java oss分片上传

Java SDK for OSS 提供了分片上传对象的功能，可以将大文件切分成多个小块进行上传，以提高上传速度和可靠性。以下是 Java SDK for OSS 分片上传的简单示例：

import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.model.*;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class OSSMultipartUploadDemo {

    private static String endpoint = "yourEndpoint";
    private static String accessKeyId = "yourAccessKeyId";
    private static String accessKeySecret = "yourAccessKeySecret";
    private static String bucketName = "yourBucketName";
    private static String objectName = "yourObjectName";
    private static String uploadFilePath = "yourUploadFilePath";

    public static void main(String[] args) {

        // 创建OSSClient实例
        OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);

        // 初始化分片上传
        InitiateMultipartUploadRequest initiateMultipartUploadRequest =
                new InitiateMultipartUploadRequest(bucketName, objectName);
        InitiateMultipartUploadResult initiateMultipartUploadResult =
                ossClient.initiateMultipartUpload(initiateMultipartUploadRequest);
        String uploadId = initiateMultipartUploadResult.getUploadId();

        // 计算文件分片数
        final long partSize = 1024 * 1024L; // 设置分片大小为1MB
        final File uploadFile = new File(uploadFilePath);
        long fileLength = uploadFile.length();
        int partCount = (int) (fileLength / partSize);
        if (fileLength % partSize != 0) {
            partCount++;
        }

        // 上传分片
        List<PartETag> partETags = new ArrayList<>();
        for (int i = 0; i < partCount; i++) {
            long startPos = i * partSize;
            long curPartSize = (i + 1 == partCount) ? fileLength - startPos : partSize;
            UploadPartRequest uploadPartRequest = new UploadPartRequest();
            uploadPartRequest.setBucketName(bucketName);
            uploadPartRequest.setKey(objectName);
            uploadPartRequest.setUploadId(uploadId);
            uploadPartRequest.setPartNumber(i + 1);
            uploadPartRequest.setInputStream(FileUtils.openInputStream(uploadFile));
            uploadPartRequest.setPartSize(curPartSize);
            uploadPartRequest.setOffset(startPos);
            UploadPartResult uploadPartResult = ossClient.uploadPart(uploadPartRequest);
            partETags.add(uploadPartResult.getPartETag());
        }

        // 完成分片上传
        CompleteMultipartUploadRequest completeMultipartUploadRequest =
                new CompleteMultipartUploadRequest(bucketName, objectName, uploadId, partETags);
        CompleteMultipartUploadResult completeMultipartUploadResult =
                ossClient.completeMultipartUpload(completeMultipartUploadRequest);

        // 关闭OSSClient
        ossClient.shutdown();

        System.out.println("File upload successfully!");
    }
}

以上代码中，首先创建了一个 OSSClient 实例，然后调用 `initiateMultipartUpload` 方法初始化分片上传，并保存返回的 `uploadId`。接下来计算文件分片数，循环上传每个分片，并将每个分片的 `PartETag` 对象添加到 `partETags` 列表中。最后调用 `completeMultipartUpload` 方法完成分片上传。

需要注意的是，OSS 对象的大小必须大于100KB，否则不能进行分片上传。而且，分片上传必须按照指定的顺序上传，每个分片的大小必须相同。