
        String fullFilePath = getFullFilePath(reportFilePrefixEnum, filePath, generatorDateString, ReportFileTypeEnum.XLSX);
        File file = new File(fullFilePath);
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
        }
        //創建工作薄
        try (XSSFWorkbook  wb = new XSSFWorkbook()) {
            //新建一個sheet
            XSSFSheet sheet = wb.createSheet("sheet1");
            Field[] declaredFields = clazz.getDeclaredFields();
//            標題、彙總信息等
            createBannerSegment(reportDataList, reportFileTileEnum, generatorDateString, beginTime, endTime, wb, sheet);
//            生成表格數據部分
            createDataTableSegment(reportDataList, wb, sheet, declaredFields);
            FileOutputStream out = null;
            // 寫文件
            try {
                out = new FileOutputStream(fullFilePath);
                out.flush();
                wb.write(out);
            } catch (FileNotFoundException ex) {
                log.error("report file generator failed,The file does not exist or the path is wrong", ex);
            } catch (IOException e) {
                log.error("report file generator failed,An exception occurred while writing the file ", e);
            } finally {
                try {
                    if (out != null) {
                        out.close();
                    }
                } catch (IOException e) {
                    log.error("close FileOutputStream failed", e);
                }
            }
        } catch (Exception ex) {
            log.error("generator excel workbook failed", ex);
        }
        return fullFilePath;
    }

    /**
     * 標題、彙總信息等
     *
     * @param reportDataList
     * @param reportFileTileEnum
     * @param generatorDateString
     * @param beginTime
     * @param endTime
     * @param wb
     * @param sheet
     */
    private void createBannerSegment(List<T> reportDataList, ReportFileTileEnum reportFileTileEnum, String generatorDateString, Date beginTime, Date endTime, XSSFWorkbook  wb, XSSFSheet  sheet) {
//        XSSFRow rowFirst = sheet.createRow(0);
//        XSSFCell cellFirst = rowFirst.createCell(0);
//        cellFirst.setCellValue(titleString);
//        XSSFCellStyle rowFirstStyle = wb.createCellStyle();
//        rowFirstStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
//        XSSFColor rowFirstColor = new XSSFColor(new java.awt.Color(0xDDEBF7), new DefaultIndexedColorMap());
//        rowFirstStyle.setFillForegroundColor(rowFirstColor);
//        rowFirstStyle.setAlignment(HorizontalAlignment.CENTER);
//        cellFirst.setCellStyle(rowFirstStyle);
//        sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, declaredFields.length));
//        報表內容
//        XSSFRow rowContent = sheet.createRow(2);
//        XSSFCell contentCell = rowContent.createCell(0);
//        contentCell.setCellValue("report content");
//        XSSFCellStyle contentStyle = wb.createCellStyle();
//        contentStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
//        XSSFColor contColor = new XSSFColor(new java.awt.Color(0xFFC000), new DefaultIndexedColorMap());
//        contentStyle.setFillForegroundColor(contColor);
//        contentCell.setCellStyle(contentStyle);
        //        報表內容下面表格樣式
        XSSFCellStyle contentTableStyle = wb.createCellStyle();
        contentTableStyle.setBorderBottom(BorderStyle.THIN);
        contentTableStyle.setBorderTop(BorderStyle.THIN);
        contentTableStyle.setBorderRight(BorderStyle.THIN);
        contentTableStyle.setBorderLeft(BorderStyle.THIN);
//        報表週期
        XSSFRow cycleRow = sheet.createRow(3);
        XSSFCell periodCell0 = cycleRow.createCell(0);
        periodCell0.setCellValue("periodNo");
        periodCell0.setCellStyle(contentTableStyle);
        XSSFCell periodCell1 = cycleRow.createCell(1);
        periodCell1.setCellValue(reportFileTileEnum.getValue() + "00001" + generatorDateString);
        periodCell1.setCellStyle(contentTableStyle);
//        開始時間
        XSSFRow beginTimeRow = sheet.createRow(4);
        XSSFCell beginTimeCell0 = beginTimeRow.createCell(0);
        beginTimeCell0.setCellValue("startTime");
        beginTimeCell0.setCellStyle(contentTableStyle);
        XSSFCell beginTimeCell1 = beginTimeRow.createCell(1);
        beginTimeCell1.setCellValue(DateUtils.formatDate(beginTime));
        beginTimeCell1.setCellStyle(contentTableStyle);
//        結束時間
        XSSFRow endTimeRow = sheet.createRow(5);
        XSSFCell endTimeCell0 = endTimeRow.createCell(0);
        endTimeCell0.setCellValue("endTime");
        endTimeCell0.setCellStyle(contentTableStyle);
        XSSFCell endTimeCell1 = endTimeRow.createCell(1);
        endTimeCell1.setCellValue(DateUtils.formatDate(endTime));
        endTimeCell1.setCellStyle(contentTableStyle);
//        總條數
        XSSFRow totalCountRow = sheet.createRow(6);
        XSSFCell totalCountCell0 = totalCountRow.createCell(0);
        totalCountCell0.setCellValue("totalCount");
        totalCountCell0.setCellStyle(contentTableStyle);
        XSSFCell totalCountCell1 = totalCountRow.createCell(1);
        totalCountCell1.setCellValue(reportDataList.size());
        totalCountCell1.setCellStyle(contentTableStyle);
//         dataSetTitle
//        XSSFRow dataSetTitle = sheet.createRow(9);
//        XSSFCell dataSetTitleCell = dataSetTitle.createCell(0);
//        dataSetTitleCell.setCellValue(dataSetTitleString);
//        CellStyle dataSetTitleStyle = wb.createCellStyle();
//        Font dataSetTitleFont = wb.createFont();
//        dataSetTitleFont.setFontHeightInPoints((short) 11);
//        dataSetTitleStyle.setFont(dataSetTitleFont);
//        dataSetTitleCell.setCellStyle(dataSetTitleStyle);
//        sheet.addMergedRegion(new CellRangeAddress(9, 9, 0, declaredFields.length));
    }

