在AWS CLI的命令行中，使用ls加——summary。它将为您提供所有项目的列表以及特定bucket中的文档总数。我还没有尝试过包含子桶的桶:

aws s3 ls "s3://MyBucket" --summarize

这可能会花费一些时间(列出我16+K的文档大约需要4分钟)，但这比一次计算1K要快。

2021的答案

该信息现在显示在AWS仪表板中。只需导航到桶并单击Metrics选项卡。

没有一个API会给你一个计数，因为真的没有任何亚马逊特定的API来做这件事。您只需运行一个list-contents并计算返回的结果的数量。

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;
    }
}

如果你进入s3控制台的“Management”选项卡，然后点击“Metrics”，你可以很容易地获得总数和历史记录……选项卡的屏幕截图