• Java之POI导出Excel(一)：单sheet

    相信在大部分的web项目中都会有导出导入Excel的需求，今天我们就来看看如何用Java代码去实现 用POI导出Excel表格。

    一、pom引用

    pom文件中，添加以下依赖

    查看代码 
     
        <dependency>
            <groupId>org.apache.poigroupId>
            <artifactId>poiartifactId>
            <version>5.2.2version>
            <scope>compilescope>
        dependency>
        <dependency>
            <groupId>org.apache.poigroupId>
            <artifactId>poi-ooxmlartifactId>
            <version>5.2.2version>
            <scope>compilescope>
        dependency>

    二、工具类util

    1.ExcelClassField

    查看代码 
     package com.***;
 
import lombok.Data;
 
import java.util.LinkedHashMap;
 
/**
 * @description: excel字段
 * @author: ***
 * @date: 2022/6/21
 */
@Data
public class ExcelClassField {
    /**
     * 字段名称
     */
    private String fieldName;
 
    /**
     * 表头名称
     */
    private String name;
 
    /**
     * 映射关系
     */
    private LinkedHashMap kvMap;
 
    /**
     * 示例值
     */
    private Object example;
 
    /**
     * 排序
     */
    private int sort;
 
    /**
     * 是否为注解字段：0-否，1-是
     */
    private int hasAnnotation;
 
}

     2.ExcelExport（导出Excel用）

    查看代码 
     package com.***;
 
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
/**
 * @description: excel导出
 * @author: ***
 * @date: 2022/6/21
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ExcelExport {
    /**
     * 字段名称
     */
    String value();
 
    /**
     * 导出排序先后: 数字越小越靠前（默认按Java类字段顺序导出）
     */
    int sort() default 0;
 
    /**
     * 导出映射，格式如：0-未知;1-男;2-女
     */
    String kv() default "";
 
    /**
     * 导出模板示例值（有值的话，直接取该值，不做映射）
     */
    String example() default "";
 
}

    3.ExcelImport（导入Excel用）

    查看代码 
     package com.***;
 
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
/**
 * @description: excel导入
 * @author: ***
 * @date: 2022/6/21
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ExcelImport {
    /**
     * 字段名称
     */
    String value();
 
    /**
     * 导出映射，格式如：0-未知;1-男;2-女
     */
    String kv() default "";
 
    /**
     * 是否为必填字段（默认为非必填）
     */
    boolean required() default false;
 
    /**
     * 最大长度（默认255）
     */
    int maxLength() default 255;
 
    /**
     * 导入唯一性验证（多个字段则取联合验证）
     */
    boolean unique() default false;
 
}

    4.ExcelUtils

    查看代码 
     package com.***;
import com.***.utils.DateUtil;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.***.uitl.StringUtils;
import org.apache.poi.hssf.usermodel.HSSFDataValidation;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.usermodel.ClientAnchor.AnchorType;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.ss.util.CellRangeAddressList;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFClientAnchor;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.multipart.MultipartFile;
 
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.net.URL;
import java.net.URLEncoder;
import java.text.NumberFormat;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.Map.Entry;
import java.util.regex.Pattern;
 
 
/**
 * @description: 导出报表util
 * @author: ***
 * @date: 2022/6/21
 */
public class ExcelUtils {
    public static final String ROW_MERGE = "row_merge";
    public static final String COLUMN_MERGE = "column_merge";
    private static final String XLSX = ".xlsx";
    private static final String XLS = ".xls";
    private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
    private static final String ROW_NUM = "rowNum";
    private static final String ROW_DATA = "rowData";
    private static final String ROW_TIPS = "rowTips";
    private static final int CELL_OTHER = 0;
    private static final int CELL_ROW_MERGE = 1;
    private static final int CELL_COLUMN_MERGE = 2;
    private static final int IMG_HEIGHT = 30;
    private static final int IMG_WIDTH = 30;
    private static final char LEAN_LINE = '/';
    private static final int BYTES_DEFAULT_LENGTH = 10240;
    private static final NumberFormat NUMBER_FORMAT = NumberFormat.getNumberInstance();
 
    public static  List readFile(File file, Class clazz) throws Exception {
        JSONArray array = readFile(file);
        return getBeanList(array, clazz);
    }
 
    public static  List readMultipartFile(MultipartFile mFile, Class clazz) throws Exception {
        JSONArray array = readMultipartFile(mFile);
        return getBeanList(array, clazz);
    }
 
    public static JSONArray readFile(File file) throws Exception {
        return readExcel(null, file);
    }
 
    public static JSONArray readMultipartFile(MultipartFile mFile) throws Exception {
        return readExcel(mFile, null);
    }
 
    public static Map readFileManySheet(File file) throws Exception {
        return readExcelManySheet(null, file);
    }
 
    public static Map readFileManySheet(MultipartFile file) throws Exception {
        return readExcelManySheet(file, null);
    }
 
    private static  List getBeanList(JSONArray array, Class clazz) throws Exception {
        List list = new ArrayList<>();
        Map uniqueMap = new HashMap<>(16);
        for (int i = 0; i < array.size(); i++) {
            list.add(getBean(clazz, array.getJSONObject(i), uniqueMap));
        }
        return list;
    }
 
