Implementation of easyexcel's function of merging cells with the same content and dynamic title

         I believe many students have used EasyExcel Done export function , Now Q Also encountered a demand , Is to export Excel Vertical cells with the same contents in the are merged , Then you need to give Excel Set dynamic title , Then adjust the format definition , The implementation process of this function is now recorded , Give the students a reference to avoid stepping on the same pit .

        jar Package version ：

One 、 Original version

The result of the export ：

  Corresponding entity class code ：

import com.alibaba.excel.annotation.ExcelProperty;
import com.alibaba.excel.annotation.write.style.ColumnWidth;
import com.alibaba.excel.annotation.write.style.ContentLoopMerge;
import com.alibaba.excel.annotation.write.style.ContentRowHeight;
import com.alibaba.excel.annotation.write.style.HeadRowHeight;
import lombok.*;

import java.io.Serializable;

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Data
@ContentRowHeight(30)
@HeadRowHeight(40)
@ColumnWidth(25)
public class StudentExportVo implements Serializable {

    private static final long serialVersionUID = -5809782578272943999L;

    @ExcelProperty(value = " School ", order = 1)
    @ContentLoopMerge(eachRow = 3)
    private String school;

    @ExcelProperty(value = " full name ", order = 2)
    private String name;

    @ExcelProperty(value = " Gender ", order = 3)
    private String sex;

    @ExcelProperty(value = " Age ", order = 4)
    private String age;

    @ExcelProperty(value = " City ", order = 5)
    private String city;

    @ExcelProperty(value = " remarks ", order = 6)
    private String remarks;

    }

Corresponding business code ：

@ApiOperation(value = " Export student information ", notes = " Export student information ")
@PostMapping("/exportStudent")
public void exportStudent(@RequestBody String str, HttpServletResponse response) {
    List<StudentExportVo> list = this.getStudentExportVos();
    ExcelUtils.writeExcel(response, StudentExportVo.class, list, " Export student information ", "sheet1");
}
// Data manufacturing 
private List<StudentExportVo> getStudentExportVos() {
    List<StudentExportVo> list = new ArrayList<>();
    StudentExportVo v1 = new StudentExportVo();
    v1.setSchool(" Peking University, ");
    v1.setName(" Zhang San ");
    v1.setSex(" male ");
    v1.setAge("20");
    v1.setCity(" Beijing ");
    v1.setRemarks(" nothing ");
    list.add(v1);
    StudentExportVo v2 = new StudentExportVo();
    v2.setSchool(" Peking University, ");
    v2.setName(" Li Si ");
    v2.setSex(" male ");
    v2.setAge("22");
    v2.setCity(" Shanghai ");
    v2.setRemarks(" nothing ");
    list.add(v2);
    StudentExportVo v3 = new StudentExportVo();
    v3.setSchool(" Peking University, ");
    v3.setName(" Wang Wu ");
    v3.setSex(" Woman ");
    v3.setAge("22");
    v3.setCity(" Qingdao ");
    v3.setRemarks(" nothing ");
    list.add(v3);
    StudentExportVo v4 = new StudentExportVo();
    v4.setSchool(" Tsinghua University ");
    v4.setName(" Zhao Liu ");
    v4.setSex(" Woman ");
    v4.setAge("21");
    v4.setCity(" Chongqing ");
    v4.setRemarks(" nothing ");
    list.add(v4);
    StudentExportVo v5 = new StudentExportVo();
    v5.setSchool(" Wuhan University ");
    v5.setName(" Wang Qiang ");
    v5.setSex(" male ");
    v5.setAge("24");
    v5.setCity(" Changsha ");
    v5.setRemarks(" nothing ");
    list.add(v5);
    StudentExportVo v6 = new StudentExportVo();
    v6.setSchool(" Wuhan University ");
    v6.setName(" Zhao Yan ");
    v6.setSex(" Woman ");
    v6.setAge("21");
    v6.setCity(" Shenzhen ");
    v6.setRemarks(" nothing ");
    list.add(v6);
    StudentExportVo v7 = new StudentExportVo();
    v7.setSchool(" Xiamen University ");
    v7.setName(" six thousand ");
    v7.setSex(" Woman ");
    v7.setAge("21");
    v7.setCity(" Guangzhou ");
    v7.setRemarks(" nothing ");
    list.add(v7);
    return list;
}

Two 、 Use the annotated version

The result of the export ：

   Corresponding entity class code ：

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Data
@ContentRowHeight(30)
@HeadRowHeight(40)
@ColumnWidth(25)
public class StudentExportVo implements Serializable {

    private static final long serialVersionUID = -5809782578272943999L;

