easyexcel内容追加与单元格合并

这里的需求是，如果表格不存在，则新建表格，并填入数据，如果表格存在，那么就追加内容，并且支持单元格合并。

内容追加，需要分两种方式插入，第一种就是没有表格，需要生成表头，并且插入内容，第二种就是已经有了表格，这个表格作为模板并，不用设置表头，直接追加内容，这里需要生成一个新的表格，如果有必要，最后还要删除老的表格。

关于单元格合并，网上有这样的示例，使用easyexcel来实现，我们就是需要定义一个CellWriteHandler的接口实现，在实现类中，覆盖afterCellDispose()方法，本例中就是CustomCellWriteHandler类。

这里为了验证我们的结果，我们利用springboot构建两个不同的请求，一个是创建excel，一个是追加excel。

主要代码如下：

依赖文件：

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
	<groupId>org.projectlombok</groupId>
	<artifactId>lombok</artifactId>
</dependency>
<dependency>
	<groupId>com.alibaba</groupId>
	<artifactId>easyexcel-core</artifactId>
	<version>3.2.1</version>
</dependency>

控制器类：

import com.example.service.ExcelService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/excel")
public class ExcelController {

    @Autowired
    private ExcelService excelService;

    @GetMapping("/create")
    public ResponseEntity create() {
        return ResponseEntity.ok(excelService.create());
    }

    @GetMapping("/append")
    public ResponseEntity append() {
        return ResponseEntity.ok(excelService.append());
    }
}

服务类：

package com.example.service;

import com.alibaba.excel.EasyExcel;
import com.example.config.CustomCellWriteHandler;
import com.example.dao.ExcelDao;
import com.example.model.ExcelData;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.io.File;

@Service
public class ExcelService {

    @Autowired
    private ExcelDao excelDao;

    private String fileName = "e:\\test\\student.xlsx";

    private String tempName = "e:\\test\\temp.xlsx";

    private int mergeRowIndex = 0;

    private int[] mergeColumnIndexes = {0, 1, 2};

    public boolean create() {
        File out = new File(fileName);
        EasyExcel.write(out, ExcelData.class)
                .sheet("student")
                .registerWriteHandler(new CustomCellWriteHandler(mergeRowIndex,mergeColumnIndexes))
                .doWrite(excelDao.createData());
        return true;
    }

    public boolean append() {
        File out = new File(fileName);
        File temp = new File(tempName);
        if (out.exists()) {
            // 采用模板方式写入
            EasyExcel.write(out).needHead(false)
                    .withTemplate(out)
                    .file(temp)
                    .sheet("student")
                    .registerWriteHandler(new CustomCellWriteHandler(mergeRowIndex,mergeColumnIndexes))
                    .doWrite(excelDao.appendData());
            // out.delete();
            // temp.renameTo(out);
        }
        return true;
    }


}

数据接口模拟类：

package com.example.dao;

import com.example.model.ExcelData;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

@Component
public class ExcelDao {
    public List<ExcelData> createData() {
        List<ExcelData> list = new ArrayList<>();
        list.add(new ExcelData("罗芳",18, "female","语文",100));
        list.add(new ExcelData("罗芳",18, "female","数学",99));
        list.add(new ExcelData("王芳",17, "female","语文",80));
        list.add(new ExcelData("王芳",17, "female","数学",60));
        return list;
    }

    public List<ExcelData> appendData() {
        List<ExcelData> list = new ArrayList<>();
        list.add(new ExcelData("张雪琴",18, "female","语文",88));
        list.add(new ExcelData("张雪琴",18, "female","数学",75));
        list.add(new ExcelData("王勇",18, "male","语文",80));
        list.add(new ExcelData("王勇",18, "male","数学",92));
        return list;
    }
}

表格实体类：

package com.example.model;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class ExcelData {
    @ExcelProperty("学生姓名")
    private String name;

    @ExcelProperty("年龄")
    private int age;

    @ExcelProperty("性别")
    private String gender;

    @ExcelProperty({"课程", "课程名称"})
    private String courseName;

    @ExcelProperty({"课程", "分数"})
    private double score;
}

表格单元格合并策略类：

package com.example.config;

import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.metadata.data.WriteCellData;
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 CustomCellWriteHandler implements CellWriteHandler {

    private int mergeRowIndex;
    private int[] mergeColumnIndexes;

    public CustomCellWriteHandler(int mergeRowIndex, int[] mergeColumnIndexes) {
        this.mergeRowIndex = mergeRowIndex;
        this.mergeColumnIndexes = mergeColumnIndexes;
    }

