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

Updated on 2024-12-11 GMT+08:00

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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.

NOTICE:

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

Restrictions

To download an object, you must be the bucket owner or have the required permission (obs:object:GetObject in IAM or GetObject 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.

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 Objects	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.

    
     
       
       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();
        }
    }
}

      

    
   