使用Java获取S3存储桶中所有项目列表的最简单方法是什么？
List<S3ObjectSummary> s3objects = s3.listObjects(bucketName,prefix).getObjectSummaries();
此示例仅返回1000个项目。
答案 0 :(得分：87)
这可能是一种解决方法，但这解决了我的问题：
ObjectListing listing = s3.listObjects( bucketName, prefix );
List<S3ObjectSummary> summaries = listing.getObjectSummaries();
while (listing.isTruncated()) {
listing = s3.listNextBatchOfObjects (listing);
summaries.addAll (listing.getObjectSummaries());
}
答案 1 :(得分：17)
这直接来自AWS文档：
AmazonS3 s3client = new AmazonS3Client(new ProfileCredentialsProvider());
ListObjectsRequest listObjectsRequest = new ListObjectsRequest()
.withBucketName(bucketName)
.withPrefix("m");
ObjectListing objectListing;
do {
objectListing = s3client.listObjects(listObjectsRequest);
for (S3ObjectSummary objectSummary :
objectListing.getObjectSummaries()) {
System.out.println( " - " + objectSummary.getKey() + " " +
"(size = " + objectSummary.getSize() +
")");
}
listObjectsRequest.setMarker(objectListing.getNextMarker());
} while (objectListing.isTruncated());
答案 2 :(得分：10)
我正在处理由我们的系统生成的大量对象;我们更改了存储数据的格式，需要检查每个文件，确定哪些文件采用旧格式，然后进行转换。还有其他方法可以做到这一点，但这个方法与你的问题有关。
ObjectListing list = amazonS3Client.listObjects(contentBucketName, contentKeyPrefix);
do {
List<S3ObjectSummary> summaries = list.getObjectSummaries();
for (S3ObjectSummary summary : summaries) {
String summaryKey = summary.getKey();
/* Retrieve object */
/* Process it */
}
list = amazonS3Client.listNextBatchOfObjects(list);
}while (list.isTruncated());
答案 3 :(得分：7)
作为一个稍微更简洁的解决方案，列出可能被截断的S3对象：
ListObjectsRequest request = new ListObjectsRequest().withBucketName(bucketName);
ObjectListing listing = null;
while((listing == null) || (request.getMarker() != null)) {
listing = s3Client.listObjects(request);
// do stuff with listing
request.setMarker(listing.getNextMarker());
}
答案 4 :(得分：7)
使用AWS SDK for Java列出密钥
http://docs.aws.amazon.com/AmazonS3/latest/dev/ListingObjectKeysUsingJava.html
w:ins答案 5 :(得分：7)
对于那些在2018年以上阅读此书的人。有两种新的无分页操作的API：一种适用于Java 1.x的AWS开发工具包，另一种适用于2.x的API。
Java SDK中有一个new API，可让您遍历S3存储桶中的对象而无需处理分页：
AmazonS3 s3 = AmazonS3ClientBuilder.standard().build();
S3Objects.inBucket(s3, "the-bucket").forEach((S3ObjectSummary objectSummary) -> {
// TODO: Consume `objectSummary` the way you need
System.out.println(objectSummary.key);
});
此迭代很懒：
S3ObjectSummary的列表将根据需要懒惰地获取，一次一页。可以使用withBatchSize(int)方法控制页面的大小。
API已更改，因此这是SDK 2.x版本：
S3Client client = S3Client.builder().region(Region.US_EAST_1).build();
ListObjectsV2Request request = ListObjectsV2Request.builder().bucket("the-bucket").prefix("the-prefix").build();
ListObjectsV2Iterable response = client.listObjectsV2Paginator(request);
for (ListObjectsV2Response page : response) {
page.contents().forEach((S3Object object) -> {
// TODO: Consume `object` the way you need
System.out.println(object.key());
});
}
调用该操作时，将返回此类的实例。此时，尚未进行任何服务调用，因此无法保证该请求有效。在迭代过程中，SDK将通过进行服务调用来延迟加载响应页面，直到没有页面可用或您的迭代停止为止。如果您的请求中有错误，则只有在开始遍历可迭代对象之后，您才会看到失败。
答案 6 :(得分：4)
AmazonS3Client s3Client = new AmazonS3Client(new BasicAWSCredentials( ....