    /**
     * 获取每个对象的数据
     */
    private static  T getBean(Class c, JSONObject obj, Map uniqueMap) throws Exception {
        T t = c.newInstance();
        Field[] fields = c.getDeclaredFields();
        List errMsgList = new ArrayList<>();
        boolean hasRowTipsField = false;
        StringBuilder uniqueBuilder = new StringBuilder();
        int rowNum = 0;
        for (Field field : fields) {
            // 行号
            if (field.getName().equals(ROW_NUM)) {
                rowNum = obj.getInteger(ROW_NUM);
                field.setAccessible(true);
                field.set(t, rowNum);
                continue;
            }
            // 是否需要设置异常信息
            if (field.getName().equals(ROW_TIPS)) {
                hasRowTipsField = true;
                continue;
            }
            // 原始数据
            if (field.getName().equals(ROW_DATA)) {
                field.setAccessible(true);
                field.set(t, obj.toString());
                continue;
            }
            // 设置对应属性值
            setFieldValue(t, field, obj, uniqueBuilder, errMsgList);
        }
        // 数据唯一性校验
        if (uniqueBuilder.length() > 0) {
            if (uniqueMap.containsValue(uniqueBuilder.toString())) {
                Set rowNumKeys = uniqueMap.keySet();
                for (Integer num : rowNumKeys) {
                    if (uniqueMap.get(num).equals(uniqueBuilder.toString())) {
                        errMsgList.add(String.format("数据唯一性校验失败,(%s)与第%s行重复)", uniqueBuilder, num));
                    }
                }
            } else {
                uniqueMap.put(rowNum, uniqueBuilder.toString());
            }
        }
        // 失败处理
        if (errMsgList.isEmpty() && !hasRowTipsField) {
            return t;
        }
        StringBuilder sb = new StringBuilder();
        int size = errMsgList.size();
        for (int i = 0; i < size; i++) {
            if (i == size - 1) {
                sb.append(errMsgList.get(i));
            } else {
                sb.append(errMsgList.get(i)).append(";");
            }
        }
        // 设置错误信息
        for (Field field : fields) {
            if (field.getName().equals(ROW_TIPS)) {
                field.setAccessible(true);
                field.set(t, sb.toString());
            }
        }
        return t;
    }
 
    private static  void setFieldValue(T t, Field field, JSONObject obj, StringBuilder uniqueBuilder, List errMsgList) {
        // 获取 ExcelImport 注解属性
        ExcelImport annotation = field.getAnnotation(ExcelImport.class);
        if (annotation == null) {
            return;
        }
        String cname = annotation.value();
        if (cname.trim().length() == 0) {
            return;
        }
        // 获取具体值
        String val = null;
        if (obj.containsKey(cname)) {
            val = getString(obj.getString(cname));
        }
        if (val == null) {
            return;
        }
        field.setAccessible(true);
        // 判断是否必填
        boolean require = annotation.required();
        if (require && val.isEmpty()) {
            errMsgList.add(String.format("[%s]不能为空", cname));
            return;
        }
        // 数据唯一性获取
        boolean unique = annotation.unique();
        if (unique) {
            if (uniqueBuilder.length() > 0) {
                uniqueBuilder.append("--").append(val);
            } else {
                uniqueBuilder.append(val);
            }
        }
        // 判断是否超过最大长度
        int maxLength = annotation.maxLength();
        if (maxLength > 0 && val.length() > maxLength) {
            errMsgList.add(String.format("[%s]长度不能超过%s个字符(当前%s个字符)", cname, maxLength, val.length()));
        }
        // 判断当前属性是否有映射关系
        LinkedHashMap kvMap = getKvMap(annotation.kv());
        if (!kvMap.isEmpty()) {
            boolean isMatch = false;
            for (String key : kvMap.keySet()) {
                if (kvMap.get(key).equals(val)) {
                    val = key;
                    isMatch = true;
                    break;
                }
            }
            if (!isMatch) {
                errMsgList.add(String.format("[%s]的值不正确(当前值为%s)", cname, val));
                return;
            }
        }
        // 其余情况根据类型赋值
        String fieldClassName = field.getType().getSimpleName();
        try {
            if ("String".equalsIgnoreCase(fieldClassName)) {
                field.set(t, val);
            } else if ("boolean".equalsIgnoreCase(fieldClassName)) {
                field.set(t, Boolean.valueOf(val));
            } else if ("int".equalsIgnoreCase(fieldClassName) || "Integer".equals(fieldClassName)) {
                try {
                    field.set(t, Integer.valueOf(val));
                } catch (NumberFormatException e) {
                    errMsgList.add(String.format("[%s]的值格式不正确(当前值为%s)", cname, val));
                }
            } else if ("double".equalsIgnoreCase(fieldClassName)) {
                field.set(t, Double.valueOf(val));
            } else if ("long".equalsIgnoreCase(fieldClassName)) {
                field.set(t, Long.valueOf(val));
            } else if ("BigDecimal".equalsIgnoreCase(fieldClassName)) {
                if (StringUtils.isEmpty(val)) {
                    field.set(t, new BigDecimal(0));
                } else {
                    field.set(t, new BigDecimal(val));
                }
            } else if ("Date".equalsIgnoreCase(fieldClassName)) {
                field.set(t, DateUtil.getDate(val, DateUtil.YYYYMMDDHHMMSS));
            } else {
                field.set(t, val);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    private static Map readExcelManySheet(MultipartFile mFile, File file) throws IOException {
        Workbook book = getWorkbook(mFile, file);
        if (book == null) {
            return Collections.emptyMap();
        }
        Map map = new LinkedHashMap<>();
        for (int i = 0; i < book.getNumberOfSheets(); i++) {
            Sheet sheet = book.getSheetAt(i);
            JSONArray arr = readSheet(sheet);
            map.put(sheet.getSheetName(), arr);
        }
        book.close();
        return map;
    }
 
