导出数据为zip压缩文件，解压后为json文件

1. 前端只要将要导出的数据的ids传回后端就行了

比如

    handleExportApp(row) {
      const ids = row ? [row.id] : this.checkedRows.map(v => v.id); 
      //exportApp为后端导出接口
      exportApp(ids.join(","));
    },

2. 后端接口

    public void exportApp(String ids, HttpServletResponse response) {
        if (StringUtils.isBlank(ids)) {
            throw new BusinessException("参数不能为空");
        }
        List<String> idsList = Arrays.asList(ids.split(","));
        List<App> list = appService.findAppAllListByIds(idsList);
        //创建HttpServerResponse的输出流
        OutputStream out = null;
        try {
            out = response.getOutputStream();
            BufferedInputStream bis;
            File file = new File("应用数据包.zip");
            //通过ZipOutputStream定义要写入的对象
            ZipOutputStream zos = null;
            zos = new ZipOutputStream(new FileOutputStream(file));
            writeZos(list, zos);
            zos.close();
            //定义返回类型
            response.setContentType("text/html; charset=UTF-8");
            response.setContentType("application/octet-stream");
            response.setHeader("Content-Disposition", "attachment;filename=".concat(String.valueOf(URLEncoder.encode("应用数据包.zip", "UTF-8"))));
            bis = new BufferedInputStream(new FileInputStream(file));
            //定义byte，长度就是要转成zip文件的byte长度，避免浪费资源
            byte[] buffer = new byte[bis.available()];
            bis.read(buffer);
            out.flush();
            out.write(buffer);
            file.delete();
        } catch (IOException e) {
            logger.error("应用数据包流写入异常{}", e.getMessage());
            throw new BusinessException("系统异常");
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
     }
   
   
   
    public void writeZos(List<App> list, ZipOutputStream zos) {
        list.forEach(a -> {
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            try {
                byteArrayOutputStream.write(JSONUtil.toJsonStr(a).getBytes());
                zos.putNextEntry(new ZipEntry(a.getName() + ".json"));
                byte[] excelStream = byteArrayOutputStream.toByteArray();
                zos.write(excelStream);
                zos.closeEntry();
            } catch (IOException e) {
                logger.error("应用数据包流写入异常{}", e.getMessage());
                throw new BusinessException("系统异常");
            }
        });
    }
   

拓展

如果只是导出json文件，不需要压缩包的话
前端

    handleExportApp(row) {
      this.ids = row ? [row.id] : this.checkedRows.map(v => v.id);
      this.loading = true;
      this.exportData(this.ids);
    },

    exportData(ids) {
      if (ids.length > 0) {
        const currentId = ids.shift(); // 取出数组中的第一个id
        simulateClick(exportApp(currentId)); // 导出单个数据
        setTimeout(() => {
          this.exportData(ids); // 递归调用导出函数，继续下一个数据
        }, 10000); // 设置递归的间隔时间，以免处理过多数据造成性能问题
      }
    },

后端

        if (StringUtils.isBlank(ids)) {
            throw new BusinessException("参数不能为空");
        }
        List<String> idsList = Arrays.asList(ids.split(","));

        for (String id : idsList) {
            App app = appService.getById(id);

            // 忽略未找到的应用程序
            if (app == null) {
                continue;
            }
            ObjectMapper objectMapper = new ObjectMapper();
            try {
            	//把对象转成json字符串
                String jsonString = objectMapper.writeValueAsString(app);

                // 设置响应头部信息
                response.setContentType("application/json");
                response.setCharacterEncoding("UTF-8");
                response.setHeader("Content-Disposition", "attachment;filename=".concat(String.valueOf(URLEncoder.encode("应用_" + app.getName() + ".json", "UTF-8"))));

                // 获取输出流并写入JSON字符串
                PrintWriter writer = response.getWriter();
                writer.write(jsonString);
                writer.flush();
                writer.close();
            } catch (IOException e) {
                logger.error("导出应用数据异常：{}", e.getMessage());
                throw new BusinessException("系统异常");
            }
        }

但是这样有一个不好的地方，就是前端用户体验感不是很好，需要等待前端一个个文件导出。