    /**
     * 表格數據部分
     *
     * @param reportDataList
     * @param wb
     * @param sheet
     * @param declaredFields
     */
    private void createDataTableSegment(List<T> reportDataList, XSSFWorkbook  wb, XSSFSheet  sheet, Field[] declaredFields) {
        String[] headers = new String[declaredFields.length];
        for (int i = 0; i < declaredFields.length; i++) {
            headers[i] = declaredFields[i].getName();
        }
//        表格詳細數據列名稱
        XSSFRow dataSetHeader = sheet.createRow(10);
        //寫詳細數據標題行的每一個單元格
        for (int i = 0; i < headers.length; i++) {
            //獲取第一行的每個單元格
            XSSFCell cell = dataSetHeader.createCell(i);
            //往單元格里寫數據
            cell.setCellValue(headers[i]);
            XSSFCellStyle style = wb.createCellStyle();
            XSSFColor xssfColor = new XSSFColor(new java.awt.Color(0xFFF2CC), new DefaultIndexedColorMap());
            style.setFillForegroundColor(xssfColor);
            style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
            style.setBorderTop(BorderStyle.THIN);
            style.setBorderBottom(BorderStyle.THIN);
            style.setBorderLeft(BorderStyle.THIN);
            style.setBorderRight(BorderStyle.THIN);
            cell.setCellStyle(style);
            //設置每列的列寬
//            sheet.trackAllColumnsForAutoSizing();
            sheet.autoSizeColumn(i,true);
        }
        //寫數據集
        for (int i = 0; i < reportDataList.size(); i++) {
            //創建數據行
            XSSFRow row = sheet.createRow(i + dataSetHeader.getRowNum() + 1);
            for (int j = 0; j < headers.length; j++) {
                Field f = declaredFields[j];
                f.setAccessible(true);
                try {
                    if (f.get(reportDataList.get(i)) != null) {
                        XSSFCell dataCell = row.createCell(j);
                        CellStyle dataCommonCellStyle = wb.createCellStyle();
                        dataCommonCellStyle.setBorderTop(BorderStyle.THIN);
                        dataCommonCellStyle.setBorderBottom(BorderStyle.THIN);
                        dataCommonCellStyle.setBorderLeft(BorderStyle.THIN);
                        dataCommonCellStyle.setBorderRight(BorderStyle.THIN);
                        Object cellValue = f.get(reportDataList.get(i));
                        //設置對應單元格的值
                        //時間類型
                        if (f.getType() == Date.class) {
                            dataCell.setCellValue((Date) cellValue);
                            CreationHelper createHelper = wb.getCreationHelper();
                            dataCommonCellStyle.setDataFormat(createHelper.createDataFormat().getFormat("yyyy/M/d H:mm:ss"));
//                         貨幣類型
                        } else if (f.getType() == BigDecimal.class) {
                            dataCell.setCellValue(Double.parseDouble(cellValue.toString()));
                        } else if (f.getType() == Long.class) {
                            dataCell.setCellValue((Long) cellValue);
                        } else {
                            dataCell.setCellValue(cellValue.toString());
                        }
                        dataCell.setCellStyle(dataCommonCellStyle);
                    } else {
                        row.createCell(j).setCellValue("");
                    }
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                }

