Excel常用导入导出工具类

import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
import com.ylsw.entity.ExcelColumn;
import org.apache.commons.lang3.BooleanUtils;
import org.apache.commons.lang3.CharUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.MediaType;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.net.URLEncoder;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Collectors;
import java.util.stream.Stream;


/**
 * Excel常用导入导出工具类
 * 注意（踩过的坑）：如果前端定义了文件名，后端再定义是没作用的，一次开始导出的是.xlsx 后缀的文件，后面要求.xls 的，
 * 这个时候后端创建表格就要用HSSFWorkbook() 创建，而且前端一定要改文件名的后缀，（只是后端处理文件名的）不然导出的文件会有问题。
 **/
public class ExcelUtils {

    private final static Logger log = LoggerFactory.getLogger(ExcelUtils.class);

    private final static String EXCEL2003 = "xls";
    private final static String EXCEL2007 = "xlsx";

    public static <T> List<T> readExcel(String path, Class<T> cls, MultipartFile file) throws IOException, IllegalAccessException, InstantiationException {

        //获取文件名称
        String fileName = file.getOriginalFilename();
        if (!fileName.matches("^.+\\.(?i)(xls)$") && !fileName.matches("^.+\\.(?i)(xlsx)$")) {
            log.error("上传文件格式不正确");
        }

        List<T> dataList = new ArrayList<>();
        Workbook workbook = null;


        InputStream is = file.getInputStream();

        if (fileName.endsWith(EXCEL2007)){
            workbook = new XSSFWorkbook(is);
        }

        if (fileName.endsWith(EXCEL2003)){
            workbook = new HSSFWorkbook(is);
        }

        if (workbook != null){
            //类映射  注解 value-->bean columns
            Map<String, List<Field>> classMap = new HashMap<>();
            List<Field> fields = Stream.of(cls.getDeclaredFields()).collect(Collectors.toList());
            fields.forEach(field -> {
                ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                if (annotation !=null){
                    String value = annotation.value();
                    if (StringUtils.isBlank(value)){
                        return;
                    }
                    if(!classMap.containsKey(value)){
                        classMap.put(value,new ArrayList<>());
                    }

                    field.setAccessible(true);
                    classMap.get(value).add(field);
                }
            });

            //索引-->columns
            Map<Integer, List<Field>> reflectionMap = new HashMap<>(16);
            //默认读取第一个sheet
            Sheet sheet = workbook.getSheetAt(0);

            boolean firstRow = true;
            for(int i = sheet.getFirstRowNum(); i <= sheet.getLastRowNum();i++){
                Row row = sheet.getRow(i);

                //首行  提取注解
                if (firstRow){
                    for (int j = row.getFirstCellNum(); j<= row.getLastCellNum();j++){
                        Cell cell = row.getCell(j);
                        String cellValue = getCellValue(cell);
                        if (classMap.containsKey(cellValue)){
                            reflectionMap.put(j,classMap.get(cellValue));
                        }
                    }
                    firstRow = false;
                }else{
                    //忽略空白行
                    if(row == null){
                        continue;
                    }

                    T t = cls.newInstance();

                    //判断是否为空白行
                    boolean allBlank = true;
                    for (int j = row.getFirstCellNum(); j<= row.getLastCellNum(); j++){
                        if(reflectionMap.containsKey(j)){
                            Cell cell = row.getCell(j);
                            String cellValue = getCellValue(cell);
                            if (StringUtils.isNotBlank(cellValue)){
                                allBlank = false;
                            }
                            List<Field> fieldList = reflectionMap.get(j);
                            fieldList.forEach(x ->{
                                try {
                                    handleField(t, cellValue, x);
                                } catch (Exception e) {
                                    e.printStackTrace();
                                        log.error(String.format("reflect field:%s value:%s exception!", x.getName(), cellValue), e);
                                }
                            });
                        }
                    }
                    if (!allBlank) {
                        dataList.add(t);
                    } else {
                        log.warn(String.format("row:%s is blank ignore!", i));
                    }