    private static JSONArray readExcel(MultipartFile mFile, File file) throws IOException {
        Workbook book = getWorkbook(mFile, file);
        if (book == null) {
            return new JSONArray();
        }
        JSONArray array = readSheet(book.getSheetAt(0));
        book.close();
        return array;
    }
 
    private static Workbook getWorkbook(MultipartFile mFile, File file) throws IOException {
        boolean fileNotExist = (file == null || !file.exists());
        if (mFile == null && fileNotExist) {
            return null;
        }
        // 解析表格数据
        InputStream in;
        String fileName;
        if (mFile != null) {
            // 上传文件解析
            in = mFile.getInputStream();
            fileName = getString(mFile.getOriginalFilename()).toLowerCase();
        } else {
            // 本地文件解析
            in = new FileInputStream(file);
            fileName = file.getName().toLowerCase();
        }
        Workbook book;
        if (fileName.endsWith(XLSX)) {
            book = new XSSFWorkbook(in);
        } else if (fileName.endsWith(XLS)) {
            POIFSFileSystem poifsFileSystem = new POIFSFileSystem(in);
            book = new HSSFWorkbook(poifsFileSystem);
        } else {
            return null;
        }
        in.close();
        return book;
    }
 
    private static JSONArray readSheet(Sheet sheet) {
        // 首行下标
        int rowStart = sheet.getFirstRowNum();
        // 尾行下标
        int rowEnd = sheet.getLastRowNum();
        // 获取表头行
        Row headRow = sheet.getRow(rowStart);
        if (headRow == null) {
            return new JSONArray();
        }
        int cellStart = headRow.getFirstCellNum();
        int cellEnd = headRow.getLastCellNum();
        Map keyMap = new HashMap<>();
        for (int j = cellStart; j < cellEnd; j++) {
            // 获取表头数据
            String val = getCellValue(headRow.getCell(j));
            if (val != null && val.trim().length() != 0) {
                keyMap.put(j, val);
            }
        }
        // 如果表头没有数据则不进行解析
        if (keyMap.isEmpty()) {
            return (JSONArray) Collections.emptyList();
        }
        // 获取每行JSON对象的值
        JSONArray array = new JSONArray();
        // 如果首行与尾行相同，表明只有一行，返回表头数据
        if (rowStart == rowEnd) {
            JSONObject obj = new JSONObject();
            // 添加行号
            obj.put(ROW_NUM, 1);
            for (int i : keyMap.keySet()) {
                obj.put(keyMap.get(i), "");
            }
            array.add(obj);
            return array;
        }
        for (int i = rowStart + 1; i <= rowEnd; i++) {
            Row eachRow = sheet.getRow(i);
            JSONObject obj = new JSONObject();
            // 添加行号
            obj.put(ROW_NUM, i + 1);
            StringBuilder sb = new StringBuilder();
            for (int k = cellStart; k < cellEnd; k++) {
                if (eachRow != null) {
                    String val = getCellValue(eachRow.getCell(k));
                    // 所有数据添加到里面，用于判断该行是否为空
                    sb.append(val);
                    obj.put(keyMap.get(k), val);
                }
            }
            if (sb.length() > 0) {
                array.add(obj);
            }
        }
        return array;
    }
 
    private static String getCellValue(Cell cell) {
        // 空白或空
        if (cell == null || cell.getCellType() == CellType.BLANK) {
            return "";
        }
        // String类型
        if (cell.getCellType() == CellType.STRING) {
            String val = cell.getStringCellValue();
            if (val == null || val.trim().length() == 0) {
                return "";
            }
            return val.trim();
        }
        // 数字类型
        if (cell.getCellType() == CellType.NUMERIC) {
            String s = cell.getNumericCellValue() + "";
            // 去掉尾巴上的小数点0
            if (Pattern.matches(".*\\.0*", s)) {
                return s.split("\\.")[0];
            } else {
                return s.trim();
            }
        }
        // 布尔值类型
        if (cell.getCellType() == CellType.BOOLEAN) {
            return cell.getBooleanCellValue() + "";
        }
        // 错误类型
        return cell.getCellFormula();
    }
 
