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Torch Object StorageSDK ReferenceJavaObject InterfaceList ObjectList Objects (Java SDK)
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List Objects (Java SDK)
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This article describes how to use the TOS Java SDK listObjects interface to easily list objects in a specified bucket, list all objects, list objects with a specified prefix, list objects and subdirectories under a specified directory, etc.
Notes
- Before listing objects, your account must have the tos:ListBucket permission. For details on how to proceed, refer to the IAM policy overview.
- The current TOS now supports the new listObjectsType2 interface, whose usage is largely consistent with that of the listObjects interface. It is strongly recommended that you use the listObjectsType2 interface to achieve higher listing efficiency. For detailed usage methods, please refer to List Objects V2 (Java SDK).
Parameters
The parameters supported by the listObjects interface are as follows.
Parameter | Description |
Parameter | Description |
prefix | The prefix of the current query results. |
delimiter | Character used to group object names. |
marker | The starting point for the enumeration of objects in this instance. Initially set to null; subsequently, it may take the value of nextMarker returned by the previous request. |
maxKeys | Returns the maximum number of objects to be enumerated. A maximum of 1,000 results can be returned per request; if not specified, the default is 1,000 results. |
encodingType | Encode the returned content and specify the encoding type. |
Sample code
Simple listing
The following code demonstrates how to list up to 10 objects in the bucket-example bucket.
import com.volcengine.tos.TOSV2;
import com.volcengine.tos.TOSV2ClientBuilder;
import com.volcengine.tos.TosClientException;
import com.volcengine.tos.TosServerException;
import com.volcengine.tos.model.object.*;
public class ListObjectsBasicExample {
public static void main(String[] args) {
String endpoint = "your endpoint";
String region = "your region";
String accessKey = System.getenv("TOS_ACCESS_KEY");
String secretKey = System.getenv("TOS_SECRET_KEY");
String bucketName = "bucket-example";
int maxKeys = 10;
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try{
ListObjectsV2Input input = new ListObjectsV2Input()
.setBucket(bucketName).setMaxKeys(maxKeys);
ListObjectsV2Output output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
}
}
} catch (TosClientException e) {
System.out.println("listObjects failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("listObjects failed");
System.out.println("StatusCode: " + e.getStatusCode());
System.out.println("Code: " + e.getCode());
System.out.println("Message: " + e.getMessage());
System.out.println("RequestID: " + e.getRequestID());
} catch (Throwable t) {
System.out.println("listObjects failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
}
Paginated listing
The following code demonstrates how to list objects by page in the bucket-example bucket.
import com.volcengine.tos.TOSV2;
import com.volcengine.tos.TOSV2ClientBuilder;
import com.volcengine.tos.TosClientException;
import com.volcengine.tos.TosServerException;
import com.volcengine.tos.model.object.*;
public class ListObjectsByPageExample {
public static void main(String[] args) {
String endpoint = "your endpoint";
String region = "your region";
String accessKey = System.getenv("TOS_ACCESS_KEY");
String secretKey = System.getenv("TOS_SECRET_KEY");
String bucketName = "bucket-example";
int maxKeys = 10;
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try{
ListObjectsV2Input input = new ListObjectsV2Input()
.setBucket(bucketName).setMaxKeys(maxKeys);
ListObjectsV2Output output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
}
}
if (output.isTruncated()) {
input.setMarker(output.getNextMarker());
output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
}
}
}
}
} catch (TosClientException e) {
System.out.println("listObjects failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("listObjects failed");
System.out.println("StatusCode: " + e.getStatusCode());
System.out.println("Code: " + e.getCode());
System.out.println("Message: " + e.getMessage());
System.out.println("RequestID: " + e.getRequestID());
} catch (Throwable t) {
System.out.println("listObjects failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
}
List all objects with the specified prefix
The following code demonstrates how to list all objects with a specified prefix in the bucket-example bucket.
import com.volcengine.tos.TOSV2;
import com.volcengine.tos.TOSV2ClientBuilder;
import com.volcengine.tos.TosClientException;
import com.volcengine.tos.TosServerException;
import com.volcengine.tos.model.object.*;
public class ListObjectsByPrefixExample {
public static void main(String[] args) {
String endpoint = "your endpoint";
String region = "your region";
String accessKey = System.getenv("TOS_ACCESS_KEY");
String secretKey = System.getenv("TOS_SECRET_KEY");
String bucketName = "bucket-example";
int maxKeys = 10;
String prefix = "example_dir/";
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try{
boolean isTruncated = true;
String marker = null;
while (isTruncated) {
ListObjectsV2Input input = new ListObjectsV2Input().setBucket(bucketName)
.setMaxKeys(maxKeys).setPrefix(prefix).setMarker(marker);
ListObjectsV2Output output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
}
}
isTruncated = output.isTruncated();
marker = output.getNextMarker();
}
} catch (TosClientException e) {
System.out.println("listObjects failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("listObjects failed");
System.out.println("StatusCode: " + e.getStatusCode());
System.out.println("Code: " + e.getCode());
System.out.println("Message: " + e.getMessage());
System.out.println("RequestID: " + e.getRequestID());
} catch (Throwable t) {
System.out.println("listObjects failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
}
List all objects in the bucket
The following code demonstrates how to list all objects in the bucket-example bucket.