    @ExcelProperty(value = {" Student information "," School "}, order = 1)
    @ContentLoopMerge(eachRow = 3)
    private String school;

    @ExcelProperty(value = {" Student information "," full name "}, order = 2)
    private String name;

    @ExcelProperty(value = {" Student information "," Gender "}, order = 3)
    private String sex;

    @ExcelProperty(value = {" Student information "," Age "}, order = 4)
    private String age;

    @ExcelProperty(value = {" Student information "," City "}, order = 5)
    private String city;

    @ExcelProperty(value = {" Student information "," remarks "}, order = 6)
    private String remarks;

    }

Corresponding business code ： ditto

Be careful ：

@ContentLoopMerge(eachRow = 3) You can merge cells , But it merges by the specified number of rows , It is not possible to merge the same content

@ExcelProperty(value = {" Student information "," remarks "}, It can realize multiple titles , But the title is fixed , It's not dynamic

3、 ... and 、 Custom modification

The result of the export ：

Corresponding entity class code ：

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Data
@ContentRowHeight(30)
@HeadRowHeight(40)
@ColumnWidth(25)
public class StudentExportVo implements Serializable {

    private static final long serialVersionUID = -5809782578272943999L;

    @ExcelProperty(value = {" Student information "," School "}, order = 1)
    //@ContentLoopMerge(eachRow = 3)
    private String school;

    @ExcelProperty(value = {" Student information "," full name "}, order = 2)
    private String name;

    @ExcelProperty(value = {" Student information "," Gender "}, order = 3)
    private String sex;

    @ExcelProperty(value = {" Student information "," Age "}, order = 4)
    private String age;

    @ExcelProperty(value = {" Student information "," City "}, order = 5)
    private String city;

    @ExcelProperty(value = {" Student information "," remarks "}, order = 6)
    private String remarks;

}

Corresponding business code ：

@ApiOperation(value = " Export student information ", notes = " Export student information ")
    @PostMapping("/exportStudent")
    public void exportStudent(@RequestBody String dynamicTitle, HttpServletResponse response) {
        List<StudentExportVo> list = this.getStudentExportVos();
        try {
            String fileName = " Student information ";
            fileName = URLEncoder.encode(fileName, "UTF-8");
            response.setContentType("application/json;charset=utf-8");
            response.setCharacterEncoding("utf-8");
            response.addHeader("Pargam", "no-cache");
            response.addHeader("Cache-Control", "no-cache");
            response.setHeader("Content-Disposition", "attachment;filename=" + fileName + ".xlsx");
            ServletOutputStream output = response.getOutputStream();
            // Columns to be merged 
            int[] mergeColumeIndex = {0};
            //  Start merging after the second line 
            int mergeRowIndex = 2;
            // Set dynamic title 
            List<List<String>> headers = this.getHeaders(" Student information " + dynamicTitle);
            //  The head's strategy 
            WriteCellStyle headWriteCellStyle = new WriteCellStyle();
            //  The background is set to white 
            headWriteCellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());
            headWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
            /*WriteFont headWriteFont = new WriteFont();
            headWriteFont.setFontHeightInPoints((short)20);
            headWriteCellStyle.setWriteFont(headWriteFont);*/

            //  Content strategy 
            WriteCellStyle contentWriteCellStyle = new WriteCellStyle();
            //  You need to specify  FillPatternType  by FillPatternType.SOLID_FOREGROUND  Otherwise, the background color cannot be displayed . The head defaults  FillPatternType So you don't have to specify 
            //contentWriteCellStyle.setFillPatternType(FillPatternType.SOLID_FOREGROUND);
            //  The background is green 
            //contentWriteCellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());
            // Set up   Word wrap 
            contentWriteCellStyle.setWrapped(true);
            // Set up   Vertical center 
            contentWriteCellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
            // Set up   Horizontal center 
            contentWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);
            /*WriteFont contentWriteFont = new WriteFont();
            //  font size 
            contentWriteFont.setFontHeightInPoints((short)20);
            contentWriteCellStyle.setWriteFont(contentWriteFont);*/
            //  The strategy is   The head is the pattern of the head   Content is the style of content   Other strategies can be implemented by themselves 
            HorizontalCellStyleStrategy horizontalCellStyleStrategy =
                    new HorizontalCellStyleStrategy(headWriteCellStyle, contentWriteCellStyle);

