java导出多sheet的excel

csv无法多sheet，JavaPOI导出excel有三种形式：HSSFworkbook,XSSFworkbook,SXSSFworkbook
区别如下：
https://blog.csdn.net/weixin_45631654/article/details/119457460?spm=1001.2014.3001.5502

本次示例是XSSFworkbook，
注意：单元格的限制是32767个字符，超出会报错导出失败。

依赖如下：

   <properties>
      <spring.version>4.3.19.RELEASE</spring.version>
        <poi.version>3.16</poi.version>
    </properties>
    <dependencies>
       <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>${poi.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>${poi.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml-schemas</artifactId>
            <version>${poi.version}</version>
        </dependency>
   </dependencies>

代码如下：

package csv;


import org.apache.poi.xssf.usermodel.*;

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

public class POITEST {
    public static void main(String[] args) {
        try {
            //excel导出的路径和名称
            OutputStream out = new FileOutputStream("/home/quyanhang/Downloads/test.xlsx");
            //生成两个sheet,不同的数据源和列标题
            List<List<Object>> data1 = new ArrayList<>();
            List<List<Object>> data2 = new ArrayList<>();
            String[] headers1 = {"编号", "年龄", "用户名"};
            String[] headers2 = {"编号", "用户名"};
            HashMap<String, String[]> header = new HashMap<>();
            header.put("表单-1", headers1);
            header.put("表单-2", headers2);
            //注意int等其他类型转换成String类型
            //表单-2的数据内容
            for (int i = 1; i < 5; i++) {
                List rowData = new ArrayList();
                rowData.add(String.valueOf(i));
                rowData.add(String.valueOf(i + 20));
                rowData.add("曲" + i + "号");
                data1.add(rowData);
            }
            //表单-1的数据内容
            for (int i = 1; i < 5; i++) {
                List rowData = new ArrayList();
                rowData.add(String.valueOf(i));
                rowData.add("曲" + i + "号");
                data2.add(rowData);
            }

            XSSFWorkbook workbook = new XSSFWorkbook();
            HashMap<String, List<List<Object>>> map = new HashMap<>();
            map.put("表单-1", data1);
            map.put("表单-2", data2);
            int a = 0;
            for (String key : map.keySet()) {
                System.out.println(key);
                System.out.println(a);
                exportExcel(workbook, a, key, header.get(key), map.get(key), out);
                a = a + 1;
            }
            workbook.write(out);
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    /**
     * @param workbook
     * @param sheetNum   sheet的位置，0表示第一个表格中的第一个sheet
     * @param sheetTitle sheet的名称
     * @param headers    标题
     * @param result     内容
     * @param out        输出流
     */
    public static void exportExcel(XSSFWorkbook workbook, int sheetNum,
                                   String sheetTitle, String[] headers, List<List<Object>> result,
                                   OutputStream out) throws Exception {
        // 生成一个表格
        XSSFSheet sheet = workbook.createSheet();
        workbook.setSheetName(sheetNum, sheetTitle);

        // 设置表格默认列宽度为20个字节
        sheet.setDefaultColumnWidth((short) 20);
        // 产生表格标题行
        XSSFRow row = sheet.createRow(0);
        for (int i = 0; i < headers.length; i++) {
            XSSFCell cell = row.createCell((short) i);
            XSSFRichTextString text = new XSSFRichTextString(headers[i]);
            cell.setCellValue(text.toString());
        }
        // 遍历集合数据，产生数据行
        if (result != null) {
            int index = 1;
            for (List<Object> m : result) {
                row = sheet.createRow(index);
                int cellIndex = 0;
                for (Object str : m) {
                    XSSFCell cell = row.createCell((short) cellIndex);
                    cell.setCellValue(str.toString());
                    cellIndex++;
                }
                index++;
            }
        }

    }

}