JAVA Excel读写

目录

一.Apache poi读写

1.pom

2.Excel读写

3.Excel读写运行测试

4.综合运用写入Excel

 二.EasyExcel

1.pom

2.异步读取代码

3.写入代码

三.excel格式化写入指定位置 合并单元格等

1.pom

2.model格式

3.工具类


Excel支持两种格式的读写功能 分别为xlsx和xls版本

一.Apache poi读写

        Java领域解析、生成Excel比较有名的框架有Apache poi。但他们都存在一个严重的问题就是非常的耗内存。如果你的系统并发量不大的话可能还行,但是一旦并发上来后一定会OOM或者JVM频繁的full gc

1.pom

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>4.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>4.1.2</version>
        </dependency>

2.Excel读写

import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.NumberToTextConverter;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.LinkedList;
import java.util.List;

public class ExcelUtil {

    public ReaderExcel.Model readExcel(String path) throws IOException {
        ReaderExcel excelUtil = new ReaderExcel();
        ReaderExcel.Model read = excelUtil.read(path);
        return read;
    }

    public void writerExcel(String path, List<List<String>> data) {
        List<String> head = data.remove(0);
        writerExcel(path, "首页", head, data);
    }

    public void writerExcel(String path, List<String> head, List<List<String>> data) {
        writerExcel(path, "首页", head, data);
    }

    public void writerExcel(String path, String sheetName, List<String> head, List<List<String>> data) {
        ExcelUtil excelUtil = null;
        if (path.endsWith(".xls")) {
            excelUtil = new WriterXLS();
        } else if (path.endsWith(".xlsx")) {
            excelUtil = new WriterXLSX();
        }
        excelUtil.createSheet(sheetName);//创建sheet页
        excelUtil.createHead(head);//设置表头
        excelUtil.createContent(data);//设置内容
        excelUtil.writeToFile(path);//写入文件xlsx/xls
    }

    /**
     * 禁止外部访问create方法
     * 创建Sheet页
     *
     * @param sheetName
     */
    protected void createSheet(String sheetName) {
        System.out.println("父createSheet");
    }

    /**
     * 创建字段
     *
     * @param headList
     */
    protected void createHead(List<String> headList) {
        System.out.println("createSheet");
    }


    /**
     * 创建内容
     *
     * @param contentList
     */
    protected void createContent(List<List<String>> contentList) {
        System.out.println("createSheet");
    }

    /**
     * 写入文件
     *
     * @param filePath
     */
    protected void writeToFile(String filePath) {
    }

    private class WriterXLS extends ExcelUtil {
        private HSSFWorkbook hssfWorkbook;
        private HSSFSheet hssfSheet;
        private HSSFRow hssfRow;
        private HSSFCell hssfCell;

        @Override
        protected void createSheet(String sheetName) {
            hssfWorkbook = new HSSFWorkbook();
            hssfSheet = hssfWorkbook.createSheet(sheetName);
        }

        @Override
        protected void createHead(List<String> headList) {
            //创建表头,也就是第一行
            if (hssfSheet == null) hssfWorkbook.createSheet("首页");
            hssfRow = hssfSheet.createRow(0);
            for (int i = 0; i < headList.size(); i++) {
                hssfCell = hssfRow.createCell(i);
                hssfCell.setCellValue(headList.get(i));
            }
        }

        @Override
        protected void createContent(List<List<String>> contentList) {
            //创建表内容,从第二行开始
            for (int i = 0; i < contentList.size(); i++) {
                hssfRow = hssfSheet.createRow(i + 1);
                for (int j = 0; j < contentList.get(i).size(); j++) {
                    hssfRow.createCell(j).setCellValue(contentList.get(i).get(j));
                }
            }
        }

        @Override
        protected void writeToFile(String filePath) {
            File file = new File(filePath);
            try {
                hssfWorkbook.write(new FileOutputStream(file));
                hssfWorkbook.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private class WriterXLSX extends ExcelUtil {
        private XSSFWorkbook xssfWorkbook;
        private XSSFSheet xssfSheet;
        private XSSFRow xssfRow;
        private XSSFCell xssfCell;

        @Override
        protected void createSheet(String sheetName) {
            xssfWorkbook = new XSSFWorkbook();
            xssfSheet = xssfWorkbook.createSheet(sheetName);
        }