                }
            }

        }

            try {
                workbook.close();
            } catch (Exception e) {
                log.error(String.format("parse excel exception!"), e);
            }

        return dataList;
    }

    private static <T> void handleField(T t, String value, Field field) throws Exception {
        Class<?> type = field.getType();
        if (type == null || type == void.class || StringUtils.isBlank(value)) {
            return;
        }
        if (type == Object.class) {
            field.set(t, value);
            //数字类型
        } else if (type.getSuperclass() == null || type.getSuperclass() == Number.class) {
            if (type == int.class || type == Integer.class) {
                field.set(t, NumberUtils.toInt(value));
            } else if (type == long.class || type == Long.class) {
                field.set(t, NumberUtils.toLong(value));
            } else if (type == byte.class || type == Byte.class) {
                field.set(t, NumberUtils.toByte(value));
            } else if (type == short.class || type == Short.class) {
                field.set(t, NumberUtils.toShort(value));
            } else if (type == double.class || type == Double.class) {
                field.set(t, NumberUtils.toDouble(value));
            } else if (type == float.class || type == Float.class) {
                field.set(t, NumberUtils.toFloat(value));
            } else if (type == char.class || type == Character.class) {
                field.set(t, CharUtils.toChar(value));
            } else if (type == boolean.class) {
                field.set(t, BooleanUtils.toBoolean(value));
            } else if (type == BigDecimal.class) {
                field.set(t, new BigDecimal(value));
            }
        } else if (type == Boolean.class) {
            field.set(t, BooleanUtils.toBoolean(value));
        } else if (type == Date.class) {
            //
            field.set(t, value);
        } else if (type == String.class) {
            field.set(t, value);
        } else {
            Constructor<?> constructor = type.getConstructor(String.class);
            field.set(t, constructor.newInstance(value));
        }
    }

    private static String getCellValue(Cell cell) {
        if (cell == null) {
            return "";
        }
        if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
            if (HSSFDateUtil.isCellDateFormatted(cell)) {
                return HSSFDateUtil.getJavaDate(cell.getNumericCellValue()).toString();
            } else {
                return new BigDecimal(cell.getNumericCellValue()).toString();
            }
        } else if (cell.getCellType() == Cell.CELL_TYPE_STRING) {
            return StringUtils.trimToEmpty(cell.getStringCellValue());
        } else if (cell.getCellType() == Cell.CELL_TYPE_FORMULA) {
            return StringUtils.trimToEmpty(cell.getCellFormula());
        } else if (cell.getCellType() == Cell.CELL_TYPE_BLANK) {
            return "";
        } else if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) {
            return String.valueOf(cell.getBooleanCellValue());
        } else if (cell.getCellType() == Cell.CELL_TYPE_ERROR) {
            return "ERROR";
        } else {
            return cell.toString().trim();
        }

    }


    public static <T> void writeExcel(HttpServletResponse response, List<T> dataList, Class<T> cls, String fileName){
        Field[] fields = cls.getDeclaredFields();
        List<Field> fieldList = Arrays.stream(fields)
                .filter(field -> {
                    ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                    if (annotation != null && annotation.col() > 0) {
                        field.setAccessible(true);
                        return true;
                    }
                    return false;
                }).sorted(Comparator.comparing(field -> {
                    int col = 0;
                    ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                    if (annotation != null) {
                        col = annotation.col();
                    }
                    return col;
                })).collect(Collectors.toList());

        Workbook wb = new XSSFWorkbook();
        Sheet sheet = wb.createSheet("Sheet1");
        AtomicInteger ai = new AtomicInteger();
        {
            Row row = sheet.createRow(ai.getAndIncrement());
            AtomicInteger aj = new AtomicInteger();
            //写入头部
            fieldList.forEach(field -> {
                ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                String columnName = "";
                if (annotation != null) {
                    columnName = annotation.value();
                }
                Cell cell = row.createCell(aj.getAndIncrement());

                CellStyle cellStyle = wb.createCellStyle();
//                标题栏合并
//                cellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());
//                cellStyle.setFillPattern(CellStyle.SOLID_FOREGROUND);
                //设置标题行背景颜色：黄色YELLOW;   蓝色TURQUOISE    设置颜色教程 https://www.cnblogs.com/vofill/p/11230387.html
                cellStyle.setFillForegroundColor(IndexedColors.YELLOW.getIndex());//
                cellStyle.setFillPattern(CellStyle.SOLID_FOREGROUND);

