1.匯入阿里雲oss的jar包，maven配置如下：

<dependency>
	<groupId>com.aliyun.oss</groupId>
	<artifactId>aliyun-sdk-oss</artifactId>
	<version>2.0.2</version>
</dependency>

2.程式碼部分

public class AliOssClient {
    private static final Logger LOGGER = LoggerFactory.getLogger(AliOssClient.class);

    private String accessKeyId;
    private String accessKeySecret;
    private String endpoint;

    public String getAccessKeyId() {
        return accessKeyId;
    }

    public void setAccessKeyId(String accessKeyId) {
        this.accessKeyId = accessKeyId;
    }

    public String getAccessKeySecret() {
        return accessKeySecret;
    }

    public void setAccessKeySecret(String accessKeySecret) {
        this.accessKeySecret = accessKeySecret;
    }

    public String getEndpoint() {
        return endpoint;
    }

    public void setEndpoint(String endpoint) {
        this.endpoint = endpoint;
    }
    /**
     * 上傳某個Object
     * @param resourceHost
     * @param key
     * @param inputStream
     * @return
     */
    public PutObjectResult putObject(String resourceHost, String key, InputStream inputStream,String contentType) {
        OSSClient client = new OSSClient(this.endpoint, this.accessKeyId, this.accessKeySecret);
        PutObjectResult result = null;
        try {
            // 建立上傳Object的Metadata
            ObjectMetadata meta = new ObjectMetadata();
            // 設定檔案型別
            meta.setContentType(contentType);
            // 上傳Object.
            result = client.putObject(resourceHost, key, inputStream, meta);
            LOGGER.info("上傳檔案到oss返回result={}",result);
        } catch (Exception e) {
            LOGGER.error("exception threw while putObject. resourceHost={}, key={}",
            		resourceHost, key, e);
            return result;
        }
        return result;
    }
    
    /**
     * 獲取某個Object
     * @param resourceHost
     * @param key
     * @throws IOException
     */
    public InputStream getObject(String resourceHost, String key) throws IOException{
      // 初始化OSSClient
      OSSClient client = new OSSClient(endpoint, accessKeyId, accessKeySecret);
      InputStream objectContent = null;
      try {
          // 獲取Object，返回結果為OSSObject物件
          OSSObject object = client.getObject(resourceHost, key);
          // 獲取Object的輸入流
          objectContent = object.getObjectContent();
          // 處理Object
          // 關閉流
          // objectContent.close();
          return objectContent;
      } catch (Exception e) {
        LOGGER.error("exception threw while getObject. resourceHost={}, key={}, exception={}",
        		resourceHost, key, e);
        return objectContent;
      }
    }
    
    /**
     * 分片上傳MultipartUpload
     * @param resourceHost
     * @param key
     * @param inputStream
     * @return
     */
    public String uploadFile(String resourceHost,String key,MultipartFile partFile)throws IOException {
  	  OSSClient client = new OSSClient(this.endpoint, this.accessKeyId, this.accessKeySecret);
  	  return multipartUpload(key,partFile,client,resourceHost);

    }
    

    private String multipartUpload(String key, MultipartFile partFile, OSSClient client, String bucketName) throws IOException {
        // 開始Multipart Upload
        InitiateMultipartUploadRequest initiateMultipartUploadRequest = new InitiateMultipartUploadRequest(bucketName, key);
        InitiateMultipartUploadResult initiateMultipartUploadResult = client.initiateMultipartUpload(initiateMultipartUploadRequest);
        final int partSize = 1024 * 1024 * 5;
        // 計算分塊數目
        int partCount = (int) (partFile.getSize() / partSize);
        if (partFile.getSize() % partSize != 0){
            partCount++;
        }
        // 新建一個List儲存每個分塊上傳後的ETag和PartNumber
        List<PartETag> partETags = new ArrayList<>();
        for(int i = 0; i < partCount; i++){
            // 獲取檔案流
            InputStream fis = partFile.getInputStream();
            // 跳到每個分塊的開頭
            long skipBytes =(long) partSize * i;
            fis.skip(skipBytes);

            // 計算每個分塊的大小
            long size = partSize < partFile.getSize() - skipBytes ?
                    partSize : partFile.getSize() - skipBytes;
            // 建立UploadPartRequest，上傳分塊
            UploadPartRequest uploadPartRequest = new UploadPartRequest();
            uploadPartRequest.setBucketName(bucketName);
            uploadPartRequest.setKey(key);
            uploadPartRequest.setUploadId(initiateMultipartUploadResult.getUploadId());
            uploadPartRequest.setInputStream(fis);
            uploadPartRequest.setPartSize(size);
            uploadPartRequest.setPartNumber(i + 1);
            UploadPartResult uploadPartResult = client.uploadPart(uploadPartRequest);
            // 將返回的PartETag儲存到List中。
            partETags.add(uploadPartResult.getPartETag());
            // 關閉檔案
            fis.close();
        }
        CompleteMultipartUploadRequest completeMultipartUploadRequest =
                new CompleteMultipartUploadRequest(bucketName,key, initiateMultipartUploadResult.getUploadId(), partETags);
        // 完成分塊上傳
        CompleteMultipartUploadResult completeMultipartUploadResult =
                client.completeMultipartUpload(completeMultipartUploadRequest);
        // 獲得地址
        return completeMultipartUploadResult.getKey();

    }
}
 

3.外部如何呼叫

一般  Constants.RESOURCE_PATH=“http://test.baidu.com/”作為字首一般會配在資料庫裡面，而key作為規則路徑，可自己匹配規則，a/uuid/n.pdf之類的；然後根據 url=Constants.RESOURCE_PATH + key 來取資源。

public class Test {
	public static void main(String[] args) throws IOException {
		//application/pdf
		AliOssClient client = new AliOssClient();
		client.setAccessKeyId("aliyun oss的鑑權id");
		client.setAccessKeySecret("aliyun oss的鑑權祕鑰");
		client.setEndpoint("aliyun oss地址");
		// 1.上傳pdf到OSS
		InputStream inputStream = null;
		//TODO 得到pdf輸入流
		
		PutObjectResult result = client.putObject("http://www.aliyun.com/ad", "/qwew/qwe1/1.pdf", inputStream, "application/pdf");
		// 其中 url = http://www.baidu.com/ad + /qwew/qwe1/1.pdf就是下載地址
		System.out.println("下載url是"+"http://www.aliyun.com/ad/qwew/qwe1/1.pdf");
		
		
		// 2.從OSS下載pdf
		InputStream in = client.getObject("http://www.aliyun.com/ad", "/qwew/qwe1/1.pdf");
		
		//TODO  將流轉化為pdf儲存到檔案或者flush到頁面，在頁面下載
	}
	

}