import com.volcengine.tos.TOSV2;
import com.volcengine.tos.TOSV2ClientBuilder;
import com.volcengine.tos.TosClientException;
import com.volcengine.tos.TosServerException;
import com.volcengine.tos.model.object.*;
public class ListObjectsAllObjectExample {
public static void main(String[] args) {
String endpoint = "your endpoint";
String region = "your region";
String accessKey = System.getenv("TOS_ACCESS_KEY");
String secretKey = System.getenv("TOS_SECRET_KEY");
String bucketName = "bucket-example";
int maxKeys = 10;
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try{
boolean isTruncated = true;
String marker = null;
while (isTruncated) {
ListObjectsV2Input input = new ListObjectsV2Input().setBucket(bucketName)
.setMaxKeys(maxKeys).setMarker(marker);
ListObjectsV2Output output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
}
}
isTruncated = output.isTruncated();
marker = output.getNextMarker();
}
} catch (TosClientException e) {
System.out.println("listObjects failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("listObjects failed");
System.out.println("StatusCode: " + e.getStatusCode());
System.out.println("Code: " + e.getCode());
System.out.println("Message: " + e.getMessage());
System.out.println("RequestID: " + e.getRequestID());
} catch (Throwable t) {
System.out.println("listObjects failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
}
List objects and subdirectories in the specified directory
TOS only supports the concept of objects. To simulate directory functionality, create a zero-byte object that ends with a forward slash (/).
You can simulate directory functionality using the two parameters Delimiter and Prefix:
- First, set Delimiter to /. By setting Prefix to empty, you can retrieve information about objects and subdirectories in the root directory.
- When Delimiter is /, by setting Prefix as a subdirectory (commonPrefixes), both the objects in the subdirectory and its subdirectories can be returned.
The following code demonstrates how to list the objects and subdirectories in the root directory of the bucket-example bucket.
import com.volcengine.tos.TOSV2;
import com.volcengine.tos.TOSV2ClientBuilder;
import com.volcengine.tos.TosClientException;
import com.volcengine.tos.TosServerException;
import com.volcengine.tos.model.object.*;
public class ListObjectsByDelimiterExample {
public static void main(String[] args) {
String endpoint = "your endpoint";
String region = "your region";
String accessKey = System.getenv("TOS_ACCESS_KEY");
String secretKey = System.getenv("TOS_SECRET_KEY");
String bucketName = "bucket-example";
int maxKeys = 10;
String delimiter = "/";
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try{
boolean isTruncated = true;
String marker = null;
while (isTruncated) {
ListObjectsV2Input input = new ListObjectsV2Input().setBucket(bucketName)
.setMaxKeys(maxKeys).setDelimiter(delimiter).setMarker(marker);
ListObjectsV2Output output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
listCommonPrefix(bucketName, maxKeys, delimiter, commonPrefix.getPrefix(), tos);
}
}
isTruncated = output.isTruncated();
marker = output.getNextMarker();
}
} catch (TosClientException e) {
System.out.println("listObjects failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("listObjects failed");
System.out.println("StatusCode: " + e.getStatusCode());
System.out.println("Code: " + e.getCode());
System.out.println("Message: " + e.getMessage());
System.out.println("RequestID: " + e.getRequestID());
} catch (Throwable t) {
System.out.println("listObjects failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
private static void listCommonPrefix(String bucketName, int maxKeys, String delimiter, String prefix, TOSV2 tos) {
boolean isTruncated = true;
String marker = null;
while (isTruncated) {
ListObjectsV2Input input = new ListObjectsV2Input().setBucket(bucketName).setMaxKeys(maxKeys)
.setDelimiter(delimiter).setMarker(marker).setPrefix(prefix);
ListObjectsV2Output output = tos.listObjects(input);
System.out.printf("listObjects succeed, is truncated? %b, next marker is %s.\n",
output.isTruncated(), output.getNextMarker());
if (output.getContents() != null) {
for (int i = 0; i < output.getContents().size(); i++) {
ListedObjectV2 object = output.getContents().get(i);
System.out.printf("Listed object, key is %s, size is %d, storageClass is %s, ETag is %s, " +
"last modified is %s, crc64 value is %s.\n", object.getKey(), object.getSize(),
object.getStorageClass(), object.getEtag(), object.getLastModified().toString(), object.getHashCrc64ecma());
}
}
if (output.getCommonPrefixes() != null) {
for (int i = 0; i < output.getCommonPrefixes().size(); i++) {
ListedCommonPrefix commonPrefix = output.getCommonPrefixes().get(i);
System.out.println("Listed commonPrefix is " + commonPrefix.getPrefix());
}
}
isTruncated = output.isTruncated();
marker = output.getNextMarker();
}
}
}
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Last updated: 2026.08.03 10:40:27
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