        @Override
        protected void createHead(List<String> headList) {
            //创建表头,也就是第一行
            if (xssfSheet == null) xssfWorkbook.createSheet("首页");
            xssfRow = xssfSheet.createRow(0);
            for (int i = 0; i < headList.size(); i++) {
                xssfCell = xssfRow.createCell(i);
                xssfCell.setCellValue(headList.get(i));
            }
        }

        @Override
        protected void createContent(List<List<String>> contentList) {
            //创建表内容,从第二行开始
            for (int i = 0; i < contentList.size(); i++) {
                xssfRow = xssfSheet.createRow(i + 1);
                for (int j = 0; j < contentList.get(i).size(); j++) {
                    xssfRow.createCell(j).setCellValue(contentList.get(i).get(j));
                }
            }
        }

        @Override
        protected void writeToFile(String filePath) {
            File file = new File(filePath);
            //将文件保存到指定的位置
            try {
                xssfWorkbook.write(new FileOutputStream(file));
                xssfWorkbook.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }


    }


    private class ReaderExcel extends ExcelUtil {
        /**
         * 读取Excel文件
         *
         * @param filePath 文件地址
         * @return
         */
        private Model read(String filePath) throws IOException {
            FileInputStream inputStream = null;
            Model dataLst = null;
            try {
                inputStream = new FileInputStream(filePath);
                Workbook wb = null;
                if (filePath.endsWith(ExcelType.XLSX.suffix)) {
                    wb = new XSSFWorkbook(inputStream);
                } else if (filePath.endsWith(ExcelType.XLS.suffix)) {
                    wb = new HSSFWorkbook(inputStream);
                } else {
                    //不支持
                }
                dataLst = readDate(wb);
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (inputStream != null) inputStream.close();
            }
            return dataLst;
        }

        /**
         * 读取数据
         *
         * @param wb
         * @return
         */
        private Model readDate(Workbook wb) {
            Sheet sheet = wb.getSheetAt(0);//得到第一个shell
            int totalRows = sheet.getPhysicalNumberOfRows();//得到Excel的行数
            if (totalRows == 0) return null;
            Row headRow = sheet.getRow(0);
            int totalCells = sheet.getRow(0).getPhysicalNumberOfCells();//得到Excel的列数
            List<String> head = new LinkedList<>();
            List<List<String>> dataList = new LinkedList<>();
            Model model = new Model();
            model.head = head;
            model.data = dataList;
            for (int i = 0; i < totalCells; i++) head.add(headRow.getCell(i).getStringCellValue());
            for (int index = 1; index < totalRows; index++) {//循环Excel的行
                Row row = sheet.getRow(index);
                if (row == null) continue;
                List<String> rowList = new LinkedList<>();
                dataList.add(rowList);//保存第r行的第c列
                for (int field = 0; field < totalCells; field++) {//循环Excel的列
                    Cell cell = row.getCell(field);
                    String cellValue = null == cell ? "" : getCellValue(cell);// 以下是判断数据的类型
                    rowList.add(cellValue);
                }
            }
            return model;
        }

        /**
         * 解析一行内容
         *
         * @param cell
         * @return
         */
        private String getCellValue(Cell cell) {
            String cellValue;
            switch (cell.getCellTypeEnum()) {
                case NUMERIC:
                    cellValue = (cell != null && HSSFDateUtil.isCellDateFormatted(cell)) ? new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(cell.getDateCellValue()) : NumberToTextConverter.toText(cell.getNumericCellValue());
                    break;
                case STRING:
                    cellValue = cell.getStringCellValue();
                    break;
                case BOOLEAN:
                    cellValue = cell.getBooleanCellValue() + "";
                    break;
                case FORMULA:
                    cellValue = cell.getCellFormula() + "";
                    break;
                case BLANK:
                    cellValue = "";
                    break;
                case ERROR:
                    cellValue = "非法字符";
                    break;
                default:
                    cellValue = "未知类型";
                    break;
            }
            return cellValue;
        }
    }

    /**
     * excel数据存储对象
     */
    public class Model {
        public List<String> head;//字段
        public List<List<String>> data;//数据
    }

    enum ExcelType {
        XLSX("xlsx", 2007),
        XLS("xls", 2003);
        public String suffix;
        public int type;