    public static  void exportTemplate(HttpServletResponse response, String fileName, Class clazz, String dateFormat) {
        exportTemplate(response, fileName, fileName, clazz, false, dateFormat);
    }
 
    public static  void exportTemplate(HttpServletResponse response, String fileName, String sheetName,
                                          Class clazz, String dateFormat) {
        exportTemplate(response, fileName, sheetName, clazz, false, dateFormat);
    }
 
    public static  void exportTemplate(HttpServletResponse response, String fileName, Class clazz,
                                          boolean isContainExample, String dateFormat) {
        exportTemplate(response, fileName, fileName, clazz, isContainExample, dateFormat);
    }
 
    public static  void exportTemplate(HttpServletResponse response, String fileName, String sheetName,
                                          Class clazz, boolean isContainExample, String dateFormat) {
        // 获取表头字段
        List headFieldList = getExcelClassFieldList(clazz);
        // 获取表头数据和示例数据
        List> sheetDataList = new ArrayList<>();
        List headList = new ArrayList<>();
        List exampleList = new ArrayList<>();
        Map> selectMap = new LinkedHashMap<>();
        for (int i = 0; i < headFieldList.size(); i++) {
            ExcelClassField each = headFieldList.get(i);
            headList.add(each.getName());
            exampleList.add(each.getExample());
            LinkedHashMap kvMap = each.getKvMap();
            if (kvMap != null && kvMap.size() > 0) {
                selectMap.put(i, new ArrayList<>(kvMap.values()));
            }
        }
        sheetDataList.add(headList);
        if (isContainExample) {
            sheetDataList.add(exampleList);
        }
        // 导出数据
        export(response, fileName, sheetName, sheetDataList, selectMap, dateFormat);
    }
 
    private static  List getExcelClassFieldList(Class clazz) {
        // 解析所有字段
        Field[] fields = clazz.getDeclaredFields();
        boolean hasExportAnnotation = false;
        Map> map = new LinkedHashMap<>();
        List sortList = new ArrayList<>();
        for (Field field : fields) {
            ExcelClassField cf = getExcelClassField(field);
            if (cf.getHasAnnotation() == 1) {
                hasExportAnnotation = true;
            }
            int sort = cf.getSort();
            if (map.containsKey(sort)) {
                map.get(sort).add(cf);
            } else {
                List list = new ArrayList<>();
                list.add(cf);
                sortList.add(sort);
                map.put(sort, list);
            }
        }
        Collections.sort(sortList);
        // 获取表头
        List headFieldList = new ArrayList<>();
        if (hasExportAnnotation) {
            for (Integer sort : sortList) {
                for (ExcelClassField cf : map.get(sort)) {
                    if (cf.getHasAnnotation() == 1) {
                        headFieldList.add(cf);
                    }
                }
            }
        } else {
            headFieldList.addAll(map.get(0));
        }
        return headFieldList;
    }
 
    private static  ExcelClassField getExcelClassField(Field field) {
        ExcelClassField cf = new ExcelClassField();
        String fieldName = field.getName();
        cf.setFieldName(fieldName);
        ExcelExport annotation = field.getAnnotation(ExcelExport.class);
        // 无 ExcelExport 注解情况
        if (annotation == null) {
            cf.setHasAnnotation(0);
            cf.setName(fieldName);
            cf.setSort(0);
            return cf;
        }
        // 有 ExcelExport 注解情况
        cf.setHasAnnotation(1);
        cf.setName(annotation.value());
        String example = getString(annotation.example());
        if (!example.isEmpty()) {
            if (isNumeric(example)) {
                cf.setExample(Double.valueOf(example));
            } else {
                cf.setExample(example);
            }
        } else {
            cf.setExample("");
        }
        cf.setSort(annotation.sort());
        // 解析映射
        String kv = getString(annotation.kv());
        cf.setKvMap(getKvMap(kv));
        return cf;
    }
 
    private static LinkedHashMap getKvMap(String kv) {
        LinkedHashMap kvMap = new LinkedHashMap<>();
        if (kv.isEmpty()) {
            return kvMap;
        }
        String[] kvs = kv.split(";");
        if (kvs.length == 0) {
            return kvMap;
        }
        for (String each : kvs) {
            String[] eachKv = getString(each).split("-");
            if (eachKv.length != 2) {
                continue;
            }
            String k = eachKv[0];
            String v = eachKv[1];
            if (k.isEmpty() || v.isEmpty()) {
                continue;
            }
            kvMap.put(k, v);
        }
        return kvMap;
    }
 
    /**
     * 导出表格到本地
     *
     * @param file      本地文件对象
     * @param sheetData 导出数据
     */
    public static void exportFile(File file, List> sheetData, String dateFormat) {
        if (file == null) {
            System.out.println("文件创建失败");
            return;
        }
        if (sheetData == null) {
            sheetData = new ArrayList<>();
        }
        Map>> map = new HashMap<>();
        map.put(file.getName(), sheetData);
        export(null, file, file.getName(), map, null, dateFormat);
    }
 
