Map<String, List<PortReportResultVo>> relayLinkAndPortMap = new HashMap<>(); 遍历这个map，value为要导出的数据，都在一个sheet页中分分成多块内容，每块内容的表头可以自定义为2行，用easyExcel实现详细代码，包括导包

请参考以下代码：

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.write.builder.ExcelWriterBuilder;
import com.alibaba.excel.write.metadata.WriteSheet;

import java.io.IOException;
import java.util.List;
import java.util.Map;

public class ExcelExporter {
    public static void export(Map<String, List<PortReportResultVo>> relayLinkAndPortMap) throws IOException {
        ExcelWriterBuilder writerBuilder = EasyExcel.write("output.xlsx");

        for (Map.Entry<String, List<PortReportResultVo>> entry : relayLinkAndPortMap.entrySet()) {
            String sheetName = entry.getKey();
            List<PortReportResultVo> data = entry.getValue();
            WriteSheet sheet = EasyExcel.writerSheet(sheetName).build();

            // 写入表头
            sheet.setHead(createHeader());

            // 写入数据
            writerBuilder.sheet(sheetName)
                    .head(createHeader())
                    .registerWriteHandler(new CustomizedCellStyleStrategy()) // 自定义单元格样式
                    .doWrite(data);
        }

        writerBuilder.build().finish();
    }

    private static List<List<String>> createHeader() {
        List<List<String>> header = new ArrayList<>();
        header.add(Arrays.asList("列1", "列2", "列3"));
        header.add(Arrays.asList("列1备注", "列2备注", "列3备注"));
        return header;
    }
}

其中，`PortReportResultVo` 为要导出的数据类型，`CustomizedCellStyleStrategy` 是自定义的单元格样式策略，可以根据需要进行修改。

需要导入的包有：

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.write.builder.ExcelWriterBuilder;
import com.alibaba.excel.write.metadata.WriteSheet;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.ArrayList;
import java.util.Arrays;