            EasyExcel.write(output, StudentExportVo.class)
                    .sheet(" Student information ")
                    .head(headers)
                    .registerWriteHandler(new ExcelMergeHandler(mergeRowIndex, mergeColumeIndex))
                    .registerWriteHandler(horizontalCellStyleStrategy)
//                    .registerWriteHandler(new SimpleColumnWidthStyleStrategy(30))
                    .registerWriteHandler(new AbstractColumnWidthStyleStrategy() {
                        @Override
                        protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<CellData> list, Cell cell, Head head, Integer integer, Boolean aBoolean) {
                            Sheet sheet = writeSheetHolder.getSheet();
                            int columnIndex = cell.getColumnIndex();
                            if(columnIndex == 5){
                                //  Column width 100
                                sheet.setColumnWidth(columnIndex, 10000);
                            }else {
                                //  Column width 50
                                sheet.setColumnWidth(columnIndex, 5000);
                            }
                            //  Row height 40
                            sheet.setDefaultRowHeight((short) 4000);
                        }
                    })
                    .doWrite(list);
            output.flush();
        } catch (IOException e) {
            log.error(e.getMessage(), e);
        }
    }


    private List<List<String>> getHeaders(String dynamicTitle) {
        List<List<String>> headers=new ArrayList<>();
        List<String> schoolHead=new ArrayList<>();
        schoolHead.add(dynamicTitle);
        schoolHead.add(" School ");
        List<String> nameHead=new ArrayList<>();
        nameHead.add(dynamicTitle);
        nameHead.add(" full name ");
        List<String> sexHead=new ArrayList<>();
        sexHead.add(dynamicTitle);
        sexHead.add(" Gender ");
        List<String> ageHead=new ArrayList<>();
        ageHead.add(dynamicTitle);
        ageHead.add(" Age ");
        List<String> cityHead=new ArrayList<>();
        cityHead.add(dynamicTitle);
        cityHead.add(" City ");
        List<String> remarksHead=new ArrayList<>();
        remarksHead.add(dynamicTitle);
        remarksHead.add(" remarks ");
        headers.add(schoolHead);
        headers.add(nameHead);
        headers.add(sexHead);
        headers.add(ageHead);
        headers.add(cityHead);
        headers.add(remarksHead);
        return headers;
    }

    // Data manufacturing 
    private List<StudentExportVo> getStudentExportVos() {
        List<StudentExportVo> list = new ArrayList<>();
        StudentExportVo v1 = new StudentExportVo();
        v1.setSchool(" Peking University, ");
        v1.setName(" Zhang San ");
        v1.setSex(" male ");
        v1.setAge("20");
        v1.setCity(" Beijing ");
        v1.setRemarks(" nothing ");
        list.add(v1);
        StudentExportVo v2 = new StudentExportVo();
        v2.setSchool(" Peking University, ");
        v2.setName(" Li Si ");
        v2.setSex(" male ");
        v2.setAge("22");
        v2.setCity(" Shanghai ");
        v2.setRemarks(" nothing ");
        list.add(v2);
        StudentExportVo v3 = new StudentExportVo();
        v3.setSchool(" Peking University, ");
        v3.setName(" Wang Wu ");
        v3.setSex(" Woman ");
        v3.setAge("22");
        v3.setCity(" Qingdao ");
        v3.setRemarks(" nothing ");
        list.add(v3);
        StudentExportVo v4 = new StudentExportVo();
        v4.setSchool(" Tsinghua University ");
        v4.setName(" Zhao Liu ");
        v4.setSex(" Woman ");
        v4.setAge("21");
        v4.setCity(" Chongqing ");
        v4.setRemarks(" nothing ");
        list.add(v4);
        StudentExportVo v5 = new StudentExportVo();
        v5.setSchool(" Wuhan University ");
        v5.setName(" Wang Qiang ");
        v5.setSex(" male ");
        v5.setAge("24");
        v5.setCity(" Changsha ");
        v5.setRemarks(" nothing ");
        list.add(v5);
        StudentExportVo v6 = new StudentExportVo();
        v6.setSchool(" Wuhan University ");
        v6.setName(" Zhao Yan ");
        v6.setSex(" Woman ");
        v6.setAge("21");
        v6.setCity(" Shenzhen ");
        v6.setRemarks(" nothing ");
        list.add(v6);
        StudentExportVo v7 = new StudentExportVo();
        v7.setSchool(" Xiamen University ");
        v7.setName(" six thousand ");
        v7.setSex(" Woman ");
        v7.setAge("21");
        v7.setCity(" Guangzhou ");
        v7.setRemarks(" nothing ");
        list.add(v7);
        return list;
    }

