easypoi可以通过注解的方式快速导出实体Excel。

导入easypoi依赖：

    compile group: 'cn.afterturn', name: 'easypoi-base', version: '4.2.0'
    compile group: 'cn.afterturn', name: 'easypoi-annotation', version: '4.2.0'
    compile group: 'cn.afterturn', name: 'easypoi-web', version: '4.2.0'

导入工具类

import cn.afterturn.easypoi.excel.ExcelExportUtil;
import cn.afterturn.easypoi.excel.entity.ExportParams;
import cn.afterturn.easypoi.excel.entity.enmus.ExcelType;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.stereotype.Component;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.Map;

/**
 * @Classname ExcelUtil
 * @Description Excel工具类
 */
@Component
public class ExcelUtil {

  /**
   * 导出excel
   *
   * @param list           泛型数据
   * @param title          标题
   * @param sheetName      sheet的名称
   * @param pojoClass      需要导出的对象
   * @param fileName       文件名称
   * @param isCreateHeader 是否创建表头
   * @throws IOException void
   */
  public void exportExcel(List<?> list, Class<?> pojoClass, String title, String sheetName, String fileName,
                          boolean isCreateHeader, HttpServletResponse response) throws IOException {
    final ExportParams exportParams = new ExportParams(title, sheetName, ExcelType.XSSF);
    exportParams.setCreateHeadRows(isCreateHeader);
    baseExport(list, pojoClass, fileName, exportParams, response);
  }

  /**
   * 最基础的对象导出
   *
   * @param list         数据列表
   * @param pojoClass    导出对象
   * @param fileName     文件名称
   * @param exportParams 导出文件属性
   * @throws IOException void
   */
  private void baseExport(List<?> list, Class<?> pojoClass, String fileName, ExportParams exportParams, HttpServletResponse response)
          throws IOException {
    final Workbook workbook = ExcelExportUtil.exportExcel(exportParams, pojoClass, list);
    downLoadExcel(fileName, workbook, response);
  }

  /**
   * 最基础的多sheet导出
   *
   * @param list     多个不同数据对象的列表
   * @param fileName 文件名称
   * @throws IOException void
   */
  private void baseExport(List<Map<String, Object>> list, String fileName, HttpServletResponse response) throws IOException {
    final Workbook workbook = ExcelExportUtil.exportExcel(list, ExcelType.HSSF);
    downLoadExcel(fileName, workbook, response);
  }


  /**
   * 文件下载
   *
   * @param fileName 文件名称
   * @param workbook exce对象
   * @throws IOException void
   */
  private void downLoadExcel(String fileName, Workbook workbook, HttpServletResponse response) throws IOException {
    ServletOutputStream output = null;
    try {
      final String downloadName = URLEncoder.encode(fileName + "." + "xlsx", StandardCharsets.UTF_8);
      response.setCharacterEncoding("UTF-8");
      response.setHeader("content-Type", "application/vnd.ms-excel");
      response.setHeader("Content-Disposition", "attachment;filename=" + downloadName);
      output = response.getOutputStream();
      workbook.write(output);
    } catch (final Exception e) {
      throw new IOException(e.getMessage());
    } finally {
      if (output != null) {
        output.flush();
        output.close();
      }
    }
  }


}

在需要导出的实体上注解@Excel(name = "表头名"),如果需要指定长度可以指定width

@Excel(name = "姓名")
private String name;

使用

  @Autowired
  ExcelUtil excelUtil;

  @GetMapping("/exportExcel")
  public void exportExcel(HttpServletResponse response) {
    
    List<User> all;

    String name = "用户列表";
    try {
      excelUtil.exportExcel(all, User.class, name, name, name, true, response);
    } catch (IOException e) {
      e.printStackTrace();
    } 
  }