使用Spring进行文件的上传和下载

本文主要介绍在Spring框架下面调用微服务的dubbo rpc接口进行文件的上传和下载，以及记录在实现过程中遇到的一些容易出错的地方。

Spring上传文件接口设计

contoller层的代码实现如下所示：

    @PostMapping("/submitEvidence")public BaseResponse<?> submitEvidence(@RequestParam("id") Long id, @RequestParam("label") String label,@RequestParam(value = "file") MultipartFile file) {uploadEvidence(id, label, file);return BaseResponse.success().errorMsg("操作成功").build();}}

使用postman请求上传文件接口，具体参数如下图所示：
Service层代码实现如下所示：

public void uploadEvidence(Long takeDownId, String label, MultipartFile multipartFile) {if(Objects.isNull(multipartFile)) {throw new RunTimeException("上传的文件不能为空");}String fileName = multipartFile.getOriginalFilename();InputStream file = null;try {file = multipartFile.getInputStream();} catch (IOException e) {}byte[] fileBytes = new byte[20 * 1024 * 1024];InputStream inputStream = null;ByteArrayOutputStream outputStream = null;try {outputStream =  new ByteArrayOutputStream();inputStream = multipartFile.getInputStream();try {byte[] buffer = new byte[1024];int read = inputStream.read(buffer);while (read != -1) {outputStream.write(buffer, 0, read);read = inputStream.read(buffer);}} catch (Exception e) {log.error("处理返回值失败" + e.getMessage());throw new RunTimeException("上传文件失败");} finally {try {inputStream.close();} catch (IOException e) {e.printStackTrace();}}outputStream.flush();fileBytes = outputStream.toByteArray();} catch (IOException e) {}finally {if(outputStream != null) {try {outputStream.close();} catch (IOException e1) {e1.printStackTrace();throw new RuntimeException("上传文件失败");}}}UploadEvidenceNetCraftReq req = UploadEvidenceNetCraftReq.builder().takeDownId(takeDownId.intValue()).label(label).fileName(fileName).fileBytes(fileBytes).build();// outVendor是一个dubbo框架下的rpc服务，用于上传文件BaseResponse baseResponse = outerVendorsService.uploadEvidence(req);...}

dubbo接口设计

上传文件流的RPC的接口设计

我们构建的RPC接口采用的是dubbo框架，最初始的接口设计，将HttpServletResponse作为接口的参数类型传参，结果报错
io.netty.handler.codec.EncoderException: java.lang.IllegalStateException: Serialized class

Dubbo报错：io.netty.handler.codec.EncoderException: java.lang.IllegalStateException: Serialized class

HttpServletResponse不能被dubbo作为接口参数序列化，于是转而求其次，将可序列化的类型byte[]作为传输流的参数
outerVendorsService服务提供的上传文件的rpc接口：uploadEvidence接口，具体代码设计如下所示：

BaseResponse<UploadEvidenceRsp> uploadEvidence(UploadEvidenceReq req);
@Data
@Builder
@Jacksonized
public class UploadEvidenceReq implements Serializable {private Integer takeDownId;//使用可序列化的byte数组作为入参private byte[] fileBytes;private String fileName;private String label;
}@Data
@Setter
@Getter
public class UploadEvidenceRsp implements Serializable {private Integer file_id;@JsonProperty("error_code")private String errorCode;@JsonProperty("error_message")private String errorMessage;
}

Spring文件下载接口设计

文件下载的相关接口有两种实现：一种是将HttpServletResponse作为controller层的传参引入，将流写入到HttpServletResponse中，然后返回前端，但是在使用过程中，直接在HttpServletResponse的示例中setHeader失败，于是转而选择构ResponseEntity的方式来进行http返回值的构造，具体实现如下所示：

@GetMapping("/searchForEvidence")
public ResponseEntity searchForEvidence(@RequestParam String id) {return searchForEvidence(id);
}

使用postman请求下载文件接口，具体参数如下图所示：

Service层代码实现如下所示：

public ResponseEntity fetchEvidence(Long takeDownId){FetchEvidenceNetCraftReq req = FetchEvidenceNetCraftReq.builder().takeDownId(takeDownId.intValue()).build();BaseResponse<QueryEvidenceRsp> rsp = outerVendorsService.fetchEvidence(req);if(Objects.isNull(rsp)) {throw new RunTimeException("拉取文件失败");}byte[] outPutBytes = null;if(Objects.nonNull(rsp) && rsp.isSuccess() == true) {QueryEvidenceRsp evidenceRsp = rsp.getResult();if(Objects.nonNull(evidenceRsp.getErrorCode())){String message = "errorCode:" + evidenceRsp.getErrorCode() + ",errorMessage:" + evidenceRsp.getErrorMessage();throw new RunTimeException(message);}outPutBytes = evidenceRsp.getFileBytes();String fileName = evidenceRsp.getFileName();HttpHeaders responseHeaders = new HttpHeaders();responseHeaders.setContentType(MediaType.valueOf(MediaType.APPLICATION_OCTET_STREAM_VALUE));// 设置文件格式responseHeaders.setContentLength(outPutBytes.length);responseHeaders.set("Content-Disposition", "attachment;filename=" + fileName);// 设置文件名return new ResponseEntity<>(outPutBytes, responseHeaders, HttpStatus.OK);}throw new RunTimeException("拉取文件失败");
}public class QueryEvidenceRsp implements Serializable {byte[] fileBytes;String fileName;String errorCode;String errorMessage;
}

