Checking Whether an Object Exists (SDK for Java)
Function
This API checks whether an object exists. If the returned HTTP status code is 200, the object exists. If the returned HTTP status code is 404, the object or bucket does not exist.
If you have any questions during development, post them on the Issues page of GitHub.
Restrictions
- To check whether an object exists, you must be the bucket owner or have the required permission (obs:bucket:ListBucket in IAM or ListBucket in a bucket policy). For details, see Introduction to OBS Access Control, IAM Custom Policies, and Configuring an Object Policy.
- The mapping between OBS regions and endpoints must comply with what is listed in Regions and Endpoints.
Method
doesObjectExist(final GetObjectMetadataRequest request)
Request Parameters
Parameter |
Type |
Mandatory (Yes/No) |
Description |
---|---|---|---|
request |
Yes |
Explanation: Request parameters. For details, see Table 2. |
Parameter |
Type |
Mandatory (Yes/No) |
Description |
---|---|---|---|
bucketName |
String |
Yes |
Explanation: Bucket name. Restrictions:
Default value: None |
objectKey |
String |
Yes |
Explanation: Object name. An object is uniquely identified by an object name in a bucket. An object name is a complete path that does not contain the bucket name. For example, if the address for accessing the object is examplebucket.obs.ap-southeast-1.myhuaweicloud.com/folder/test.txt, the object name is folder/test.txt. Value range: The value must contain 1 to 1,024 characters. Default value: None |
versionId |
String |
No |
Explanation: Object version ID. Value range: The value must contain 32 characters. Default value: None |
userHeaders |
HashMap<String, String> |
No |
Explanation: User header list. In HashMap, the String key and value indicate the name and value of the user header field respectively. The SDK does not process the userHeaders and instead transparently transmits it to the server for later use. Value range: The value must contain 32 characters. Default value: None |
encodeHeaders |
boolean |
No |
Explanation: Whether to encode and decode HTTP headers. Value range: true: HTTP headers are encoded and decoded. false: HTTP headers are not encoded or decoded. Default value: true |
sseHeader |
No |
Explanation: Server-side decryption headers. For details, see Table 3. |
Parameter |
Type |
Mandatory (Yes/No) |
Description |
---|---|---|---|
algorithm |
Yes |
Explanation: SSE-C is used for encrypting objects on the server side. Value range: AES256, indicating AES is used to encrypt the object in SSE-C. For details, see Table 4. Default value: None |
|
sseAlgorithm |
No |
Explanation: Encryption algorithm. Restrictions: Only AES256 is supported. Value range: See Table 5. Default value: None |
|
sseCKey |
byte[] |
Yes |
Explanation: Key used for encrypting the object when SSE-C is used, in byte[] format. Default value: None |
sseCKeyBase64 |
String |
No |
Explanation: Base64-encoded key used for encrypting the object when SSE-C is used. Default value: None |
Responses
Method |
Return Value Type |
Description |
---|---|---|
doesObjectExist(final GetObjectMetadataRequest request) |
boolean |
Whether the object exists in the bucket. |
Code Examples
This example checks whether object objectname exists in bucket examplebucket.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 |
import com.obs.services.ObsClient; import com.obs.services.exception.ObsException; public class DoesObjectExist001 { public static void main(String[] args) { // Obtain an AK/SK pair using environment variables or import the AK/SK pair in other ways. Using hard coding may result in leakage. // Obtain an AK/SK pair on the management console. String ak = System.getenv("ACCESS_KEY_ID"); String sk = System.getenv("SECRET_ACCESS_KEY_ID"); // (Optional) If you are using a temporary AK/SK pair and a security token to access OBS, you are advised not to use hard coding, which may result in information leakage. // Obtain an AK/SK pair and a security token using environment variables or import them in other ways. // String securityToken = System.getenv("SECURITY_TOKEN"); // Enter the endpoint corresponding to the bucket. CN-Hong Kong is used here as an example. Replace it with the one in your actual situation. String endPoint = "https://obs.ap-southeast-1.myhuaweicloud.com"; // Obtain an endpoint using environment variables or import it in other ways. //String endPoint = System.getenv("ENDPOINT"); // Create an ObsClient instance. // Use the permanent AK/SK pair to initialize the client. ObsClient obsClient = new ObsClient(ak, sk,endPoint); // Use the temporary AK/SK pair and security token to initialize the client. // ObsClient obsClient = new ObsClient(ak, sk, securityToken, endPoint); try { // Check whether the specified object exists. System.out.println(obsClient.doesObjectExist("examplebucket", "objectname") ? "exists!" : "does not exist!"); System.out.println("doesObjectExist successfully"); } catch (ObsException e) { System.out.println("doesObjectExist failed"); // Request failed. Print the HTTP status code. System.out.println("HTTP Code:" + e.getResponseCode()); // Request failed. Print the server-side error code. System.out.println("Error Code:" + e.getErrorCode()); // Request failed. Print the error details. System.out.println("Error Message:" + e.getErrorMessage()); // Request failed. Print the request ID. System.out.println("Request ID:" + e.getErrorRequestId()); System.out.println("Host ID:" + e.getErrorHostId()); e.printStackTrace(); } catch (Exception e) { System.out.println("doesObjectExist failed"); // Print other error information. e.printStackTrace(); } } } |
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