        ExcelType(String suffix, int type) {
            this.suffix = suffix;
            this.type = type;
        }
    }
}

3.Excel读写运行测试

import com.ExcelUtil;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class MyExcelTest {
    public static void main(String[] args) throws IOException {
        //读取测试
        String filePath = "C:\\Users\\Administrator\\Desktop\\数据\\住建局.xls";
        ExcelUtil excelUtil = new ExcelUtil();
        ExcelUtil.Model model = excelUtil.readExcel(filePath);
        System.out.println(model.head);
        for (List<String> dataLine : model.data) {
            System.out.println(dataLine);
        }
        //写入测试
        List<String> headList = new ArrayList<>();
        headList.add("name");
        headList.add("age");
        List<List<String>> contentList = getData();//内容测试数据
        ExcelUtil writeToExcel = new ExcelUtil();
        String saveFile = "C:\\Users\\Administrator\\Desktop\\数据\\work.xlsx";
        writeToExcel.writerExcel(saveFile,headList,contentList);//写入文件xlsx/xls
    }
    //写入测试数据
    static List<List<String>> getData() {
        List<List<String>> contentList = new ArrayList<>();
        List<String> line1 = new ArrayList<>();
        line1.add("张三");
        line1.add("11");
        List<String> line2 = new ArrayList<>();
        line2.add("李四");
        line2.add("12");
        contentList.add(line1);
        contentList.add(line2);
        return contentList;
    }
}

4.综合运用写入Excel

package com.libii.business.util.excel.model;

import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import java.io.FileOutputStream;
public class ExcelTest {
    /**
     * 格式化写入excel文件
     *
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        HSSFWorkbook workbook = new HSSFWorkbook();//创建excel对象
        HSSFCellStyle centerStyle = workbook.createCellStyle();//设置样式
        centerStyle.setBorderBottom(BorderStyle.THIN); //下边框
        centerStyle.setBorderLeft(BorderStyle.THIN);//左边框
        centerStyle.setBorderTop(BorderStyle.THIN);//上边框
        centerStyle.setBorderRight(BorderStyle.THIN);//右边框
        centerStyle.setAlignment(HorizontalAlignment.CENTER);  // 设置水平和垂直居中对齐
        centerStyle.setVerticalAlignment(VerticalAlignment.CENTER);//设置居中对其
        centerStyle.setWrapText(true);//设置自动换行
        String filePath = "C:\\Users\\admin\\Desktop\\输出文件\\1.xls";//输出文件地址
        String nameUnit = "Sheet1";//excel当前页码名称
        Sheet sheet = workbook.createSheet(nameUnit); // 创建一个工作表
        sheet.autoSizeColumn(0);//设置文本自适应
        setValue(sheet, centerStyle, 0, 0, 0, 0, "测试");
        setValue(sheet, centerStyle, 1, 1, 0, 1, "测试");
        FileOutputStream out = new FileOutputStream(filePath);
        workbook.write(out);
        out.close();
        workbook.close();
    }


    /**
     * 合并单元格并设置样式和值
     *
     * @param sheet    excel当前页
     * @param style    样式
     * @param firstRow 合并起始行
     * @param lastRow  合并借宿行
     * @param firstCol 合并起始列
     * @param lastCol  合并结束列
     * @param value    值
     */
    public static void setValue(Sheet sheet, HSSFCellStyle style, int firstRow, int lastRow, int firstCol, int lastCol, String value) {
        if (firstRow == lastRow && firstCol == lastCol) {
            setUnitValue(sheet, style, firstRow, firstCol, value);
        } else {
            merge(sheet, style, firstRow, lastRow, firstCol, lastCol, value);
        }
    }

    /**
     * 设置单元格样式和值
     *
     * @param sheet    excel当前页
     * @param style    样式
     * @param firstRow 行
     * @param firstCol 列
     * @param value    值
     */
    private static void setUnitValue(Sheet sheet, HSSFCellStyle style, int firstRow, int firstCol, String value) {
        Row row = sheet.getRow(firstRow);
        if (row == null) row = sheet.createRow(firstRow);
        Cell cell = row.getCell(firstCol);
        if (cell == null) cell = row.createCell(firstCol);
        if (value != null) cell.setCellValue(value);
        if (style != null) cell.setCellStyle(style);
        //设置格子的高度和宽度
        //row.setHeight(500);//设置高度
        //int columnIndex = cell.getColumnIndex();
        //sheet.setColumnWidth(columnIndex, 5000);
    }