    /**
     * 导出表格到本地
     *
     * @param       导出数据类似，和K类型保持一致
     * @param filePath 文件父路径（如：D:/doc/excel/）
     * @param fileName 文件名称（不带尾缀，如：学生表）
     * @param list     导出数据
     * @throws IOException IO异常
     */
    public static  File exportFile(String filePath, String fileName, List list, String dateFormat) throws IOException {
        File file = getFile(filePath, fileName);
        List> sheetData = getSheetData(list);
        exportFile(file, sheetData, dateFormat);
        return file;
    }
 
    /**
     * 获取文件
     *
     * @param filePath filePath 文件父路径（如：D:/doc/excel/）
     * @param fileName 文件名称（不带尾缀，如：用户表）
     * @return 本地File文件对象
     */
    private static File getFile(String filePath, String fileName) throws IOException {
        String dirPath = getString(filePath);
        String fileFullPath;
        if (dirPath.isEmpty()) {
            fileFullPath = fileName;
        } else {
            // 判定文件夹是否存在，如果不存在，则级联创建
            File dirFile = new File(dirPath);
            if (!dirFile.exists()) {
                dirFile.mkdirs();
            }
            // 获取文件夹全名
            if (dirPath.endsWith(String.valueOf(LEAN_LINE))) {
                fileFullPath = dirPath + fileName + XLSX;
            } else {
                fileFullPath = dirPath + LEAN_LINE + fileName + XLSX;
            }
        }
        System.out.println(fileFullPath);
        File file = new File(fileFullPath);
        if (!file.exists()) {
            file.createNewFile();
        }
        return file;
    }
 
    private static  List> getSheetData(List list) {
        // 获取表头字段
        List excelClassFieldList = getExcelClassFieldList(list.get(0).getClass());
        List headFieldList = new ArrayList<>();
        List headList = new ArrayList<>();
        Map headFieldMap = new HashMap<>();
        for (ExcelClassField each : excelClassFieldList) {
            String fieldName = each.getFieldName();
            headFieldList.add(fieldName);
            headFieldMap.put(fieldName, each);
            headList.add(each.getName());
        }
        // 添加表头名称
        List> sheetDataList = new ArrayList<>();
        sheetDataList.add(headList);
        // 获取表数据
        for (T t : list) {
            Map fieldDataMap = getFieldDataMap(t);
            Set fieldDataKeys = fieldDataMap.keySet();
            List rowList = new ArrayList<>();
            for (String headField : headFieldList) {
                if (!fieldDataKeys.contains(headField)) {
                    continue;
                }
                Object data = fieldDataMap.get(headField);
                if (data == null) {
                    rowList.add("");
                    continue;
                }
                // 超防止过11位的数字自动转换为科学计数法
                String string = data.toString();
                if (isNumeric(string) && string.length() > 11) {
                    data = new BigDecimal(string).toPlainString();
                }
 
                ExcelClassField cf = headFieldMap.get(headField);
                // 判断是否有映射关系
                LinkedHashMap kvMap = cf.getKvMap();
                if (kvMap == null || kvMap.isEmpty()) {
                    rowList.add(data);
                    continue;
                }
                String val = kvMap.get(data.toString());
                if (val == null) {
                    rowList.add(data);
                    continue;
                }
                if (isNumeric(val)) {
                    rowList.add(Double.valueOf(val));
                } else {
                    rowList.add(val);
                }
            }
            sheetDataList.add(rowList);
        }
        return sheetDataList;
    }
 
    private static  Map getFieldDataMap(T t) {
        Map map = new HashMap<>();
        Field[] fields = t.getClass().getDeclaredFields();
        try {
            for (Field field : fields) {
                String fieldName = field.getName();
                field.setAccessible(true);
                Object object = field.get(t);
                map.put(fieldName, object);
            }
        } catch (IllegalArgumentException | IllegalAccessException e) {
            e.printStackTrace();
        }
        return map;
    }
 
    public static void exportEmpty(HttpServletResponse response, String fileName, String dateFormat) {
        List> sheetDataList = new ArrayList<>();
        List headList = new ArrayList<>();
        headList.add("导出无数据");
        sheetDataList.add(headList);
        export(response, fileName, sheetDataList, dateFormat);
    }
 
    public static void export(HttpServletResponse response, String fileName, List> sheetDataList, String dateFormat) {
        export(response, fileName, fileName, sheetDataList, null, dateFormat);
    }
 
    public static void exportManySheet(HttpServletResponse response, String fileName, Map>> sheetMap, String dateFormat) {
        export(response, null, fileName, sheetMap, null, dateFormat);
    }
 
 
    public static void export(HttpServletResponse response, String fileName, String sheetName,
                              List> sheetDataList, String dateFormat) {
        export(response, fileName, sheetName, sheetDataList, null, dateFormat);
    }
 
    public static void export(HttpServletResponse response, String fileName, String sheetName,
                              List> sheetDataList, Map> selectMap, String dateFormat) {
 
