api将以1000为增量返回列表。检查IsTruncated属性，看看是否还有更多。如果有，您需要进行另一次调用，并在下次调用时传递您获得的最后一个键作为Marker属性。然后继续这样循环，直到IsTruncated为false。

有关更多信息，请参阅亚马逊文档:遍历多页结果

您可以只执行这个cli命令来获取桶或特定文件夹中的总文件计数

扫描整个桶

aws s3api list-objects-v2 --bucket testbucket | grep "Key" | wc -l
aws s3api list-objects-v2 --bucket BUCKET_NAME | grep "Key" | wc -l

可以使用该命令获取详细信息

aws s3api list-objects-v2 --bucket BUCKET_NAME

扫描特定文件夹

aws s3api list-objects-v2 --bucket testbucket --prefix testfolder --start-after testfolder/ | grep "Key" | wc -l

aws s3api list-objects-v2 --bucket BUCKET_NAME --prefix FOLDER_NAME --start-after FOLDER_NAME/ | grep "Key" | wc -l

现在S3 API有一个简单的解决方案(在AWS cli中可用):

aws s3api list-objects --bucket BUCKETNAME --output json --query "[length(Contents[])]"

或针对特定文件夹:

aws s3api list-objects --bucket BUCKETNAME --prefix "folder/subfolder/" --output json --query "[length(Contents[])]"

以下是如何使用java客户端。

<dependency>
    <groupId>com.amazonaws</groupId>
    <artifactId>aws-java-sdk-s3</artifactId>
    <version>1.11.519</version>
</dependency>

import com.amazonaws.ClientConfiguration;
import com.amazonaws.Protocol;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.ObjectListing;

public class AmazonS3Service {

    private static final String S3_ACCESS_KEY_ID = "ACCESS_KEY";
    private static final String S3_SECRET_KEY = "SECRET_KEY";
    private static final String S3_ENDPOINT = "S3_URL";

    private AmazonS3 amazonS3;

    public AmazonS3Service() {
        ClientConfiguration clientConfiguration = new ClientConfiguration();
        clientConfiguration.setProtocol(Protocol.HTTPS);
        clientConfiguration.setSignerOverride("S3SignerType");
        BasicAWSCredentials credentials = new BasicAWSCredentials(S3_ACCESS_KEY_ID, S3_SECRET_KEY);
        AWSStaticCredentialsProvider credentialsProvider = new AWSStaticCredentialsProvider(credentials);
        AmazonS3ClientBuilder.EndpointConfiguration endpointConfiguration = new AmazonS3ClientBuilder.EndpointConfiguration(S3_ENDPOINT, null);
        amazonS3 = AmazonS3ClientBuilder.standard().withCredentials(credentialsProvider).withClientConfiguration(clientConfiguration)
                .withPathStyleAccessEnabled(true).withEndpointConfiguration(endpointConfiguration).build();
    }

    public int countObjects(String bucketName) {
        int count = 0;
        ObjectListing objectListing = amazonS3.listObjects(bucketName);
        int currentBatchCount = objectListing.getObjectSummaries().size();
        while (currentBatchCount != 0) {
            count += currentBatchCount;
            objectListing = amazonS3.listNextBatchOfObjects(objectListing);
            currentBatchCount = objectListing.getObjectSummaries().size();
        }
        return count;
    }
}

@Mayank Jaiswal提到的关于使用cloudwatch指标的问题实际上不应该是一个问题。如果你没有得到结果，那可能是因为你的范围不够广。现在是11月3日，无论我做什么尝试，我都没有得到结果。我打开s3桶，查看计数，“对象总数”计数的最后一个记录是11月1日。

下面是cloudwatch解决方案使用javascript aws-sdk的样子:

import aws from 'aws-sdk';
import { startOfMonth } from 'date-fns';

const region = 'us-east-1';
const profile = 'default';
const credentials = new aws.SharedIniFileCredentials({ profile });
aws.config.update({ region, credentials });

export const main = async () => {
  const cw = new aws.CloudWatch();
  const bucket_name = 'MY_BUCKET_NAME';

  const end = new Date();
  const start = startOfMonth(end);

  const results = await cw
    .getMetricStatistics({
      // @ts-ignore
      Namespace: 'AWS/S3',
      MetricName: 'NumberOfObjects',
      Period: 3600 * 24,
      StartTime: start.toISOString(),
      EndTime: end.toISOString(),
      Statistics: ['Average'],
      Dimensions: [
        { Name: 'BucketName', Value: bucket_name },
        { Name: 'StorageType', Value: 'AllStorageTypes' },
      ],
      Unit: 'Count',
    })
    .promise();

  console.log({ results });
};

main()
  .then(() => console.log('Done.'))
  .catch((err) => console.error(err));

请注意两点:

范围的开始被设置为月初 周期设置为一天。如果少了一点，您可能会得到一个错误，说您请求了太多的数据点。

您可以使用s3的AWS cloudwatch指标来查看每个桶的确切计数。