ObjectListing images = s3Client.listObjects(bucketName);
List<S3ObjectSummary> list = images.getObjectSummaries();
for(S3ObjectSummary image: list) {
S3Object obj = s3Client.getObject(bucketName, image.getKey());
writeToFile(obj.getObjectContent());
}
答案 7 :(得分：3)
我知道这是一篇旧帖子，但这对任何人都有用：2.1版的Java / Android SDK提供了一个名为setMaxKeys的方法。像这样：
s3objects.setMaxKeys(arg0)
您现在可能已找到解决方案，但请检查一个答案是否正确，以便将来可能对其他人有所帮助。
答案 8 :(得分：3)
这对我有用。
Thread thread = new Thread(new Runnable(){
@Override
public void run() {
try {
List<String> listing = getObjectNamesForBucket(bucket, s3Client);
Log.e(TAG, "listing "+ listing);
}
catch (Exception e) {
e.printStackTrace();
Log.e(TAG, "Exception found while listing "+ e);
}
}
});
thread.start();
private List<String> getObjectNamesForBucket(String bucket, AmazonS3 s3Client) {
ObjectListing objects=s3Client.listObjects(bucket);
List<String> objectNames=new ArrayList<String>(objects.getObjectSummaries().size());
Iterator<S3ObjectSummary> oIter=objects.getObjectSummaries().iterator();
while (oIter.hasNext()) {
objectNames.add(oIter.next().getKey());
}
while (objects.isTruncated()) {
objects=s3Client.listNextBatchOfObjects(objects);
oIter=objects.getObjectSummaries().iterator();
while (oIter.hasNext()) {
objectNames.add(oIter.next().getKey());
}
}
return objectNames;
}
答案 9 :(得分：0)
您不想一次列出存储桶中的所有1000个对象。一个更可靠的解决方案是一次最多获取10个对象。您可以使用withMaxKeys方法。
以下代码创建一个S3客户端，一次获取10个或更少的对象，并根据前缀进行过滤，并为获取的对象生成pre-signed url：
import com.amazonaws.HttpMethod;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.*;
import java.net.URL;
import java.util.Date;
/**
* @author shabab
* @since 21 Sep, 2020
*/
public class AwsMain {
static final String ACCESS_KEY = "";
static final String SECRET = "";
static final Regions BUCKET_REGION = Regions.DEFAULT_REGION;
static final String BUCKET_NAME = "";
public static void main(String[] args) {
BasicAWSCredentials awsCreds = new BasicAWSCredentials(ACCESS_KEY, SECRET);
try {
final AmazonS3 s3Client = AmazonS3ClientBuilder
.standard()
.withRegion(BUCKET_REGION)
.withCredentials(new AWSStaticCredentialsProvider(awsCreds))
.build();
ListObjectsV2Request req = new ListObjectsV2Request().withBucketName(BUCKET_NAME).withMaxKeys(10);
ListObjectsV2Result result;
do {
result = s3Client.listObjectsV2(req);
result.getObjectSummaries()
.stream()
.filter(s3ObjectSummary -> {
return s3ObjectSummary.getKey().contains("Market-subscriptions/")
&& !s3ObjectSummary.getKey().equals("Market-subscriptions/");
})
.forEach(s3ObjectSummary -> {
GeneratePresignedUrlRequest generatePresignedUrlRequest =
new GeneratePresignedUrlRequest(BUCKET_NAME, s3ObjectSummary.getKey())
.withMethod(HttpMethod.GET)
.withExpiration(getExpirationDate());
URL url = s3Client.generatePresignedUrl(generatePresignedUrlRequest);
System.out.println(s3ObjectSummary.getKey() + " Pre-Signed URL: " + url.toString());
});
String token = result.getNextContinuationToken();
req.setContinuationToken(token);
} while (result.isTruncated());
} catch (SdkClientException e) {
e.printStackTrace();
}
}
private static Date getExpirationDate() {
Date expiration = new java.util.Date();
long expTimeMillis = expiration.getTime();
expTimeMillis += 1000 * 60 * 60;
expiration.setTime(expTimeMillis);
return expiration;
}
}
答案 10 :(得分：-1)
试试这个
public void getObjectList(){
System.out.println("Listing objects");
ObjectListing objectListing = s3.listObjects(new ListObjectsRequest()
.withBucketName(bucketName)
.withPrefix("ads"));
for (S3ObjectSummary objectSummary : objectListing.getObjectSummaries()) {
System.out.println(" - " + objectSummary.getKey() + " " +
"(size = " + objectSummary.getSize() + ")");
}
}
您可以使用特定前缀对存储桶中的所有对象进行操作。