        Map>> map = new HashMap<>();
        map.put(sheetName, sheetDataList);
        export(response, null, fileName, map, selectMap, dateFormat);
    }
 
    public static  void export(HttpServletResponse response, String fileName, List list, Class template) {
        String dateFormat = DATE_FORMAT;
        // list 是否为空
        boolean lisIsEmpty = list == null || list.isEmpty();
        // 如果模板数据为空，且导入的数据为空，则导出空文件
        if (template == null && lisIsEmpty) {
            exportEmpty(response, fileName, dateFormat);
            return;
        }
        // 如果 list 数据，则导出模板数据
        if (lisIsEmpty) {
            exportTemplate(response, fileName, template, dateFormat);
            return;
        }
        // 导出数据
        List> sheetDataList = getSheetData(list);
        export(response, fileName, sheetDataList, dateFormat);
    }
 
    public static  void export(HttpServletResponse response, String fileName, List list, Class template, String dateFormat) {
        // list 是否为空
        boolean lisIsEmpty = list == null || list.isEmpty();
        // 如果模板数据为空，且导入的数据为空，则导出空文件
        if (template == null && lisIsEmpty) {
            exportEmpty(response, fileName, dateFormat);
            return;
        }
        // 如果 list 数据，则导出模板数据
        if (lisIsEmpty) {
            exportTemplate(response, fileName, template, dateFormat);
            return;
        }
        // 导出数据
        List> sheetDataList = getSheetData(list);
        export(response, fileName, sheetDataList, dateFormat);
    }
 
    public static void export(HttpServletResponse response, String fileName, List> sheetDataList, Map> selectMap, String dateFormat) {
        export(response, fileName, fileName, sheetDataList, selectMap, dateFormat);
    }
 
    private static void export(HttpServletResponse response, File file, String fileName,
                               Map>> sheetMap, Map> selectMap, String dateFormat) {
        // 整个 Excel 表格 book 对象
        SXSSFWorkbook book = new SXSSFWorkbook();
        // 每个 Sheet 页
        Set>>> entries = sheetMap.entrySet();
        for (Entry>> entry : entries) {
            List> sheetDataList = entry.getValue();
            Sheet sheet = book.createSheet(entry.getKey());
            Drawing patriarch = sheet.createDrawingPatriarch();
            // 设置表头背景色（灰色）
            CellStyle headStyle = book.createCellStyle();
            headStyle.setFillForegroundColor(IndexedColors.GREY_80_PERCENT.index);
            headStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
            headStyle.setAlignment(HorizontalAlignment.CENTER);
            headStyle.setFillForegroundColor(IndexedColors.GREY_25_PERCENT.index);
            // 设置表身背景色（默认色）
            CellStyle rowStyle = book.createCellStyle();
            rowStyle.setAlignment(HorizontalAlignment.CENTER);
            rowStyle.setVerticalAlignment(VerticalAlignment.CENTER);
            //创建一个DataFormat对象
            DataFormat format = book.createDataFormat();
            rowStyle.setDataFormat(format.getFormat("@"));
            // 设置表格列宽度（默认为15个字节）
            sheet.setDefaultColumnWidth(15);
            // 创建合并算法数组
            int rowLength = sheetDataList.size();
            int columnLength = sheetDataList.get(0).size();
            int[][] mergeArray = new int[rowLength][columnLength];
            for (int i = 0; i < sheetDataList.size(); i++) {
                // 每个 Sheet 页中的行数据
                Row row = sheet.createRow(i);
                List rowList = sheetDataList.get(i);
                for (int j = 0; j < rowList.size(); j++) {
                    // 每个行数据中的单元格数据
                    Object o = rowList.get(j);
                    int v = 0;
                    if (o instanceof URL) {
                        // 如果要导出图片的话, 链接需要传递 URL 对象
                        setCellPicture(book, row, patriarch, i, j, (URL) o);
                    } else {
                        Cell cell = row.createCell(j);
                        if (i == 0) {
                            // 第一行为表头行，采用灰色底背景
                            v = setCellValue(cell, o, headStyle, dateFormat);
                        } else {
                            // 其他行为数据行，默认白底色
                            v = setCellValue(cell, o, rowStyle, dateFormat);
                        }
                    }
                    mergeArray[i][j] = v;
                }
            }
            // 合并单元格
            mergeCells(sheet, mergeArray);
            // 设置下拉列表
            setSelect(sheet, selectMap);
        }
        // 写数据
        if (response != null) {
            // 前端导出
            try {
                write(response, book, fileName);
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            // 本地导出
            FileOutputStream fos;
            try {
                fos = new FileOutputStream(file);
                ByteArrayOutputStream ops = new ByteArrayOutputStream();
                book.write(ops);
                fos.write(ops.toByteArray());
                fos.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
 
