Add S3Client listObjects support in S3Template (#831)

Author: alexisgra

spring-cloud-aws-s3-parent/spring-cloud-aws-s3/src/main/java/io/awspring/cloud/s3/S3Operations.java

@@ -18,6 +18,7 @@
 import java.io.InputStream;
 import java.net.URL;
 import java.time.Duration;
+import java.util.List;
 import org.springframework.lang.Nullable;
 import software.amazon.awssdk.services.s3.S3Client;
 import software.amazon.awssdk.services.s3.model.CreateBucketResponse;
@@ -60,7 +61,17 @@ public interface S3Operations {
 	 * @param s3Url - the S3 url s3://bucket/key
 	 */
 	void deleteObject(String s3Url);
-
+	
+	/**
+	 * Returns some or all (up to 1,000) of the objects in a bucket.
+	 * Does not handle pagination. If you need pagination you should use {@link S3PathMatchingResourcePatternResolver} or {@link S3Client}
+	 *
+	 * @param bucketName - the bucket name
+	 * @param prefix - objects prefix
+	 * @return list of {@link S3Resource}
+	 */
+	List<S3Resource> listObjects(String bucketName, String prefix);
+	
 	/**
 	 * Stores a Java object in a S3 bucket. Uses {@link S3ObjectConverter} for serialization.
 	 *

spring-cloud-aws-s3-parent/spring-cloud-aws-s3/src/main/java/io/awspring/cloud/s3/S3Template.java

@@ -19,11 +19,16 @@
 import java.io.OutputStream;
 import java.net.URL;
 import java.time.Duration;
+import java.util.List;
+import java.util.stream.Collectors;
+
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StreamUtils;
 import software.amazon.awssdk.services.s3.S3Client;
 import software.amazon.awssdk.services.s3.model.GetObjectRequest;
+import software.amazon.awssdk.services.s3.model.ListObjectsV2Request;
+import software.amazon.awssdk.services.s3.model.ListObjectsV2Response;
 import software.amazon.awssdk.services.s3.model.PutObjectRequest;
 import software.amazon.awssdk.services.s3.presigner.S3Presigner;
 import software.amazon.awssdk.services.s3.presigner.model.GetObjectPresignRequest;
@@ -84,7 +89,19 @@ public void deleteObject(String s3Url) {
 		Location location = Location.of(s3Url);
 		this.deleteObject(location.getBucket(), location.getObject());
 	}
-
+	
+	@Override
+	public List<S3Resource> listObjects(String bucketName, String prefix) {
+		Assert.notNull(bucketName, "bucketName is required");
+		Assert.notNull(prefix, "prefix is required");
+		
+		final ListObjectsV2Request request = ListObjectsV2Request.builder().bucket(bucketName).prefix(prefix).build();
+		final ListObjectsV2Response response = s3Client.listObjectsV2(request);
+		
+		return response.contents().stream()
+			.map(s3Object -> new S3Resource(bucketName, s3Object.key(), s3Client, s3OutputStreamProvider)).toList();
+	}
+	
 	@Override
 	public S3Resource store(String bucketName, String key, Object object) {
 		Assert.notNull(bucketName, "bucketName is required");

spring-cloud-aws-s3-parent/spring-cloud-aws-s3/src/test/java/io/awspring/cloud/s3/S3TemplateIntegrationTests.java

@@ -26,6 +26,8 @@
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.time.Duration;
+import java.util.List;
+
 import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 import org.apache.http.client.methods.HttpGet;
@@ -147,6 +149,20 @@ void deletesObjectByS3Url() {
 				.isThrownBy(() -> client.headObject(r -> r.bucket(BUCKET_NAME).key("key.txt")));
 	}
 
+	@Test
+	void listObjects() throws IOException {
+		client.putObject(r -> r.bucket(BUCKET_NAME).key("hello-en.txt"), RequestBody.fromString("hello"));
+		client.putObject(r -> r.bucket(BUCKET_NAME).key("hello-fr.txt"), RequestBody.fromString("bonjour"));
+		client.putObject(r -> r.bucket(BUCKET_NAME).key("bye.txt"), RequestBody.fromString("bye"));
+		
+		List<S3Resource> resources = s3Template.listObjects(BUCKET_NAME, "hello");
+		assertThat(resources.size()).isEqualTo(2);
+
+		// According to the S3Client doc : "Objects are returned sorted in an ascending order of the respective key names in the list."
+		assertThat(resources).extracting(S3Resource::getInputStream).map(is -> new String(is.readAllBytes(), StandardCharsets.UTF_8))
+			.containsExactly("hello", "bonjour");
+	}
+	
 	@Test
 	void storesObject() throws IOException {
 		S3Resource storedObject = s3Template.store(BUCKET_NAME, "person.json", new Person("John", "Doe"));