org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class ReturnObj] with preset Content-Type 'application/octet-stream'

參考：https://blog.csdn.net/qq_44137046/article/details/116092565

本次的接口設(shè)計為導(dǎo)入解析接口，如果導(dǎo)入信息不符合，返回一個下載文件（application/octet-stream），符合則返回貨物集合信息（application/json）。

參考上面的鏈接內(nèi)容，確實是return null 就能解決問題。

原代碼將return null寫在service層，到controller層會仍然return ReturnObj，仍然會報錯，所以將代碼搬到controller層不會報錯：

@ApiOperation(value = "貨物信息批量導(dǎo)入")

@PostMapping(value = "/readCargosExcel")

public ReturnObj<List<TCargoVO>> readExcel(@RequestParam("file") MultipartFile file, HttpServletRequest request, HttpServletResponse response) throws IOException

{

return ReturnObj.success(tCargoService.readCargosExcel(file,request,response));

}

修改后：

@ApiOperation(value = "貨物信息批量導(dǎo)入")

@PostMapping(value = "/readCargosExcel")

public ReturnObj<List<TCargoVO>> readExcel(@RequestParam("file") MultipartFile file, HttpServletRequest request,HttpServletResponse response) throws IOException, MyException {

????ExcelImport<TCargoVO> excelImport = ExcelImport.create(file, TCargoVO::new);

????List<TCargoVO> list = excelImport.readAll();

????if (false) {

????????excelImport.response(response);

????????return null;

????}

????return ReturnObj.success(list);

}