动态表头导出EasyExcel

在 Spring Boot 中结合 EasyExcel 实现动态表头导出（无实体类，表头和字段（前端传表名，字段值动态查询，返回List<Map<String,Object>>）由前端传递）可以通过以下步骤实现。以下是完整示例：

1. 前端请求数据结构

假设前端传递的 JSON 格式如下：

{"headers": [{"title": "姓名", "field": "name"},{"title": "年龄", "field": "age"},{"title": "城市", "field": "city"}],"data": [{"name": "张三", "age": 25, "city": "北京"},{"name": "李四", "age": 30, "city": "上海"}]
}

2. 后端 DTO 定义

定义接收参数的 DTO 类：

@Data
public class ExportRequest {private List<Header> headers;private List<Map<String, Object>> data;@Datapublic static class Header {private String title;  // 表头名称private String field;  // 数据字段名}
}

3. Controller 层接口

处理导出请求：

@RestController
public class ExportController {@Autowiredprivate ExportService exportService;@PostMapping("/export")public void exportExcel(@RequestBody ExportRequest request, HttpServletResponse response) {exportService.export(request, response);}
}

4. Service 层实现

核心导出逻辑：

@Service
public class ExportService {public void export(ExportRequest request, HttpServletResponse response) {try {// 设置响应头response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("UTF-8");String fileName = URLEncoder.encode("动态导出.xlsx", "UTF-8");response.setHeader("Content-Disposition", "attachment; filename=" + fileName);// 获取输出流OutputStream outputStream = response.getOutputStream();// 动态构建表头和数据WriteSheet writeSheet = EasyExcel.writerSheet("Sheet1").build();ExcelWriter excelWriter = EasyExcel.write(outputStream).build();// 动态添加表头WriteTable writeTable = new WriteTable();List<List<String>> head = buildHead(request.getHeaders());writeTable.setHead(head);// 动态填充数据List<List<Object>> data = buildData(request.getHeaders(), request.getData());excelWriter.write(data, writeSheet, writeTable);// 关闭流excelWriter.finish();outputStream.flush();} catch (IOException e) {throw new RuntimeException("导出失败", e);}}// 构建表头private List<List<String>> buildHead(List<ExportRequest.Header> headers) {List<List<String>> head = new ArrayList<>();for (ExportRequest.Header header : headers) {List<String> columnHead = Collections.singletonList(header.getTitle());head.add(columnHead);}return head;}// 构建数据行private List<List<Object>> buildData(List<ExportRequest.Header> headers, List<Map<String, Object>> dataList) {List<List<Object>> data = new ArrayList<>();for (Map<String, Object> rowData : dataList) {List<Object> row = new ArrayList<>();for (ExportRequest.Header header : headers) {row.add(rowData.get(header.getField()));}data.add(row);}return data;}
}

5. 关键点说明

动态表头
- 通过 buildHead() 方法将前端传递的 headers 转换为 EasyExcel 需要的 List<List<String>> 格式。
动态数据
- 通过 buildData() 方法，根据 headers 中定义的 field 字段顺序，从 data 中提取对应值，构建数据行。
流式导出
- 使用 ExcelWriter 直接操作输出流，避免内存溢出（适合大数据量）。

6. 测试与验证

使用 Postman 发送请求：

URL: POST http://localhost:8080/export

Body（JSON）：

{"headers": [{"title": "姓名", "field": "name"},{"title": "年龄", "field": "age"},{"title": "城市", "field": "city"}],"data": [{"name": "张三", "age": 25, "city": "北京"},{"name": "李四", "age": 30, "city": "上海"}]
}