            }
        }
    }

    /**
     * 拼文件全路徑
     *
     * @param reportFilePrefixEnum
     * @param filePath
     * @param generatorDateString
     * @return
     */
    private String getFullFilePath(ReportFilePrefixEnum reportFilePrefixEnum, String filePath, String generatorDateString, ReportFileTypeEnum reportFileTypeEnum) {
        String fileName = reportFilePrefixEnum.getValue() + "_" + generatorDateString + "." + reportFileTypeEnum.getValue();
        String fullFilePath = filePath + File.separator + fileName;
        return fullFilePath;
    }

    public String createCsv(List<T> reportDataList, ReportFileTileEnum reportFileTileEnum, ReportFilePrefixEnum reportFilePrefixEnum, Class clazz, String filePath, String generatorDateString, Date beginTime, Date endTime) {
        String fullFilePath = getFullFilePath(reportFilePrefixEnum, filePath, generatorDateString, ReportFileTypeEnum.CSV);
        File file = new File(fullFilePath);
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
        }
        Writer writer = null;
        try {
            writer = new FileWriter(fullFilePath);
            CSVWriter csvWriter=new CSVWriter(writer);
//            寫報表內容部分，如報表名稱，報表時間段，報表總數等
            String periodRowString = "periodNo," + reportFileTileEnum.getValue() + "00001" + generatorDateString;
            String[] periodRow =  periodRowString.split(",");
            csvWriter.writeNext(periodRow);
            String startTimeRowString = "startTime," + DateUtils.formatDate(beginTime);
            String[] startTimeRow = startTimeRowString.split(",");
            csvWriter.writeNext(startTimeRow);
            String endTimeRowString = "endTime," + DateUtils.formatDate(endTime);
            String[] endTimeRow = endTimeRowString.split(",");
            csvWriter.writeNext(endTimeRow);
            String totalCountString="totalCount,"+reportDataList.size();
            String[] totalCountRow = totalCountString.split(",");
            csvWriter.writeNext(totalCountRow);
            //空行隔開
            csvWriter.writeNext(new String[]{});
            //寫datatable暑假
            StatefulBeanToCsv beanToCsv = new StatefulBeanToCsvBuilder(writer).build();
            beanToCsv.write(reportDataList);


        } catch (Exception e) {
            log.error("create csv file failed", e);
        } finally {
            try {
                if (writer != null) {
                    writer.close();
                }
            } catch (Exception ex) {
                log.error("close writer failed", ex);
            }
        }
        return fullFilePath;
    }


  
}

總是有些基礎內容用過就忘掉了，缺少總結記錄。在此記錄下來便於以後查找也爲遇到類似問題的人一個小小的幫助。

基礎備忘（生成EXCEL和CSV文件）

生成EXCEL和CSV文件

添加maven引用

workbook、sheet、row、cell、style之間的關係

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基礎備忘（文件下載）

基礎備忘（生成EXCEL和CSV文件）

基礎備忘(發送htm正文帶圖片並且帶附件的郵件)

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

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