                cellStyle.setAlignment(CellStyle.ALIGN_CENTER);//居中

                Font font = wb.createFont();
                font.setBold(true);//字体加粗
                font.setBoldweight(Font.BOLDWEIGHT_NORMAL);
                cellStyle.setFont(font);
                cell.setCellStyle(cellStyle);
                cell.setCellValue(columnName);
            });
        }
        if (CollectionUtils.isNotEmpty(dataList)) {
            dataList.forEach(t -> {
                Row row1 = sheet.createRow(ai.getAndIncrement());
                AtomicInteger aj = new AtomicInteger();
                fieldList.forEach(field -> {
                    Class<?> type = field.getType();
                    Object value = "";
                    try {
                        value = field.get(t);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    Cell cell = row1.createCell(aj.getAndIncrement());
                    if (value != null) {
                        if (type == Date.class) {
                            cell.setCellValue(value.toString());
                        } else {
                            cell.setCellValue(value.toString());
                        }
                        cell.setCellValue(value.toString());
                    }
                });
            });
        }
        //冻结窗格
        wb.getSheet("Sheet1").createFreezePane(0, 1, 0, 1);
        //浏览器下载excel
        buildExcelDocument(fileName+".xlsx",wb,response);
        //生成excel文件
//        buildExcelFile(".\\default.xlsx",wb);
    }

    /**
     * 浏览器下载excel
     * @param fileName
     * @param wb
     * @param response
     */

    private static  void  buildExcelDocument(String fileName, Workbook wb, HttpServletResponse response){
        try {
            response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
            response.setHeader("Content-Disposition", "attachment;filename="+ URLEncoder.encode(fileName, "utf-8"));
            response.flushBuffer();
            wb.write(response.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 生成excel文件
     * @param path 生成excel路径
     * @param wb
     */
    private static  void  buildExcelFile(String path, Workbook wb){

        File file = new File(path);
        if (file.exists()) {
            file.delete();
        }
        try {
            wb.write(new FileOutputStream(file));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

// 导出后缀为.xls
    public static <T> void writeExcelType(HttpServletResponse response, List<T> dataList, Class<T> cls, String fileName) {
        Field[] fields = cls.getDeclaredFields();
        List<Field> fieldList = (List)Arrays.stream(fields).filter((field) -> {
            ExcelColumn annotation = (ExcelColumn)field.getAnnotation(ExcelColumn.class);
            if (annotation != null && annotation.col() > 0) {
                field.setAccessible(true);
                return true;
            } else {
                return false;
            }
        }).sorted(Comparator.comparing((field) -> {
            int col = 0;
            ExcelColumn annotation = (ExcelColumn)field.getAnnotation(ExcelColumn.class);
            if (annotation != null) {
                col = annotation.col();
            }

            return col;
        })).collect(Collectors.toList());
        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet("Sheet1");
        AtomicInteger ai = new AtomicInteger();
        HSSFRow row = sheet.createRow(ai.getAndIncrement());
        AtomicInteger aj = new AtomicInteger();
        fieldList.forEach((field) -> {
            ExcelColumn annotation = (ExcelColumn)field.getAnnotation(ExcelColumn.class);
            String columnName = "";
            if (annotation != null) {
                columnName = annotation.value();
            }

            HSSFCell cell = row.createCell(aj.getAndIncrement());
            CellStyle cellStyle = wb.createCellStyle();
            cellStyle.setFillForegroundColor(IndexedColors.YELLOW.getIndex());
            cellStyle.setFillPattern((short)1);
            cellStyle.setAlignment((short)2);
            Font font = wb.createFont();
            font.setBold(true);
            font.setBoldweight((short)400);
            cellStyle.setFont(font);
            cell.setCellStyle(cellStyle);
            cell.setCellValue(columnName);
        });
        if (CollectionUtils.isNotEmpty(dataList)) {
            dataList.forEach((t) -> {
                Row row1 = sheet.createRow(ai.getAndIncrement());
                AtomicInteger aj = new AtomicInteger();
                fieldList.forEach((field) -> {
                    Class<?> type = field.getType();
                    Object value = "";

                    try {
                        value = field.get(t);
                    } catch (Exception var7) {
                        var7.printStackTrace();
                    }

                    Cell cell = row1.createCell(aj.getAndIncrement());
                    if (value != null) {
                        if (type == Date.class) {
                            cell.setCellValue(value.toString());
                        } else {
                            cell.setCellValue(value.toString());
                        }

                        cell.setCellValue(value.toString());
                    }

                });
            });
        }

        wb.getSheet("Sheet1").createFreezePane(0, 1, 0, 1);
        buildExcelDocument(fileName, wb, response);
    }

}