    /**
     * 合并单元格并设置样式和值
     *
     * @param sheet    excel当前页
     * @param style    样式
     * @param firstRow 合并起始行
     * @param lastRow  合并借宿行
     * @param firstCol 合并起始列
     * @param lastCol  合并结束列
     * @param value    值
     */
    private static void merge(Sheet sheet, HSSFCellStyle style, int firstRow, int lastRow, int firstCol, int lastCol, String value) {
        sheet.addMergedRegion(new CellRangeAddress(firstRow, lastRow, firstCol, lastCol));
        if (style != null) {//设置样式
            for (int i = firstRow; i <= lastRow; i++) {
                Row row = sheet.getRow(i);//3, 3, 0, 23
                if (row == null) row = sheet.createRow(i);
                for (int j = firstCol; j <= lastCol; j++) {
                    Cell cell = row.getCell(j);
                    if (cell == null) cell = row.createCell(j);
                    cell.setCellStyle(style);
                }
            }
        }


        Row row = sheet.getRow(firstRow);
        Cell cell = row.getCell(firstCol);
        if (value != null && cell != null) {
            cell.setCellValue(value);
        }
        //设置格子的高度和宽度
        //row.setHeight(500);//设置高度
        //int columnIndex = cell.getColumnIndex();
        //sheet.setColumnWidth(columnIndex, 5000);
    }
}

 二.EasyExcel

        阿里巴巴开源的一个excel处理框架EasyExcel,以使用简单、节省内存著称。EasyExcel能大大减少占用内存的主要原因是在解析Excel时没有将文件数据一次性全部加载到内存中,而是从磁盘上一行行读取数据,逐个解析

1.pom

        <!--自动set与get忽略-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>
        <!--EXCEL解析-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>3.3.2</version>
        </dependency>
        <dependency><!--excel内部缺失的包commons-compress版本冲突可以排除其他版本引入这个版本 -->
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-compress</artifactId>
            <version>1.26.1</version>
        </dependency>

2.异步读取代码

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelReader;
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.excel.metadata.data.ReadCellData;
import com.alibaba.excel.read.metadata.ReadSheet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

public class ExcelReadUtil extends AnalysisEventListener<Map<Integer, String>> {
    final private Logger logger = LoggerFactory.getLogger(this.getClass());//日志对象

    //读取的数据量
    private int sum = 0;
    //消费队列最大等待次数
    int maxWaitFrequency = 5;
    //读取文件的绝对路径
    private final String fileName;
    //Excel字段头信息<列位置(从0开始),列内容>
    private Map<Integer, String> headMap;
    //转换excel的列名称为系统需要的列名称 <列内容,系统需要的内容> 示例: <姓名,name>
    private final Map<String, String> kvMapper;
    //读取过程中是否异常
    private boolean readError = false;
    //读取是否完成
    private boolean readSuccess = false;
    //存储读取数据的队列
    private final BlockingQueue<Map<String, String>> queue;

    //内存变量,读取完毕需要删除
    private FileInputStream inputStream = null;
    private ExcelReader excelReader = null;


    public ExcelReadUtil(String fileName) throws Exception {
        this(fileName, null);
    }

    /**
     * 初始化读取工具类
     *
     * @param fileName 读取的excel文件名称
     * @param kvMapper 字段映射信息 excel字段在前 系统字段在后
     * @throws Exception 异常信息
     */
    public ExcelReadUtil(String fileName, Map<String, String> kvMapper) throws Exception {
        if (!new File(fileName).exists()) throw new FileNotFoundException("文件不存在: " + fileName);
        this.kvMapper = kvMapper;
        this.fileName = fileName;
        readExcel();
        this.queue = new LinkedBlockingQueue<>(50000);//队列
    }

    /**
     * 读取excel文件初始化
     */
    private void readExcel() {
        new Thread(() -> {
            try {
                inputStream = new FileInputStream(this.fileName);
                excelReader = EasyExcel.read(inputStream, this).build();//把前端传来的文件转成输入流
                ReadSheet readSheet = EasyExcel.readSheet(0).build();//指定读取哪一个sheet
                excelReader.read(readSheet);//开始读取
                excelReader.finish();
            } catch (Exception e) {
                logger.error("构造excel处理对象异常", e);
            } finally {
                close(excelReader);//读的时候会创建临时文件,需要主动关闭
                close(inputStream);
            }
        }).start();
    }

