需求

在一般需求中点击导出按钮可以把所有的分类导出到Excel文件中。

技术方案

使用EasyExcel实现Excel的导出操作。
https://github.com/alibaba/easyexcel
https://easyexcel.opensource.alibaba.com/docs/current/quickstart/write#%E7%A4%BA%E4%BE%8B%E4%BB%A3%E7%A0%81-1

web中的写并且失败的时候返回json

    /**
     * 文件下载并且失败的时候返回json（默认失败了会返回一个有部分数据的Excel）
     *
     * @since 2.1.1
     */
    @GetMapping("downloadFailedUsingJson")
    public void downloadFailedUsingJson(HttpServletResponse response) throws IOException {
        // 这里注意 有同学反应使用swagger 会导致各种问题，请直接用浏览器或者用postman
        try {
            response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
            response.setCharacterEncoding("utf-8");
            // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
            String fileName = URLEncoder.encode("测试", "UTF-8").replaceAll("\\+", "%20");
            response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
            // 这里需要设置不关闭流
            EasyExcel.write(response.getOutputStream(), DownloadData.class).autoCloseStream(Boolean.FALSE).sheet("模板")
                .doWrite(data());
        } catch (Exception e) {
            // 重置response
            response.reset();
            response.setContentType("application/json");
            response.setCharacterEncoding("utf-8");
            Map<String, String> map = MapUtils.newHashMap();
            map.put("status", "failure");
            map.put("message", "下载文件失败" + e.getMessage());
            response.getWriter().println(JSON.toJSONString(map));
        }
    }

接口设计

请求方式 请求地址 请求头
GET /content/category/export 需要token请求头
CategoryController

  @GetMapping("/export")
    public void export(HttpServletResponse response){

        try {
            //设置下载文件的请求头
            WebUtils.setDownLoadHeader("分类.xlsx",response);
            //获取需要导出的数据
            List<Category> categoryVOs = categoryService.list();

            List<ExcelCategoryVO> excelCategoryVOs = BeanCopyUtils.copyBeanList(categoryVOs, ExcelCategoryVO.class);
            //把数据写入到Excel中
            EasyExcel.write(response.getOutputStream(), ExcelCategoryVO.class).autoCloseStream(Boolean.FALSE).sheet("分类导出")
                    .doWrite(excelCategoryVOs);
        } catch (Exception e) {
            e.printStackTrace();
            //如果出现异常也要响应json
            ResponseResult result = ResponseResult.errorResult(AppHttpCodeEnum.SYSTEM_ERROR);
            WebUtils.renderString(response, JSON.toJSONString(result));
        }

WebUtils

public class WebUtils
{
    /**
     * 将字符串渲染到客户端
     * 
     * @param response 渲染对象
     * @param string 待渲染的字符串
     * @return null
     */
    public static void renderString(HttpServletResponse response, String string) {
        try
        {
            response.setStatus(200);
            response.setContentType("application/json");
            response.setCharacterEncoding("utf-8");
            response.getWriter().print(string);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }


    public static void setDownLoadHeader(String filename, HttpServletResponse
            response) throws UnsupportedEncodingException {
        response.setContentType("application/vnd.openxmlformatsofficedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        String fname= URLEncoder.encode(filename,"UTF-8").replaceAll("\\+",
                "%20");
        response.setHeader("Content-disposition","attachment; filename="+fname);
    }
}

ExcelCategoryVO

@Data
@NoArgsConstructor
@AllArgsConstructor
public class ExcelCategoryVO {
    @ExcelProperty("分类名")
    private String name;
    //描述
    @ExcelProperty("描述")
    private String description;

    //状态0:正常,1禁用
    @ExcelProperty("状态0:正常,1禁用")
    private String status;
}

CategoryVO

@Data
@NoArgsConstructor
@AllArgsConstructor
public class CategoryVO {

    private Long id;

    private String name;
    //描述
    private String description;

}

效果展示