public interface DFsService {
    /**
     * 存儲文件
     * @param storeRequest 存儲請求
     * @throws IOException 異常
     */
    void store(StoreRequest storeRequest) throws IOException;
    /**
     * 下載文件
     * @param downloadRequest 文件下載請求
     * @throws IOException 異常
     */
    void download(DownloadRequest downloadRequest) throws IOException;
    /**
     * 獲取文件元信息
     * @param fileLocation 文件位置
     * @return 存在則返回文件元信息
     * @throws IOException 異常
     */
    Optional<FileMeta> fetchFileMeta(FileLocation fileLocation) throws IOException;
    /**
     * 清理 powerjob 認為“過期”的文件
     * 部分存儲系統(tǒng)自帶生命周期管理（如阿里云OSS，則不需要單獨實現(xiàn)該方法）
     * @param bucket bucket
     * @param days 天數(shù)，需要清理超過 X 天的文件
     */
    default void cleanExpiredFiles(String bucket, int days) {
    }
}

@Slf4j
public abstract class AbstractDFsService implements DFsService, ApplicationContextAware, DisposableBean {
    protected ApplicationContext applicationContext;
    public AbstractDFsService() {
        log.info("[DFsService] invoke [{}]'s constructor", this.getClass().getName());
    }
    abstract protected void init(ApplicationContext applicationContext);
    protected static final String PROPERTY_KEY = "oms.storage.dfs";
    protected static String fetchProperty(Environment environment, String dfsType, String key) {
        String pKey = String.format("%s.%s.%s", PROPERTY_KEY, dfsType, key);
        return environment.getProperty(pKey);
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
        log.info("[DFsService] invoke [{}]'s setApplicationContext", this.getClass().getName());
        init(applicationContext);
    }
}

@Slf4j
@Priority(value = Integer.MAX_VALUE - 1)
@Conditional(AliOssService.AliOssCondition.class)
public class AliOssService extends AbstractDFsService {
    private static final String TYPE_ALI_OSS = "alioss";
    private static final String KEY_ENDPOINT = "endpoint";
    private static final String KEY_BUCKET = "bucket";
    private static final String KEY_CREDENTIAL_TYPE = "credential_type";
    private static final String KEY_AK = "ak";
    private static final String KEY_SK = "sk";
    private static final String KEY_TOKEN = "token";
    private OSS oss;
    private String bucket;
    private static final int DOWNLOAD_PART_SIZE = 10240;
    private static final String NO_SUCH_KEY = "NoSuchKey";
    //......
    void initOssClient(String endpoint, String bucket, String mode, String ak, String sk, String token) throws Exception {
        log.info("[AliOssService] init OSS by config: endpoint={},bucket={},credentialType={},ak={},sk={},token={}", endpoint, bucket, mode, ak, sk, token);
        if (StringUtils.isEmpty(bucket)) {
            throw new IllegalArgumentException("'oms.storage.dfs.alioss.bucket' can't be empty, please creat a bucket in aliyun oss console then config it to powerjob");
        }
        this.bucket = bucket;
        CredentialsProvider credentialsProvider;
        CredentialType credentialType = CredentialType.parse(mode);
        switch (credentialType) {
            case PWD:
                credentialsProvider = new DefaultCredentialProvider(ak, sk, token);
                break;
            case SYSTEM_PROPERTY:
                credentialsProvider = CredentialsProviderFactory.newSystemPropertiesCredentialsProvider();
                break;
            default:
                credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        }
        this.oss = new OSSClientBuilder().build(endpoint, credentialsProvider);
        log.info("[AliOssService] initialize successfully, THIS_WILL_BE_THE_STORAGE_LAYER.");
    }
    //......    
}

@Override
    public void store(StoreRequest storeRequest) throws IOException {

        ObjectMetadata objectMetadata = new ObjectMetadata();

        PutObjectRequest putObjectRequest = new PutObjectRequest(bucket, parseFileName(storeRequest.getFileLocation()), storeRequest.getLocalFile(), objectMetadata);
        oss.putObject(putObjectRequest);
    }

@Override
    public void download(DownloadRequest downloadRequest) throws IOException {

        FileLocation dfl = downloadRequest.getFileLocation();
        DownloadFileRequest downloadFileRequest = new DownloadFileRequest(bucket, parseFileName(dfl), downloadRequest.getTarget().getAbsolutePath(), DOWNLOAD_PART_SIZE);
        try {
            FileUtils.forceMkdirParent(downloadRequest.getTarget());
            oss.downloadFile(downloadFileRequest);
        } catch (Throwable t) {
            ExceptionUtils.rethrow(t);
        }
    }

@Override
    public Optional<FileMeta> fetchFileMeta(FileLocation fileLocation) throws IOException {
        try {
            ObjectMetadata objectMetadata = oss.getObjectMetadata(bucket, parseFileName(fileLocation));
            return Optional.ofNullable(objectMetadata).map(ossM -> {

                Map<String, Object> metaInfo = Maps.newHashMap();
                metaInfo.putAll(ossM.getRawMetadata());
                if (ossM.getUserMetadata() != null) {
                    metaInfo.putAll(ossM.getUserMetadata());
                }

                return new FileMeta()
                        .setLastModifiedTime(ossM.getLastModified())
                        .setLength(ossM.getContentLength())
                        .setMetaInfo(metaInfo);
            });
        } catch (OSSException oe) {
            String errorCode = oe.getErrorCode();
            if (NO_SUCH_KEY.equalsIgnoreCase(errorCode)) {
                return Optional.empty();
            }
            ExceptionUtils.rethrow(oe);
        }
        return Optional.empty();
    }

@Override
    public void cleanExpiredFiles(String bucket, int days) {
        /*
        阿里云 OSS 自帶生命周期管理，請參考文檔進行配置，代碼層面不進行實現(xiàn)（浪費服務(wù)器資源）https://help.aliyun.com/zh/oss/user-guide/overview-54
        阿里云 OSS 自帶生命周期管理，請參考文檔進行配置，代碼層面不進行實現(xiàn)（浪費服務(wù)器資源）https://help.aliyun.com/zh/oss/user-guide/overview-54
        阿里云 OSS 自帶生命周期管理，請參考文檔進行配置，代碼層面不進行實現(xiàn)（浪費服務(wù)器資源）https://help.aliyun.com/zh/oss/user-guide/overview-54
         */
    }

protected void init(ApplicationContext applicationContext) {
        Environment environment = applicationContext.getEnvironment();

        String endpoint = fetchProperty(environment, TYPE_ALI_OSS, KEY_ENDPOINT);
        String bkt = fetchProperty(environment, TYPE_ALI_OSS, KEY_BUCKET);
        String ct = fetchProperty(environment, TYPE_ALI_OSS, KEY_CREDENTIAL_TYPE);
        String ak = fetchProperty(environment, TYPE_ALI_OSS, KEY_AK);
        String sk = fetchProperty(environment, TYPE_ALI_OSS, KEY_SK);
        String token = fetchProperty(environment, TYPE_ALI_OSS, KEY_TOKEN);

        try {
            initOssClient(endpoint, bkt, ct, ak, sk, token);
        } catch (Exception e) {
            ExceptionUtils.rethrow(e);
        }
    }