    /**
     * 开始读取
     *
     * @param headReadCellMap 读取的head字段信息
     * @param context         上下文对象
     */
    @Override
    public void invokeHead(Map<Integer, ReadCellData<?>> headReadCellMap, AnalysisContext context) {
        //获取excel中的头字段
        Map<Integer, String> headMap = headReadCellMap.entrySet().stream()//读取excel的第一行作为表头,过滤空的字段名称
                .filter(entry -> entry.getValue().getStringValue() != null)
                .filter(entry -> !entry.getValue().getStringValue().trim().isEmpty())
                .collect(Collectors.toMap(Map.Entry::getKey, unit -> unit.getValue().getStringValue()));
        if (this.kvMapper != null) {
            Map<Integer, String> headMapTmp = new HashMap<>();
            for (Map.Entry<Integer, String> entry : headMap.entrySet()) {
                Integer excelIndex = entry.getKey();
                String excelHeadValue = entry.getValue();
                String systemHeadValue = this.kvMapper.get(excelHeadValue);
                if (systemHeadValue == null) continue;//不存在的记录,不写入
                headMapTmp.put(excelIndex, systemHeadValue);
            }
            headMap = headMapTmp;
        }
        this.headMap = headMap;
    }

    /**
     * 循环读取文件行内容
     *
     * @param data    当前读取的一行数据
     * @param context 上下文对象
     */
    public void invoke(Map<Integer, String> data, AnalysisContext context) {
        if (this.readError) return;//读取数据出现异常,直接跳过
        Map<String, String> line = new HashMap<>();
        for (Map.Entry<Integer, String> entry : this.headMap.entrySet()) {
            String fieldName = entry.getValue();
            String value = data.get(entry.getKey());
            line.put(fieldName, value);//读取excel文件转化为json,一行一个json对象
        }
        queuePut(line);
    }


    /**
     * 消费数据
     *
     * @return 消费的一条数据
     */
    public Map<String, String> queueGetData() throws Exception {
        int waitFrequency = 0;
        while (true) {
            boolean status = this.readSuccess;
            Map<String, String> line = this.queue.poll(1, TimeUnit.SECONDS); // 等待1秒
            if (line != null) return line;
            if (status) return null;
            waitFrequency++;
            if (waitFrequency > this.maxWaitFrequency) throw new Exception("消费数据失败");
        }
    }


    /**
     * 读取结束用于释放资源
     *
     * @param context 上下文对象
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        readSuccess = true;
    }


    /**
     * 关闭资源
     *
     * @param obj 资源对象
     */
    private void close(AutoCloseable obj) {
        if (obj == null) return;
        try {
            obj.close();
        } catch (Exception e) {
            logger.error("处理excel关闭连接异常,连接类型: [{}]", obj.getClass().getName(), e);
        }
    }

    public void close() {//主动关闭
        close(excelReader);
        close(inputStream);
    }

    /**
     * 读取的数据写入队列
     *
     * @param line 读取写入数据到队列
     */
    private void queuePut(Map<String, String> line) {
        try {
            this.queue.put(line);
            this.sum++;
        } catch (InterruptedException e) {
            this.readError = true;
        }
    }

    /**
     * 获取读取的累计数据量
     *
     * @return 累计数据量
     */
    public int getDataSum() {
        return this.sum;
    }


    public static void main(String[] args) throws Exception {
        String fileName = "C:\\Users\\admin\\Desktop\\data\\1.xls";
        ExcelReadUtil excelListener = new ExcelReadUtil(fileName);//该监听器一行行将文件读取到内存
//        ExcelListener excelListener = new ExcelListener(fileName,kvMapper);//kvMapper代表excel文件的头字段与转化后头字段的映射关系
        while (true) {
            Map<String, String> map = excelListener.queueGetData();
            if (map == null) break;
            System.out.println(map);
        }
        System.out.println("结束");
        System.out.println("累计数据量: " + excelListener.getDataSum());
    }
}

