写一个java 动态生成excel表头的代码

好的，我可以帮你生成动态的Excel表头。你可以使用Apache POI这个Java库来实现。以下是一个Java代码示例：

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.CellStyle;
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.usermodel.Workbook;
import org.apache.poi.ss.util.CellRangeAddress;

import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

public class ExcelGenerator {

    public static void main(String[] args) {
        List<String> headers = new ArrayList<>();
        headers.add("ID");
        headers.add("Name");
        headers.add("Email");
        headers.add("Phone");

        // Create a new workbook
        Workbook workbook = new HSSFWorkbook();

        // Create a new sheet
        Sheet sheet = workbook.createSheet("Sheet1");

        // Create a new row for the header
        Row headerRow = sheet.createRow(0);

        // Create a cell style for the header
        CellStyle headerCellStyle = workbook.createCellStyle();
        headerCellStyle.setAlignment(CellStyle.ALIGN_CENTER);

        // Set the column width for each column
        sheet.setColumnWidth(0, 10000);
        sheet.setColumnWidth(1, 10000);
        sheet.setColumnWidth(2, 15000);
        sheet.setColumnWidth(3, 10000);

        // Generate the header cells dynamically
        for (int i = 0; i < headers.size(); i++) {
            Row currentRow = headerRow;
            int currentColumn = i;

            // Merge cells for the header
            sheet.addMergedRegion(new CellRangeAddress(0, 1, currentColumn, currentColumn));

            // Create the header cell
            Row row = sheet.getRow(0);
            if (row == null) {
                row = sheet.createRow(0);
            }
            row.setHeight((short) 800);

            Cell headerCell = row.createCell(currentColumn);
            headerCell.setCellValue(headers.get(i));
            headerCell.setCellStyle(headerCellStyle);

            // Create the second row of the header
            Row secondRow = sheet.getRow(1);
            if (secondRow == null) {
                secondRow = sheet.createRow(1);
            }

            // Set the data type for the header cell
            headerCell.setCellType(CellType.STRING);

            // Autofit the column width to fit the header text
            sheet.autoSizeColumn(i);
        }

        try {
            // Save the workbook to an OutputStream
            OutputStream outputStream = new FileOutputStream("example.xlsx");
            workbook.write(outputStream);
            workbook.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

这段代码将生成一个包含动态表头的Excel文件，并使用Apache POI库进行操作。你可以根据需要修改列的数量和列标题，以生成任意数量列的动态表头。