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:xxxx
  accessKey: xxxxxxxx
  secretKey: xxxxxxxxxxx
  bucket: 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 {
  @Resource
   private 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。