3.写入代码


import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.write.metadata.WriteSheet;
import org.yn.util.resource.ResourceUtil;

import java.util.*;
import java.util.stream.Collectors;

public class ExcelWriterUtil implements AutoCloseable {
    private final Map<String, List<String>> headerMap;//多页写入的头字段列表
    private final Map<String, WriteSheet> sheetMap = new HashMap<>();//excel的分页对象
    private List<String> header;//字段的写入顺序
    private final ExcelWriter excelWriter;//excel写入对象

    public ExcelWriterUtil(String fileName, List<String> header) {
        this.excelWriter = EasyExcel.write(fileName).build();
        this.headerMap = new HashMap<>();
        this.header = header == null ? new ArrayList<>() : header;
    }

    public ExcelWriterUtil(String fileName) {
        this.excelWriter = EasyExcel.write(fileName).build();
        this.headerMap = new HashMap<>();
        this.header = new ArrayList<>();
    }


    @Override
    public void close() {
        this.excelWriter.close();
    }

    /**
     * 写入完成前先刷新否则别的进程读不到
     */
    public void finish() {
        this.excelWriter.finish();
    }


    /**
     * 写入一行数据
     *
     * @param name     写入的sheet名称
     * @param dataLine 需要写入的数据
     */
    public void write(String name, Map<String, String> dataLine) {
        WriteSheet writeSheet = getWriteSheet(name);
        if (!this.headerMap.containsKey(name)) {
            if (header.isEmpty()) header = new ArrayList<>(dataLine.keySet());//设置字段
            this.headerMap.put(name, header);//写入head
            List<List<String>> collect = header.stream().map(Arrays::asList).collect(Collectors.toList());
            writeSheet.setHead(collect);
        }
        List<Object> mapperDataLine = this.headerMap.get(name).stream().map(dataLine::get).collect(Collectors.toList());
        this.excelWriter.write(Collections.singletonList(mapperDataLine), writeSheet);
    }

    /**
     * 写入多行数据
     *
     * @param name      写入的sheet名称
     * @param dataBatch 需要写入的数据
     */
    public void writeBatch(String name, List<Map<String, String>> dataBatch) {
        if (dataBatch.isEmpty()) return;
        WriteSheet writeSheet = getWriteSheet(name);
        if (!this.headerMap.containsKey(name)) {
            if (header.isEmpty()) header = new ArrayList<>(dataBatch.get(0).keySet());//设置字段
            this.headerMap.put(name, header);
            List<List<String>> collect = header.stream().map(Arrays::asList).collect(Collectors.toList());
            writeSheet.setHead(collect);
        }
        List<String> header = this.headerMap.get(name);
        List<List<Object>> mapperDataLine = new ArrayList<>();
        for (Map<String, String> kvLineData : dataBatch) {
            List<Object> dataLine = new ArrayList<>();
            for (String key : header) {
                Object value = kvLineData.get(key);
                dataLine.add(value);
            }
            mapperDataLine.add(dataLine);
        }
        this.excelWriter.write(mapperDataLine, writeSheet);
    }

    /**
     * 获取写入的sheet对象
     *
     * @param name sheet的名称
     * @return 返回sheet对象
     */
    private WriteSheet getWriteSheet(String name) {
        if (!this.sheetMap.containsKey(name)) {
            this.sheetMap.put(name, EasyExcel.writerSheet(name).build());
        }
        return this.sheetMap.get(name);
    }

    public static void main(String[] args) {
        String fileName = "C:\\Users\\admin\\Desktop\\1\\11.xlsx";
        ExcelWriterUtil writerExcel = new ExcelWriterUtil(fileName);
//        ExcelWriterUtil writerExcel = new ExcelWriterUtil(fileName,header);//手动设置头字段的顺序
        List<Map<String, String>> listData = new ArrayList<>();
        Map<String, String> map1 = new HashMap<>();
        Map<String, String> map2 = new HashMap<>();
        map1.put("姓名", "张三");
        map1.put("年龄", "123");
        map2.put("姓名", "张四");
        map2.put("年龄", "1234");
        listData.add(map1);
        listData.add(map2);
        writerExcel.write("分页1", map1);
        writerExcel.write("分页1", map1);
        writerExcel.write("分页2", map2);
        writerExcel.writeBatch("批量分页3", listData);
        writerExcel.finish();
        ResourceUtil.close(writerExcel);
    }
}