Merge cells with the same content processing class ：ExcelMergeHandler

import com.alibaba.excel.metadata.CellData;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.write.handler.CellWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteTableHolder;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.util.CellRangeAddress;

import java.util.List;

public class ExcelMergeHandler implements CellWriteHandler {
    private int[] mergeColumnIndex;
    private int mergeRowIndex;

    public ExcelMergeHandler() {
    }

    public ExcelMergeHandler(int mergeRowIndex, int[] mergeColumnIndex) {
        this.mergeRowIndex = mergeRowIndex;
        this.mergeColumnIndex = mergeColumnIndex;
    }

    @Override
    public void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row, Head head, Integer columnIndex, Integer relativeRowIndex, Boolean isHead) {

    }

    @Override
    public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {

    }

    @Override
    public void afterCellDataConverted(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, CellData cellData, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {

    }

    @Override
    public void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {

        // Current row 
        int curRowIndex = cell.getRowIndex();
        // Current column 
        int curColIndex = cell.getColumnIndex();

        if (curRowIndex > mergeRowIndex) {
            for (int i = 0; i < mergeColumnIndex.length; i++) {
                if (curColIndex == mergeColumnIndex[i]) {
                    mergeWithPrevRow(writeSheetHolder, cell, curRowIndex, curColIndex);
                    break;
                }
            }
        }
    }


    /**
     *  Merge the current cell up 
     *
     * @param writeSheetHolder
     * @param cell              Current cell 
     * @param curRowIndex       Current row 
     * @param curColIndex       Current column 
     */
    private void mergeWithPrevRow(WriteSheetHolder writeSheetHolder, Cell cell, int curRowIndex, int curColIndex) {
        Object curData = cell.getCellTypeEnum() == CellType.STRING ? cell.getStringCellValue() : cell.getNumericCellValue();
        Cell preCell = cell.getSheet().getRow(curRowIndex - 1).getCell(curColIndex);
        Object preData = preCell.getCellTypeEnum() == CellType.STRING ? preCell.getStringCellValue() : preCell.getNumericCellValue();
        //  Compare the current cell data with the previous cell data 
        Boolean dataBool = preData.equals(curData);
        // Notice here ： Because I decide whether to merge according to the project name , So get the data in the second column of each row and compare it with the data in the first column of the previous row , If equal, merge ,getCell The value of the inside , Is the subscript of the project name column 
        String s1 = cell.getRow().getCell(0).getStringCellValue();
        String s2 = cell.getSheet().getRow(curRowIndex - 1).getCell(0).getStringCellValue();
        /*BigDecimal d1 = new BigDecimal(cell.getRow().getCell(0).getNumericCellValue());
        BigDecimal d2 = new BigDecimal(cell.getSheet().getRow(curRowIndex - 1).getCell(0).getNumericCellValue());*/
        Boolean bool = s1.compareTo(s2) == 0 ? true:false;
        //  The original 
        // Boolean bool =  cell.getRow().getCell(1).getStringCellValue().equals(cell.getSheet().getRow(curRowIndex - 1).getCell(1).getStringCellValue());
        if (dataBool && bool) {
            Sheet sheet = writeSheetHolder.getSheet();
            List<CellRangeAddress> mergeRegions = sheet.getMergedRegions();
            boolean isMerged = false;
            for (int i = 0; i < mergeRegions.size() && !isMerged; i++) {
                CellRangeAddress cellRangeAddr = mergeRegions.get(i);
                //  If the previous cell has been merged , The original merging unit is removed first , Add the merge cell again 
                if (cellRangeAddr.isInRange(curRowIndex - 1, curColIndex)) {
                    sheet.removeMergedRegion(i);
                    cellRangeAddr.setLastRow(curRowIndex);
                    sheet.addMergedRegion(cellRangeAddr);
                    isMerged = true;
                }
            }
            //  If the previous cell is not merged , Add a new merging unit 
            if (!isMerged) {
                CellRangeAddress cellRangeAddress = new CellRangeAddress(curRowIndex - 1, curRowIndex, curColIndex, curColIndex);
                sheet.addMergedRegion(cellRangeAddress);
            }
        }
    }
}

summary ：

1、 When using custom to merge cells with the same content , Annotations in entity classes @ContentLoopMerge Need to get rid of it. , Otherwise it will be affected

2、 Such as content merging in this customized code 、 Set dynamic title 、 Content 、 And the width and font of each column can be set according to the custom policy , For specific usage, please refer to the code notes , Use as needed

3、 You can refer to the official website for more information  https://alibaba-easyexcel.github.io/index.html

Last ：
        I believe that the first two export methods are used by students very skillfully , The focus is on the third custom export method , There are many custom usage scenarios like this , I hope to encounter similar scenarios in the development , Just take the code and use it directly , Take fewer detours .