dubbo接口设计

下载文件流的RPC的接口设计

参照之前的上传文件的设计，服务提供的下载文件的rpc接口设计：

@Data
@Setter
@Getter
public class QueryEvidenceRsp implements Serializable {byte[] fileBytes;String fileName;String errorCode;String errorMessage;
}@Data
@Builder
@Jacksonized
public class FetchEvidenceNetCraftReq implements Serializable {private Integer takeDownId;
}@Overridepublic BaseResponse fetchEvidence(FetchEvidenceNetCraftReq req) {if(Objects.isNull(netCraftConfig) || Objects.isNull(netCraftConfig.getAccessNetCraftDomain())) {log.error("netCraft config is not set");return BaseResponse.fail().errorCode(ErrorCode.BUSINESS_EXCEPTION.getCode()).errorMsg("netCraft config is not set").build();}String fetch_evidence = "https://" + netCraftConfig.getAccessNetCraftDomain()+ netCraftConfig.getFETCH_EVIDENCE();Map<String, String> headers = new HashMap<>();headers.put("content-type", "application/json");headers.put("Authorization", netCraftConfig.getAccessNetCraftAuthToken());ByteArrayOutputStream  outputStream = new ByteArrayOutputStream();byte[] fileBytes;String fileName;try {outputStream =  new ByteArrayOutputStream();fileName = getFromOctetStream(fetch_evidence + "?takedown_id="+ req.getTakeDownId(), headers, outputStream);if(Objects.isNull(fileName)) {return BaseResponse.fail().errorCode(ErrorCode.BUSINESS_EXCEPTION.getCode()).errorMsg("获取netcraft证据文件失败").build();}outputStream.flush();fileBytes = outputStream.toByteArray();} catch (Exception e) {log.error("获取证据文件失败:" + e.getMessage());return BaseResponse.fail().errorCode(ErrorCode.BUSINESS_EXCEPTION.getCode()).errorMsg("获取netcraft证据文件失败").build();} finally {if(outputStream != null) {try {outputStream.close();} catch (IOException e1) {e1.printStackTrace();}}}NetCraftQueryEvidenceRsp rsp = new NetCraftQueryEvidenceRsp();if(Objects.nonNull(fileName)) {NetCraftErrorMessageRsp errorMessageRsp = JsonUtils.fromCamelJson(fileName, NetCraftErrorMessageRsp.class);if(Objects.nonNull(errorMessageRsp)&& Objects.nonNull(errorMessageRsp.getErrorCode())&& Objects.nonNull(errorMessageRsp.getErrorMessage())) {rsp.setErrorCode(errorMessageRsp.getErrorCode());rsp.setErrorMessage(errorMessageRsp.getErrorMessage());return BaseResponse.success(rsp).build();}rsp.setFileBytes(fileBytes);rsp.setFileName(fileName);return BaseResponse.success(rsp).build();}return BaseResponse.fail().errorCode(ErrorCode.BUSINESS_EXCEPTION.getCode()).errorMsg("获取netcraft证据文件失败").build();}public static String getFromOctetStream(String url, Map<String, String> headers, OutputStream outputStream) {return getFromOctetStream(url, headers, OK_HTTP_CLIENT_30s, outputStream);}public static String getFromOctetStream(String url, Map<String, String> headers, String client, OutputStream outputStream) {Request.Builder requestBuilder = new Request.Builder();requestBuilder.url(url);if (headers != null && headers.size() > 0) {for (String s : headers.keySet()) {requestBuilder.addHeader(s, headers.get(s));}}requestBuilder.get();Request req = requestBuilder.build();try (Response response = okHttpClientMap.get(client).newCall(req).execute()) {log.info("okhttp send get,resp:{}", JsonUtils.toJson(response));if (null != response.body()) {InputStream inputStream = response.body().byteStream();try {byte[] buffer = new byte[1024];int read = inputStream.read(buffer);while (read != -1) {outputStream.write(buffer, 0, read);read = inputStream.read(buffer);}} catch (Exception e) {log.error("处理返回值失败" + e.getMessage());return null;} finally {try {inputStream.close();} catch (IOException e) {e.printStackTrace();}}String contentDisposition = response.header("Content-Disposition");if (Objects.isNull(contentDisposition)) {log.error("调用netcraft获取证据接口, 获取文件名失败");return outputStream.toString();}// 解析文件名return contentDisposition.substring(contentDisposition.indexOf("filename=") + 9);}

spring上传文件大小控制

在spring配置文件application.properties中，通过配置下面两个参数的值来限制文件的大小

spring.servlet.multipart.max-file-size=-1
spring.servlet.multipart.max-request-size=-1

spring.servlet.multipart.max-file-size配置限制上传单个文件的大小，为-1代表不限制
spring.servlet.multipart.max-request-size配置限制http中上传总文件的大小，为-1代表不限制