三.excel格式化写入指定位置 合并单元格等

1.pom

        <dependency><!-- 自动get/set等 -->
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
            <scope>provided</scope>
        </dependency>
        <dependency><!-- 处理poi依赖冲突问题 -->
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-math3</artifactId>
            <version>3.6.1</version>
        </dependency>
        <dependency><!-- excel处理依赖 -->
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>4.1.2</version>
        </dependency>

2.model格式

import lombok.Data;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;

@Data
public class UnitModel {

    private Object value;
    private HSSFCellStyle style;
    private int firstRow;//起始行
    private int lastRow;//结束行
    private int firstCol;//起始列
    private int lastCol;//结束列
    final int left = 0;//向右移动的格子
    final int down = 0;//向下移动的格子

    public UnitModel(int firstRow, int lastRow, int firstCol, int lastCol, HSSFCellStyle style, Object value) {
        this.firstRow = firstRow + down;
        this.lastRow = lastRow + down;
        this.firstCol = firstCol + left;
        this.lastCol = lastCol + left;
        this.style = style;
        this.value = value;
    }

    public UnitModel(int firstRow, int lastRow, int firstCol, int lastCol, HSSFCellStyle style) {
        this(firstRow, lastRow, firstCol, lastCol, style, null);
    }

    public UnitModel(int firstRow, int lastRow, int firstCol, int lastCol, String value) {
        this(firstRow, lastRow, firstCol, lastCol, null, value);
    }

    public UnitModel(int firstRow, int lastRow, int firstCol, int lastCol) {
        this(firstRow, lastRow, firstCol, lastCol, null, null);
    }

    public UnitModel(int firstRow, int firstCol, HSSFCellStyle style, String value) {
        this.firstRow = firstRow;
        this.firstCol = firstCol;
        this.style = style;
        this.value = value;
    }
}

3.工具类

import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.ss.util.NumberToTextConverter;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * 写入数据到excel
 */
public class ExcelUtil {
    /**
     * 读取Excel文件
     *
     * @param fileName 文件名称
     * @return 文件内容
     * @throws IOException 异常信息
     */
    public static List<List<String>> readData(String fileName) throws IOException {
        List<List<String>> data = new ArrayList<>();
        FileInputStream fis = null;
        Workbook workbook = null;
        try {
            fis = new FileInputStream(fileName);
            workbook = new HSSFWorkbook(fis);
            Sheet sheet = workbook.getSheetAt(0);
            Iterator<Row> iterator = sheet.iterator();
            Row head = iterator.next();
            List<String> headLine = new ArrayList<>();
            data.add(headLine);
            for (Cell cell : head) {
                String cellValue = getCellValue(cell);
                headLine.add(cellValue);
            }
            while (iterator.hasNext()) {
                Row row = iterator.next();
                List<String> unit = new ArrayList<>();
                data.add(unit);
                for (int i = 0; i < headLine.size(); i++) {
                    Cell cell = row.getCell(i);
                    String cellValue = getCellValue(cell);
                    unit.add(cellValue);
                }
            }

        } finally {
            close(fis);
            close(workbook);
        }
        return data;
    }

    /**
     * 读取Excel文件
     *
     * @param fileName 文件名称
     * @param rows     读取的行数
     * @return 文件内容
     * @throws IOException 异常信息
     */
    public static List<List<String>> readData(String fileName, int rows) throws IOException {
        List<List<String>> data = new ArrayList<>();
        FileInputStream fis = null;
        Workbook workbook = null;
        try {

            fis = new FileInputStream(fileName);
            workbook = new HSSFWorkbook(fis);
            Sheet sheet = workbook.getSheetAt(0);
            Iterator<Row> iterator = sheet.iterator();
            while (iterator.hasNext()) {
                Row row = iterator.next();
                List<String> unit = new ArrayList<>();
                data.add(unit);
                for (int i = 0; i < rows; i++) {
                    Cell cell = row.getCell(i);
                    String cellValue = getCellValue(cell);
                    unit.add(cellValue);
                }
            }
        } finally {
            close(fis);
            close(workbook);
        }
        return data;
    }


    public static void writerSheet(HSSFWorkbook workbook, Map<String, List<UnitModel>> allData) {
        for (Map.Entry<String, List<UnitModel>> entry : allData.entrySet()) {
            String name = entry.getKey();
            if (name == null) name = "未知";
            List<UnitModel> dataList = entry.getValue();
            Sheet sheet = workbook.createSheet(name); // 创建一个工作表
            sheet.autoSizeColumn(0);
            for (UnitModel unitModel : dataList) {
                setValue(sheet, unitModel);
            }
        }
    }

