普通导出数据

需求

需要将相同列数据合并

效果图：

代码：

package cn.silence.test;

import lombok.AllArgsConstructor;
import lombok.Data;

/**
 * 班级信息
 */
@Data
@AllArgsConstructor
public class ClassInfo {
    /**
     * 学院
     */
    private String academy;
    /**
     * 系
     */
    private String system;
    /**
     * 专业
     */
    private  String specialized;
    /**
     * 班级
     */
    private String className;
}

package cn.silence.test;

import cn.hutool.core.util.StrUtil;
import cn.hutool.poi.excel.BigExcelWriter;
import cn.hutool.poi.excel.ExcelUtil;
import org.jetbrains.annotations.NotNull;

import java.io.File;
import java.util.TreeSet;
import java.util.concurrent.atomic.AtomicInteger;

public class Excel {

    public static void main(String[] args) {
        //读取数据 并根据需求排序
        TreeSet<ClassInfo> set = getClassInfos();

        //excel写出位置
        File file = new File("C:\\Users\\Administrator\\Desktop\\777.xlsx");
        BigExcelWriter writer = ExcelUtil.getBigWriter(file);

        //定义需要合并的列===========================================
        ClassInfo first = set.first();
        //学院
        String academy = first.getAcademy();
        AtomicInteger academyIndex = new AtomicInteger(1);
        //系
        String system = first.getSystem();
        AtomicInteger systemIndex = new AtomicInteger(1);
        //专业
        String specialized = first.getSpecialized();
        AtomicInteger specializedIndex = new AtomicInteger(1);

        //根据条件合并，出现不同的字段名称，则将该行号与之前的行号之间的行合并。
        AtomicInteger count = new AtomicInteger(1);
        for (ClassInfo classInfo : set) {
            academy = marge(academy, classInfo.getAcademy(), academyIndex, count, writer, 0);
            system = marge(system, classInfo.getSystem(), systemIndex, count, writer, 1);
            specialized = marge(specialized, classInfo.getSpecialized(), specializedIndex, count, writer, 2);
            count.incrementAndGet();
        }

        //结尾合并
        count.decrementAndGet();
        endMarge(academyIndex.get(), count.get(), 0, academy, writer);
        endMarge(systemIndex.get(), count.get(), 0, system, writer);
        endMarge(specializedIndex.get(), count.get(), 0, specialized, writer);

        //write
        writer.setColumnWidth(-1, 40);
        writer.write(set);
        writer.flush();
        writer.close();
    }

    /**
     * 尾行合并
     */
    private static void endMarge(int startIndex, int endIndex, int row, String title, BigExcelWriter writer) {
        if ((startIndex == endIndex) || (startIndex > endIndex)) {
            return;
        }
        writer.merge(startIndex, endIndex, row, row, title, true);
    }

    /**
     * 判断是否需要合并
     */
    private static String marge(String oldValue, String newValue, AtomicInteger index, AtomicInteger count, BigExcelWriter writer, int row) {
        if (StrUtil.equals(oldValue, newValue)) {
            return oldValue;
        }
        int endIndex = count.get() - 1;
        if (index.get() == endIndex) {
            index.incrementAndGet();
            return newValue;
        }
        writer.merge(index.get(), endIndex, row, row, oldValue, true);
        index.set(endIndex);
        index.incrementAndGet();
        return newValue;
    }

    /**
     * 生成测试数据
     */
    @NotNull
    private static TreeSet<ClassInfo> getClassInfos() {
        TreeSet<ClassInfo> set = new TreeSet<>((o1, o2) -> {
            int compareAcademy = o1.getAcademy().compareTo(o2.getAcademy());
            if (compareAcademy != 0) return compareAcademy;

            int compareSystem = o1.getSystem().compareTo(o2.getSystem());
            if (compareSystem != 0) return compareSystem;

            int compareSpecialized = o1.getSpecialized().compareTo(o2.getSpecialized());
            if (compareSpecialized != 0) return compareSpecialized;

            return o1.getClassName().compareTo(o2.getClassName());
        });
        set.add(new ClassInfo("绘画艺术学院", "油画系", "油画", "1班"));
        set.add(new ClassInfo("绘画艺术学院", "油画系", "油画", "2班"));
        set.add(new ClassInfo("工业设计学院", "直属学院", "产品设计", "20产品甲"));
        set.add(new ClassInfo("绘画艺术学院", "油画系", "油画", "3班"));
        set.add(new ClassInfo("工业设计学院", "直属学院", "产品设计", "21产品乙"));
        set.add(new ClassInfo("绘画艺术学院", "壁画系", "壁画", "4班"));
        set.add(new ClassInfo("绘画艺术学院", "版画系", "版画", "4班"));
        set.add(new ClassInfo("绘画艺术学院", "壁画系", "壁画", "4班"));
        set.add(new ClassInfo("绘画艺术学院", "-", "美术学（硕士）", "-"));
        set.add(new ClassInfo("绘画艺术学院", "版画系", "版画", "4班"));
        set.add(new ClassInfo("绘画艺术学院", "-", "美术（硕士）", "-"));
        set.add(new ClassInfo("工业设计学院", "直属学院", "产品设计", "20产品丁"));
        set.add(new ClassInfo("绘画艺术学院", "油画系", "油画", "4班"));
        set.add(new ClassInfo("时尚设计学院", "服装设计系", "服装与服饰设计（服装设计）", "21服装乙"));
        set.add(new ClassInfo("时尚设计学院", "服装设计系", "服装与服饰设计（服装设计）", "20服装甲"));
        set.add(new ClassInfo("时尚设计学院", "服装设计系", "服装与服饰设计（服装设计）", "22时尚设计4班"));
        set.add(new ClassInfo("时尚设计学院", "服装设计系", "服装与服饰设计（染织设计）", "21染织"));
        set.add(new ClassInfo("时尚设计学院", "服装设计系", "服装与服饰设计（染织设计）", "20染织"));
        return set;
    }
}

       <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.8.15</version>
        </dependency>