package com.xtl.utils;

import lombok.Data;

import java.util.LinkedList;
import java.util.List;

@Data
public class HeaderNode {
    private String title;
    private List<HeaderNode> children;

    public HeaderNode(String title) {
        this.title = title;
        this.children = new LinkedList<>();
    }

    public HeaderNode addChild(HeaderNode child) {
        children.add(child);
        return this;
    }
}

package com.xtl.utils;

import java.util.*;

public class HeaderBuilder {
    private final HeaderNode root;

    private HeaderBuilder(HeaderNode root) {
        this.root = root;
    }

    public static HeaderBuilder create(HeaderNode... headerNodes) {
        HeaderNode root = new HeaderNode("ROOT"); // 虛擬根節(jié)點(diǎn)
        for (HeaderNode node : headerNodes) {
            root.addChild(node);
        }
        return new HeaderBuilder(root);
    }

    /**
     * 生成多級表頭結(jié)構(gòu)
     *
     * @return 適用于EasyExcel的嵌套表頭結(jié)構(gòu)
     */
    public List<List<String>> build() {
        List<List<String>> result = new ArrayList<>();
        traverse(new LinkedList<>(), root, result);
        return result;
    }


    private void traverse(LinkedList<String> currentPath, HeaderNode node, List<List<String>> result) {
        if (node.getChildren() == null || node.getChildren().isEmpty()) {
            result.add(new ArrayList<>(currentPath));
            return;
        }
        for (HeaderNode child : node.getChildren()) {
            currentPath.add(child.getTitle());
            traverse(currentPath, child, result);
            currentPath.removeLast();
        }
    }
}

package com.xtl.utils;

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.write.metadata.WriteSheet;

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

public class Main {
    public static void main(String[] args) {
        // 構(gòu)建表頭結(jié)構(gòu)
        HeaderNode user = new HeaderNode("用戶")
               .addChild(new HeaderNode("姓名"))
               .addChild(new HeaderNode("年齡"))
               .addChild(new HeaderNode("性別"));
        HeaderNode address = new HeaderNode("地址")
               .addChild(new HeaderNode("省份"))
               .addChild(new HeaderNode("城市"));
        HeaderNode score = new HeaderNode("分?jǐn)?shù)");
        List<List<String>> header = HeaderBuilder.create(user, address, score).build();

        System.out.println(header);
        // 準(zhǔn)備數(shù)據(jù)
        List<List<String>> data = new ArrayList<>();
        data.add(Arrays.asList("張三", "25", "男", "浙江", "杭州", "20"));
        data.add(Arrays.asList("李四", "30", "女", "江蘇", "南京", "20"));
        ExcelWriter excelWriter = EasyExcel.write("demo.xlsx").build();
        WriteSheet sheet = EasyExcel.writerSheet()
               .head(header)
               .build();
        excelWriter.write(data, sheet);
        excelWriter.finish();
    }
}