Help Center/ Object Storage Service/ SDK Reference/ Java/ Object Download (SDK for Java)/ Creating a Signed URL for Downloading a Processed Image (SDK for Java)
Updated on 2024-06-18 GMT+08:00

Creating a Signed URL for Downloading a Processed Image (SDK for Java)

Function

This API processes images in a stable, secure, efficient, easy, and cost-effective manner. You can pass the parameters for clipping, resizing, watermarking, converting the format of, or performing other operations on images to generate a signed URL.

If you have any questions during development, post them on the Issues page of GitHub.

Restrictions

  • All image processing operations do not affect the original image.
  • Archive storage does not support image processing.
  • The processed image is directly returned to the browser for display. It is not stored in OBS, does not occupy storage space, and does not incur storage charges.

Method

obsClient.createTemporarySignature(TemporarySignatureRequest request)

Request Parameters

Table 1 createTemporarySignature

Parameter

Type

Mandatory (Yes/No)

Description

request

TemporarySignatureRequest

Yes

Explanation:

Request parameters for creating a signed URL. For details, see Table 2.

Table 2 TemporarySignatureRequest

Parameter

Type

Mandatory (Yes/No)

Description

bucketName

String

No

Explanation:

Bucket name.

Restrictions:

  • A bucket name must be unique across all accounts and regions.
  • A bucket name:
    • Must be 3 to 63 characters long and start with a digit or letter. Lowercase letters, digits, hyphens (-), and periods (.) are allowed.
    • Cannot be formatted as an IP address.
    • Cannot start or end with a hyphen (-) or period (.).
    • Cannot contain two consecutive periods (..), for example, my..bucket.
    • Cannot contain periods (.) and hyphens (-) adjacent to each other, for example, my-.bucket or my.-bucket.
  • If you repeatedly create buckets of the same name in the same region, no error will be reported and the bucket attributes comply with those set in the first creation request.

Default value:

None

objectKey

String

No

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

specialParam

SpecialParamEnum

No

Explanation:

Special parameters that may be used in the request. For details, see Table 3.

method

HttpMethodEnum

Yes

Explanation:

HTTP method. For details, see Table 3.

headers

Map<String, String>

No

Explanation:

HTTP response header list, composed of tuples. In a tuple, the String key and value indicate the name and value of the header respectively.

Default value:

None

queryParams

Map<String, Object>

No

Explanation:

Query parameters in the request. In Map<String, Object>, String indicates the key of query parameter in the request, and Object indicates the value of the query parameter.

Default value:

None

expires

long

Yes

Explanation:

Expiration time of the object. The calculation starts from the time when the object was last modified. Once the object expires, it is automatically deleted.

Restrictions:

This parameter can be configured only when uploading the object. It cannot be modified by calling a metadata modification API.

Value range:

An integer greater than 0, in days.

Default value:

None

requestDate

Date

Yes

Explanation:

Time when a request is initiated.

Default value:

None

Table 3 HttpMethodEnum & SpecialParamEnum

Operation

HTTP Request Method (Value in OBS SDK for Java)

Special Operator (Value in OBS SDK for Java)

Bucket Name Required (Yes/No)

Object Name Required (Yes/No)