    @Override
    public void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, List<WriteCellData<?>> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {
        int curRowIndex = cell.getRowIndex();
        int curColIndex = cell.getColumnIndex();
        if (curRowIndex > mergeRowIndex) {
            for (int i = 0; i < mergeColumnIndexes.length; i++) {
                if (curColIndex == mergeColumnIndexes[i]) {
                    mergeWithPrevRow(writeSheetHolder, cell, curRowIndex, curColIndex);
                    break;
                }
            }
        }
    }

    private void mergeWithPrevRow(WriteSheetHolder writeSheetHolder, Cell cell, int curRowIndex, int curColIndex) {
        Object curData = cell.getCellType() == CellType.STRING ? cell.getStringCellValue() : cell.getNumericCellValue();
        Row prevRow = cell.getSheet().getRow(curRowIndex - 1);
        if (prevRow != null) {
            Cell prevCell = prevRow.getCell(curColIndex);
            Object prevData = prevCell.getCellType() == CellType.STRING ? prevCell.getStringCellValue() : prevCell.getNumericCellValue();
            boolean isDataSame = curData.equals(prevData);
            if (isDataSame) {
                Sheet sheet = writeSheetHolder.getSheet();
                List<CellRangeAddress> mergeRegions = sheet.getMergedRegions();
                boolean isMerged = false;
                for (int i = 0; i < mergeRegions.size(); i++) {
                    CellRangeAddress cellRangeAddress = mergeRegions.get(i);
                    if (cellRangeAddress.isInRange(curRowIndex - 1, curColIndex)) {
                        sheet.removeMergedRegion(i);
                        cellRangeAddress.setLastRow(curRowIndex);
                        sheet.addMergedRegionUnsafe(cellRangeAddress);
                        isMerged = true;
                    }
                }
                if (!isMerged) {
                    CellRangeAddress cellRangeAddress = new CellRangeAddress(curRowIndex - 1, curRowIndex, curColIndex, curColIndex);
                    sheet.addMergedRegion(cellRangeAddress);
                }
            }
        }
    }


}

运行示例，分别访问 http://localhost:8080/excel/create 和 http://localhost:8080/excel/append 。

最后会生成两个文件，分别是e:\test\student.xlsx e:\test\temp.xlsx，内容如下所示：

内容是符合预期的，第一个只有两个学生信息，第二个表格因为是追加的，所以有四个学生信息。但是单元格合并，我们指定的是0，1，2三列，也就是姓名，年龄，性别需要合并，实际中他们确实合并了，但是似乎合并的超出了范围。我们希望合并的是同样学生的年龄和性别，而不是所有数值一样的年龄、性别。

解决办法就是在合并策略里面增加一个判断，如果合并行的列值（当前属性列age,gender）相同，而且第一列值（唯一属性name）也相同那么合并，而不是列的内容相同就合并。

变更过的合并策略主体逻辑：

private void mergeWithPrevRow(WriteSheetHolder writeSheetHolder, Cell cell, int curRowIndex, int curColIndex) {
	Object curData = cell.getCellType() == CellType.STRING ? cell.getStringCellValue() : cell.getNumericCellValue();
	Row prevRow = cell.getSheet().getRow(curRowIndex - 1);
	Row curRow = cell.getSheet().getRow(curRowIndex);
	if (prevRow == null) {
		prevRow = writeSheetHolder.getCachedSheet().getRow(curRowIndex - 1);
	}
	Cell prevFirstColCell = prevRow.getCell(0);
	Cell curFirstColCell = curRow.getCell(0);
	Object prevFirstColData = prevFirstColCell.getCellType() == CellType.STRING ? prevFirstColCell.getStringCellValue() : prevFirstColCell.getNumericCellValue();
	Object curFirstColData = curFirstColCell.getCellType() == CellType.STRING ? curFirstColCell.getStringCellValue() : curFirstColCell.getNumericCellValue();
	Cell prevCell = prevRow.getCell(curColIndex);
	Object prevData = prevCell.getCellType() == CellType.STRING ? prevCell.getStringCellValue() : prevCell.getNumericCellValue();
	boolean isDataSame = curData.equals(prevData) && curFirstColData.equals(prevFirstColData);
	if (isDataSame) {
		Sheet sheet = writeSheetHolder.getSheet();
		List<CellRangeAddress> mergeRegions = sheet.getMergedRegions();
		boolean isMerged = false;
		for (int i = 0; i < mergeRegions.size(); i++) {
			CellRangeAddress cellRangeAddress = mergeRegions.get(i);
			if (cellRangeAddress.isInRange(curRowIndex - 1, curColIndex)) {
				sheet.removeMergedRegion(i);
				cellRangeAddress.setLastRow(curRowIndex);
				sheet.addMergedRegionUnsafe(cellRangeAddress);
				isMerged = true;
			}
		}
		if (!isMerged) {
			CellRangeAddress cellRangeAddress = new CellRangeAddress(curRowIndex - 1, curRowIndex, curColIndex, curColIndex);
			sheet.addMergedRegion(cellRangeAddress);
		}
	}

}

生成的表格：

单元格合并范围超出问题似乎解决了，完美。

有的代码里面，在获取上一行记录某列的时候，代码是这样的：

Cell prevCell = cell.getSheet().getRow(curRowIndex - 1).getCell(curColIndex);

在实际中，这里可能会报空指针异常，其实数据在缓存里面，我们需要这样来获取：

Row prevRow = cell.getSheet().getRow(curRowIndex - 1);
if (prevRow == null) {
	prevRow = writeSheetHolder.getCachedSheet().getRow(curRowIndex - 1);
}

或者，在后面的逻辑里面加上判断 if (prevRow != null) 也是可以的。

easyexcel内容追加与单元格合并

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