    /**
     * 合并当前Sheet页的单元格
     *
     * @param sheet      当前 sheet 页
     * @param mergeArray 合并单元格算法
     */
    private static void mergeCells(Sheet sheet, int[][] mergeArray) {
        // 横向合并
        for (int x = 0; x < mergeArray.length; x++) {
            int[] arr = mergeArray[x];
            boolean merge = false;
            int y1 = 0;
            int y2 = 0;
            for (int y = 0; y < arr.length; y++) {
                int value = arr[y];
                if (value == CELL_COLUMN_MERGE) {
                    if (!merge) {
                        y1 = y;
                    }
                    y2 = y;
                    merge = true;
                } else {
                    merge = false;
                    if (y1 > 0) {
                        sheet.addMergedRegion(new CellRangeAddress(x, x, (y1 - 1), y2));
                    }
                    y1 = 0;
                    y2 = 0;
                }
            }
            if (y1 > 0) {
                sheet.addMergedRegion(new CellRangeAddress(x, x, (y1 - 1), y2));
            }
        }
        // 纵向合并
        int xLen = mergeArray.length;
        int yLen = mergeArray[0].length;
        for (int y = 0; y < yLen; y++) {
            boolean merge = false;
            int x1 = 0;
            int x2 = 0;
            for (int x = 0; x < xLen; x++) {
                int value = mergeArray[x][y];
                if (value == CELL_ROW_MERGE) {
                    if (!merge) {
                        x1 = x;
                    }
                    x2 = x;
                    merge = true;
                } else {
                    merge = false;
                    if (x1 > 0) {
                        sheet.addMergedRegion(new CellRangeAddress((x1 - 1), x2, y, y));
                    }
                    x1 = 0;
                    x2 = 0;
                }
            }
            if (x1 > 0) {
                sheet.addMergedRegion(new CellRangeAddress((x1 - 1), x2, y, y));
            }
        }
    }
 
    private static void write(HttpServletResponse response, SXSSFWorkbook book, String fileName) throws IOException {
        /*response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        String name = new String(fileName.getBytes("GBK"), "ISO8859_1") + XLSX;
        response.addHeader("Content-Disposition", "attachment;filename=" + name);*/
        /*String formFileName = new String(fileName.getBytes(StandardCharsets.UTF_8), StandardCharsets.ISO_8859_1);
        response.setHeader("Content-Disposition", String.format("attachment; filename=\"%s\";", formFileName));
        response.setContentType("multipart/form-data");
        response.setCharacterEncoding("UTF-8");*/
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        assert attributes != null;
        HttpServletRequest request = attributes.getRequest();
        response.setContentType("multipart/form-data;charset=UTF-8");
        String userAgent = request.getHeader("USER-AGENT");
        try {
            if (userAgent.contains("MSIE") || userAgent.contains("Edge")) {// IE浏览器
                fileName = URLEncoder.encode(fileName, "UTF8");
            } else if (userAgent.contains("Mozilla")) {// google,火狐浏览器
                fileName = new String(fileName.getBytes(), "ISO8859-1");
            } else {
                fileName = URLEncoder.encode(fileName, "UTF8");// 其他浏览器
            }
            response.setHeader("Content-disposition", "attachment; filename=" + fileName);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        ServletOutputStream out = response.getOutputStream();
        book.write(out);
        out.flush();
        out.close();
    }
 
    private static int setCellValue(Cell cell, Object o, CellStyle style, String dateFormat) {
        // 设置样式
        cell.setCellStyle(style);
        // 数据为空时
        if (o == null) {
            cell.setCellType(CellType.STRING);
            cell.setCellValue("");
            return CELL_OTHER;
        }
        // 是否为字符串
        if (o instanceof String) {
            String s = o.toString();
            if (isNumeric(s)) {
                if (s.length() > 11) {
                    cell.setCellType(CellType.STRING);
                    cell.setCellValue(s);
                    return CELL_OTHER;
                } else {
                    cell.setCellType(CellType.NUMERIC);
                    cell.setCellValue(Double.parseDouble(s));
                    return CELL_OTHER;
                }
            } else {
                cell.setCellType(CellType.STRING);
                cell.setCellValue(s);
            }
            if (s.equals(ROW_MERGE)) {
                return CELL_ROW_MERGE;
            } else if (s.equals(COLUMN_MERGE)) {
                return CELL_COLUMN_MERGE;
            } else {
                return CELL_OTHER;
            }
        }
        // 是否为字符串
        if (o instanceof Integer || o instanceof Long || o instanceof Double || o instanceof Float) {
            cell.setCellType(CellType.NUMERIC);
            cell.setCellValue(Double.parseDouble(o.toString()));
            return CELL_OTHER;
        }
        // 是否为Boolean
        if (o instanceof Boolean) {
            cell.setCellType(CellType.BOOLEAN);
            cell.setCellValue((Boolean) o);
            return CELL_OTHER;
        }
        // 如果是BigDecimal，则默认3位小数
        if (o instanceof BigDecimal) {
            cell.setCellType(CellType.NUMERIC);
            cell.setCellValue(((BigDecimal) o).setScale(3, RoundingMode.HALF_UP).doubleValue());
            return CELL_OTHER;
        }
        // 如果是Date数据，则显示格式化数据
        if (o instanceof Date) {
            cell.setCellType(CellType.STRING);
            cell.setCellValue(formatDate((Date) o, dateFormat));
            return CELL_OTHER;
        }
        // 如果是其他，则默认字符串类型
        cell.setCellType(CellType.STRING);
        cell.setCellValue(o.toString());
        return CELL_OTHER;
    }
 