Create Bucket

HttpMethodEnum.PUT

N/A

Yes

No

List Buckets

HttpMethodEnum.GET

N/A

No

No

Delete Bucket

HttpMethodEnum.DELETE

N/A

Yes

No

List Objects

HttpMethodEnum.GET

N/A

Yes

No

List Object Versions

HttpMethodEnum.GET

SpecialParamEnum.VERSIONS

Yes

No

List Multipart Uploads

HttpMethodEnum.GET

SpecialParamEnum.UPLOADS

Yes

No

Get Bucket Metadata

HttpMethodEnum.HEAD

N/A

Yes

No

Get Bucket Location

HttpMethodEnum.GET

SpecialParamEnum.LOCATION

Yes

No

Get Bucket Storageinfo

HttpMethodEnum.GET

SpecialParamEnum.STORAGEINFO

Yes

No

Set Bucket Quota

HttpMethodEnum.PUT

SpecialParamEnum.QUOTA

Yes

No

Get Bucket Quota

HttpMethodEnum.GET

SpecialParamEnum.QUOTA

Yes

No

Set Bucket Storage Policy

HttpMethodEnum.PUT

SpecialParamEnum.STORAGEPOLICY

Yes

No

Get Bucket Storage Policy

HttpMethodEnum.GET

SpecialParamEnum.STORAGEPOLICY

Yes

No

Set Bucket ACL

HttpMethodEnum.PUT

SpecialParamEnum.ACL

Yes

No

Get Bucket ACL

HttpMethodEnum.GET

SpecialParamEnum.ACL

Yes

No

Set Bucket Logging

HttpMethodEnum.PUT

SpecialParamEnum.LOGGING

Yes

No

Get Bucket Logging

HttpMethodEnum.GET

SpecialParamEnum.LOGGING

Yes

No

Set Bucket Policy

HttpMethodEnum.PUT

SpecialParamEnum.POLICY

Yes

No

Get Bucket Policy

HttpMethodEnum.GET

SpecialParamEnum.POLICY

Yes

No

Delete Bucket Policy

HttpMethodEnum.DELETE

SpecialParamEnum.POLICY

Yes

No

Set Lifecycle Rule

HttpMethodEnum.PUT

SpecialParamEnum.LIFECYCLE

Yes

No

Get Lifecycle Rule

HttpMethodEnum.GET

SpecialParamEnum.LIFECYCLE

Yes

No

Delete Lifecycle Rule

HttpMethodEnum.DELETE

SpecialParamEnum.LIFECYCLE

Yes

No

Set Website Hosting

HttpMethodEnum.PUT

SpecialParamEnum.WEBSITE

Yes

No

Get Website Hosting

HttpMethodEnum.GET

SpecialParamEnum.WEBSITE

Yes

No

Delete Website Hosting

HttpMethodEnum.DELETE

SpecialParamEnum.WEBSITE

Yes

No

Set Bucket Versioning

HttpMethodEnum.PUT

SpecialParamEnum.VERSIONING

Yes

No

Get Bucket Versioning

HttpMethodEnum.GET

SpecialParamEnum.VERSIONING

Yes

No

Set CORS Rule

HttpMethodEnum.PUT

SpecialParamEnum.CORS

Yes

No

Get CORS Rule

HttpMethodEnum.GET

SpecialParamEnum.CORS

Yes

No

Delete CORS Rule

HttpMethodEnum.DELETE

SpecialParamEnum.CORS

Yes

No

Set Bucket Tagging

HttpMethodEnum.PUT

SpecialParamEnum.TAGGING

Yes

No

Get Bucket Tagging

HttpMethodEnum.GET

SpecialParamEnum.TAGGING

Yes

No

Delete Bucket Tagging

HttpMethodEnum.DELETE

SpecialParamEnum.TAGGING

Yes

No

Upload Object

HttpMethodEnum.PUT

N/A

Yes

Yes

Append Object

HttpMethodEnum.POST

SpecialParamEnum.APPEND

Yes

Yes

Get Object

HttpMethodEnum.GET

N/A

Yes

Yes

Copy Object

HttpMethodEnum.PUT

N/A

Yes

Yes

Delete Object

HttpMethodEnum.DELETE

N/A

Yes

Yes

Delete Objects

HttpMethodEnum.POST

SpecialParamEnum.DELETE

Yes

Yes

Get Object Metadata

HttpMethodEnum.HEAD

N/A

Yes

Yes

Set Object ACL

HttpMethodEnum.PUT

SpecialParamEnum.ACL

Yes

Yes

Get Object ACL

HttpMethodEnum.GET

SpecialParamEnum.ACL

Yes

Yes

Initiate Multipart Upload

HttpMethodEnum.POST

SpecialParamEnum.UPLOADS

Yes

Yes

Upload Part

HttpMethodEnum.PUT

N/A

Yes

Yes

Copy Part

HttpMethodEnum.PUT

N/A

Yes

Yes

List Parts

HttpMethodEnum.GET

N/A

Yes

Yes

Assemble Parts

HttpMethodEnum.POST

N/A

Yes

Yes

Delete Multipart Upload

HttpMethodEnum.DELETE

N/A

Yes

Yes

Restore Archive Object

HttpMethodEnum.POST

SpecialParamEnum.RESTORE

Yes

Yes

Responses

Table 4 TemporarySignatureResponse

Parameter

Type

Description

signedUrl

String

Explanation:

The signed URL.

Default value:

None

actualSignedRequestHeaders

Map<String, String>

Explanation:

Actual headers in the request initiated using the signed URL.

Default value:

None

Code Examples

This example creates a signed URL for downloading a resized and rotated image objectname.jpg from bucket examplebucket.

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import com.obs.services.ObsClient;
import com.obs.services.exception.ObsException;
import com.obs.services.model.HttpMethodEnum;
import com.obs.services.model.TemporarySignatureRequest;
import com.obs.services.model.TemporarySignatureResponse;
import java.util.HashMap;
import java.util.Map;
public class GetObject009 {
    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 {
            // Create a signed URL for downloading a processed image.
            long expireSeconds = 3600L;
            TemporarySignatureRequest request = new TemporarySignatureRequest(HttpMethodEnum.GET, expireSeconds);
            request.setBucketName("examplebucket");
            request.setObjectKey("objectname.jpg");
            // Set image processing parameters to resize and rotate the images in the predefined sequence.
            Map<String, Object> queryParams = new HashMap<String, Object>();
            queryParams.put("x-image-process", "image/resize,m_fixed,w_100,h_100/rotate,90");
            request.setQueryParams(queryParams);
            // Generate the signed URL.
            TemporarySignatureResponse response = obsClient.createTemporarySignature(request);
            System.out.println("getSignedUrl successfully");
            System.out.println(response.getSignedUrl());
        } catch (ObsException e) {
            System.out.println("getSignedUrl 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("getSignedUrl failed");
            // Print other error information.
            e.printStackTrace();
        }
    }
}