Record the file upload and download of spring webplus.

There is no HTTP servlet request and HTTP servlet response based on servlet container before using webplus. Instead, there are org.springframework.http.server.reactive.ServerHttpRequest and org.springframework.http.server.reactive.ServerHttpResponse.

Application scenario:

1. File upload: the front end uploads the file, the back end parses the file content and saves it to the database;

2. File export: query data and export to file

File upload

@RequestMapping(value = "/console/routes/import", method = RequestMethod.POST,consumes = MediaType.MULTIPART_FORM_DATA_VALUE )
@ResponseBody
public Map<String,Object> importRouteConfig(@RequestPart(value="file") FilePart file)throws Exception {
	return routeConfigService.importRouteConfig(file);
}

Before and after reading the contents of the file, the logic is omitted:

@Override
public Map<String, Object> importRouteConfig(FilePart file) {
	Map<String, Object> objMap = new HashMap<String, Object>(GatewayNumberConstant.TWO);
	try{
		......
		// Read file contents
		String strFileInfo = ImportExportUtil.readJsonFile(file);
		......
		objMap.put("state", Boolean.valueOf(true));
	} catch (Exception e) {
		LOG.error("Import failed: unexpected exception.", e);
		objMap.put("message", "Unexpected exception, please contact the maintenance personnel for handling.");
		objMap.put("state", Boolean.valueOf(false));
	}
	return objMap;
}

Read file contents:

public static String readJsonFile(FilePart file) throws IOException {
	String strFileInfo = null;
	if(validateJsonFile(file)) {
		AtomicReference<String> bodyRef = new AtomicReference<>();
		file.content().subscribe(buffer->{
			CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer());
			DataBufferUtils.release(buffer);
			bodyRef.set(charBuffer.toString());
		});
		//Get request body
		strFileInfo = bodyRef.get();
		if(null==strFileInfo){
			LOG.error("Import failed: file is empty");
			throw new RuntimeException("Import failed: file is empty");
		}else if(strFileInfo.length()>MAX_DATA_SIZE){
			LOG.error("Import failed: file size cannot exceed 4 M");
			throw new RuntimeException("Import failed: file size cannot exceed 4 M");
		}
	}
	return strFileInfo;
}

Here strFileInfo is to get the file content information.

File export

@RequestMapping(value = "/console/routes/export", method = RequestMethod.GET)
@ResponseBody
public Mono<Void> exportRouteConfig(@RequestParam("ids") String[] ids, ServerHttpResponse response) {
	return routeConfigService.exportRouteConfig(ids, response);
}

Export tool class

/**
	* export file
	* 
	* @param fileName Filename, for example: GatewayRouteConfig
	* @param lstConfig Pass in the list to write to
	* @param response response
	*/
public static Mono<Void> exportJsonFile(String fileName, List lstConfig, ServerHttpResponse response) {
	if(null == lstConfig || lstConfig.isEmpty()) {
		LOG.error("The content of the export file is empty.");
		throw new RuntimeException("The content of the export file is empty.");
	}

	// Definition file name for example: GatewayRouteConfig-2019-01-07.json
	String strFileName = fileName + "-" + timestampConvertString(
			new Timestamp(System.currentTimeMillis()), "yyyy-MM-dd") + ".json";
	try {
		response.getHeaders().setContentType(MediaType.APPLICATION_JSON_UTF8);
		response.getHeaders().add("Content-Disposition", "attachment;filename=" 
					+ new String(strFileName.getBytes(DEFAULT_CHARSET_UTF_8), StandardCharsets.ISO_8859_1));

		Gson objGson = new Gson();
		String strRouteConfig = objGson.toJson(lstConfig);
		Flux<DataBuffer> flux = export(strRouteConfig);
		return response.writeWith(flux);

	} catch (UnsupportedEncodingException e) {
		LOG.error("Failed to export file:", e);
	} catch (Exception e) {
		LOG.error("Failed to export file:", e);
	} 
	return null;
}

It should be noted that the coding format of the exported file and the imported file should be consistent, otherwise, the Chinese code will be garbled.