    private static void setCellPicture(SXSSFWorkbook wb, Row sr, Drawing patriarch, int x, int y, URL url) {
        // 设置图片宽高
        sr.setHeight((short) (IMG_WIDTH * IMG_HEIGHT));
        // （jdk1.7版本try中定义流可自动关闭）
        try (InputStream is = url.openStream(); ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
            byte[] buff = new byte[BYTES_DEFAULT_LENGTH];
            int rc;
            while ((rc = is.read(buff, 0, BYTES_DEFAULT_LENGTH)) > 0) {
                outputStream.write(buff, 0, rc);
            }
            // 设置图片位置
            XSSFClientAnchor anchor = new XSSFClientAnchor(0, 0, 0, 0, y, x, y + 1, x + 1);
            // 设置这个，图片会自动填满单元格的长宽
            anchor.setAnchorType(AnchorType.MOVE_AND_RESIZE);
            patriarch.createPicture(anchor, wb.addPicture(outputStream.toByteArray(), HSSFWorkbook.PICTURE_TYPE_JPEG));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    private static String formatDate(Date date, String dateFormat) {
        if (date == null) {
            return "";
        }
        if (dateFormat == null) {
            dateFormat = DATE_FORMAT;
        }
        SimpleDateFormat format = new SimpleDateFormat(dateFormat);
        return format.format(date);
    }
 
    private static void setSelect(Sheet sheet, Map> selectMap) {
        if (selectMap == null || selectMap.isEmpty()) {
            return;
        }
        Set>> entrySet = selectMap.entrySet();
        for (Entry> entry : entrySet) {
            int y = entry.getKey();
            List list = entry.getValue();
            if (list == null || list.isEmpty()) {
                continue;
            }
            String[] arr = new String[list.size()];
            for (int i = 0; i < list.size(); i++) {
                arr[i] = list.get(i);
            }
            DataValidationHelper helper = sheet.getDataValidationHelper();
            CellRangeAddressList addressList = new CellRangeAddressList(1, 65000, y, y);
            DataValidationConstraint dvc = helper.createExplicitListConstraint(arr);
            DataValidation dv = helper.createValidation(dvc, addressList);
            if (dv instanceof HSSFDataValidation) {
                dv.setSuppressDropDownArrow(false);
            } else {
                dv.setSuppressDropDownArrow(true);
                dv.setShowErrorBox(true);
            }
            sheet.addValidationData(dv);
        }
    }
 
    private static boolean isNumeric(String str) {
        if ("0.0".equals(str)) {
            return true;
        }
        if ("".equals(str)) {
            return false;
        }
 
        for (int i = str.length(); --i >= 0; ) {
            if (!Character.isDigit(str.charAt(i))) {
                return false;
            }
        }
        return true;
    }
 
    private static String getString(String s) {
        if (s == null) {
            return "";
        }
        if (s.isEmpty()) {
            return s;
        }
        return s.trim();
    }
 
}


    三、相关业务代码
    

    1.service层
    

        /*** 车运运单信息导出*/
    List exportBillInfo(List billIdList);
    

    2.impl实现类
    

            实现类里的代码，需求各位根据自己的业务场景进行改动，将需要导出的数据查询出来
    

    
查看代码

         @Override
    public List exportBillInfo(List billIdList) {
        if (StringUtils.isEmpty(billIdList)) {
            throw new ServiceException("车辆运单ID不能为空");
        }
        BillDto billDto = new BillDto();
        billDto.setBillIdList(billIdList);
        List billList = billFacadeService.queryBillList(billDto);
        if (StringUtils.isEmpty(billList)) {
            billList = new ArrayList<>();
        }
        return InvoiceWrapper.instance.convertTo(billList);
    }
    

    

    3.controller层
    

            controller层的代码需要注意的是：
    

    1.因为导出Excel一般都是通过浏览器进行下载的，所以入参中需要加入HttpServletResponse
    

    2.调用封装的工具类ExcelUtils中的export方法就可以了
    

    
查看代码

         /**
     * 车运运单信息导出
     */
    @Log
    @PostMapping("/exportBillInfo")
    public void exportBillInfo(@RequestBody @Valid BillListDto dto, HttpServletResponse response) {
        List list = invoiceFacadeService.exportBillInfo(dto.getBillIdList());
        ExcelUtils.export(response, "车运运单信息", list, ExportBillVo.class);
    }
    

    

    最终导出的Excel文件：
    

    

    

                    
                

                
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                    原文地址：https://www.cnblogs.com/wyj-java/p/16747200.html
                
    •