    /**
     * 读取内容
     */
    private static String getCellValue(Cell cell) {
        if (cell == null) return "";
        String cellValue;
        switch (cell.getCellTypeEnum()) {
            case NUMERIC:
                cellValue = (cell != null && HSSFDateUtil.isCellDateFormatted(cell)) ? new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(cell.getDateCellValue()) : NumberToTextConverter.toText(cell.getNumericCellValue());
                break;
            case STRING:
                cellValue = cell.getStringCellValue();
                break;
            case BOOLEAN:
                cellValue = cell.getBooleanCellValue() + "";
                break;
            case FORMULA:
                cellValue = cell.getCellFormula() + "";
                break;
            case BLANK:
                cellValue = "";
                break;
            case ERROR:
                cellValue = "非法字符";
                break;
            default:
                cellValue = "未知类型";
                break;
        }
        return cellValue;
    }

    public static void setValue(Sheet sheet, UnitModel model) {
        if (model.getFirstRow() == model.getLastRow() && model.getFirstCol() == model.getLastCol()) {
            setUnitValue(sheet, model);
        } else {
            merge(sheet, model);
        }
    }

    public static void setUnitValue(Sheet sheet, UnitModel model) {
        HSSFCellStyle style = model.getStyle();
        int firstRow = model.getFirstRow();
        int firstCol = model.getFirstCol();
        Object value = model.getValue();
        Row row = sheet.getRow(firstRow);
        if (row == null) row = sheet.createRow(firstRow);
        Cell cell = row.getCell(firstCol);
        if (cell == null) cell = row.createCell(firstCol);
        if (value != null) cell.setCellValue(String.valueOf(value));
        if (style != null) cell.setCellStyle(style);
    }

    private static void merge(Sheet sheet, UnitModel model) {
        HSSFCellStyle style = model.getStyle();
        int firstRow = model.getFirstRow();
        int lastRow = model.getLastRow();
        int firstCol = model.getFirstCol();
        int lastCol = model.getLastCol();
        Object value = model.getValue();
        sheet.addMergedRegion(new CellRangeAddress(firstRow, lastRow, firstCol, lastCol));

        for (int i = firstRow; i <= lastRow; i++) {
            Row row = sheet.getRow(i);//3, 3, 0, 23
            if (row == null) row = sheet.createRow(i);
            for (int j = firstCol; j <= lastCol; j++) {
                Cell cell = row.getCell(j);
                if (cell == null) cell = row.createCell(j);
                if (style != null) cell.setCellStyle(style);
            }
        }
        Row row = sheet.getRow(firstRow);
        Cell cell = row.getCell(firstCol);
        //设置cell的宽度
        if (value != null) {
            cell.setCellValue(String.valueOf(value));
            cell.setCellStyle(style);
        }
    }

    private static void close(AutoCloseable closeable) {
        try {
            if (closeable != null) closeable.close();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) throws IOException {
        String pathFileName = "C:\\Users\\admin\\Desktop\\1.xlsx";
        if (new File(pathFileName).exists()) new File(pathFileName).delete();
        List<UnitModel> unitModels = new ArrayList<>();
        unitModels.add(new UnitModel(0, 0, 0, 2, "镇政策数量前五"));//(起始行,结束行,起始列,结束列,字段里面的内容), 跨行自动合并, 被使用的单元格不能再一次写入数据
        unitModels.add(new UnitModel(1, 1, 0, 0, "镇名称"));
        unitModels.add(new UnitModel(1, 1, 1, 1, "数量"));//模拟数据
        Map<String, List<UnitModel>> allData = new HashMap<>();
        allData.put("第一页", unitModels);
        HSSFWorkbook workbook = null;
        FileOutputStream out = null;
        try {
            workbook = new HSSFWorkbook();
            ExcelUtil.writerSheet(workbook, allData);
            out = new FileOutputStream(pathFileName);
            workbook.write(out);
            List<List<String>> lists = readData(pathFileName);
            System.out.println(lists);
        } finally {
            close(out);
            close(workbook);
        }
    }
}

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