一、前言
有时在项目中需要使用一些存储系统来存储文件，那么当项目要接入obs作为存储系统时，就会利用obs来进行文件的上传下载，具体实现如下。

二、如何通过obs实现文件的上传下载？
1.添加相关的obs的maven依赖。

 <dependency><groupId>com.huaweicloud</groupId><artifactId>esdk-obs-java-bundle</artifactId><version>3.23.9</version></dependency>

2.配置obs客户端连接。

@Configuration  
@Data
public class OBSConfig {  @Value("${obs.accessKey}")  private String accessKey;  @Value("${obs.secretKey}")  private String secretKey;  @Value("${obs.endpoint}")  private String endpoint;  @Value("${obs.bucket}")private String bucketName;}  

3.在YAML添加obs配置。

obs:endpoint: http://xxxxxx:xxxxaccessKey: xxxxxxxxsecretKey: xxxxxxxxxxxbucket: my-bucket

4.定义obs工具类，代码如下：

import com.obs.services.ObsClient;
import com.obs.services.exception.ObsException;
import com.obs.services.model.CompleteMultipartUploadRequest;
import com.obs.services.model.CompleteMultipartUploadResult;
import com.obs.services.model.ObjectMetadata;
import com.obs.services.model.PutObjectRequest;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;import java.io.File;
import java.io.InputStream;
import java.util.UUID;@Component
public class ObsUtil {@Resourceprivate OBSConfig  oBSConfig；private ObsClient obsClient;public ObsClient getClient() {if (obsClient == null) {obsClient = new ObsClient(oBSConfig.getAccessKey, oBSConfig.getSecretKey, oBSConfig.getEndPoint);}return obsClient;}/*** 上传文件到OBS** @param file 待上传的文件* @return 返回文件的访问路径*/public String uploadFile(File file) {try (ObsClient obsClient = getObsClient()) {// 生成唯一的文件名String fileName = UUID.randomUUID().toString() + "-" + file.getName();PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, fileName, file);// 设置元数据（可选）ObjectMetadata metadata = new ObjectMetadata();metadata.setContentType("application/octet-stream");putObjectRequest.setMetadata(metadata);obsClient.putObject(putObjectRequest);return endpoint + "/" + bucketName + "/" + fileName;} catch (ObsException e) {throw new RuntimeException("上传文件失败：" + e.getMessage(), e);}}/*** 上传文件流到OBS** @param inputStream 文件输入流* @param fileName    文件名* @return 返回文件的访问路径*/public String uploadInputStream(InputStream inputStream, String fileName) {try (ObsClient obsClient = getObsClient()) {// 生成唯一的文件名String objectKey = UUID.randomUUID().toString() + "-" + fileName;PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, objectKey, inputStream);// 设置元数据（可选）ObjectMetadata metadata = new ObjectMetadata();metadata.setContentType("application/octet-stream");putObjectRequest.setMetadata(metadata);obsClient.putObject(putObjectRequest);return endpoint + "/" + bucketName + "/" + objectKey;} catch (ObsException e) {throw new RuntimeException("上传文件流失败：" + e.getMessage(), e);}}/*** 下载文件** @param objectKey 对象键（文件名）* @param savePath  保存路径*/public Inputstream downloadFile(String objectKey, String savePath) {try (ObsClient obsClient = getObsClient()) {GetObjectRequest request = new GetObjectRequest();request.setBucketName(StringUtils.isEmpty(bucket) ? oBSConfig.getBucket : bucket);String objectName = (originFilePath == null ? "" : originFilePath) + fileName;objectName = objectName.charAt(0) == '/' ? objectName.substring(1) : objectName;request.setObjectKey(objectName);if (offset != null) {request.setRangeStart(offset);if (length != null) {request.setRangeEnd(offset + length);}}ObsObject object = client.getObject(request);return object.getObjectContent();} catch (ObsException e) {throw new RuntimeException("下载文件失败：" + e.getMessage(), e);}}/*** 删除文件** @param objectKey 对象键（文件名）*/public void deleteFile(String objectKey) {try (ObsClient obsClient = getObsClient()) {obsClient.deleteObject(bucketName, objectKey);} catch (ObsException e) {throw new RuntimeException("删除文件失败：" + e.getMessage(), e);}}
}

5.文件上传接口实现示例:

@RestController  
@RequestMapping("/obs")  
public class OBSUploadController {  @Autowired  private ObsUtil obsUtil ;  @PostMapping("/upload")  public ResponseEntity<String> uploadFile(  @RequestParam("file") MultipartFile file) {  try {  obsUtil.uploadFile(file.getInputStream(),"xxxx");  return ResponseEntity.ok("OBS路径: " + objectKey);  } catch (ObsException e) {  return ResponseEntity.status(e.getResponseCode())  .body("OBS服务异常: " + e.getErrorMessage());  } catch (Exception e) {  return ResponseEntity.internalServerError()  .body("上传失败: " + e.getMessage());  }  }  
}  

有兴趣的可以试一试。