现象

EasyExcel 支持导出 xlsx、xls、csv 三种文件格式。在导出过程中可能发生各种异常，当发生异常时应该提示错误信息而非导出一个错误的文件。

分析

• 首先，后端应该支持两种不同格式（content-type）内容的返回
• 其次，前端应该支持两种不同格式（content-type）内容的解析处理

解决（伪代码）

前端 POST 实现

const axios = require('axios');

axios({
	url: 'https://api.example.com/export',
	method: 'post',
	data: {
		param1: 'value1',
		param2: 'value2'
	},
	responseType: 'blob',
	headers: {
		'Authorization': 'Bearer YOUR_TOKEN'
	}
})
.then(response => {
	if (response.data && response.data.type == 'application/json') {
		const render = new FileReader();
		reader.onload = (e) => {
			let content = e.target.result;
			content = JSON.parse(content);
			this.$antMessage.info(content.msg);
		}
	} else {
		var blob = new Blob([response.data]);
		const url = window.URL.createObjectURL(blob);
		const link = document.createElement('a');
		link.style.display = 'none';
		link.href = url;
		link.setAttribute('download', name);
		document.body.appendChild(link);
		link.click();
		document.body.removeChild(link);
	}
})
.catch(error => {
  	console.error('Error:', error);
});

后端实现

if (errorCondition) {
	throw new BusinessException('errorCode', 'errorMsg');
}

response.setContentType(ExcelConst.MEDIA_TYPE_EXCEL);
response.setHeader(ExcelConst.CONTENT_DISPOSITION, String.format("%s:%s=%s.%s", ExcelConst.ATTACHMENT, ExcelConst.FILENAME, System.currentTimeMillis(), ExcelTypeEnum.XLSX.getValue()));

try (OutputStream os = response.getOutputStream(); ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
    ExcelWriter excelWriter = EasyExcel.write(baos)
            .charset(Charset.forName("GBK")) // 或者 UTF-8
            .autoCloseStream(true)
            .excludeColumnFieldNames(Lists.newArrayList())
            .excelType(ExcelTypeEnum.XLSX).build();

	WriteSheet writeSheet = EasyExcel.writerSheet(sheetNo, sheetName).head(clazz).build();
	excelWriter.write(sheetData, writeSheet);

    excelWriter.finish();

    os.write(baos.toByteArray());
} catch (Exception e) {
    log.error(String.format("Excel 导出失败！%s", ""), e);
}