Download Object

The SDKs present in the section will allow you to download a particular object, or version of the object. The Bucket reference used in the below code snippet is the component instance.

The first step of the download operation is a GET operation that retrieves the required object from the bucket.

To be able to download an object, the requester must have READ access permissions. However, owners of the bucket do have the option to grant READ access permissions to users, allowing them to download the object without using the required response headers.

If Versioning is enabled for your bucket, you need to pass the versionId to download the particular version of the object. If no versionId is passed, then by default, the latest version of the object will be downloaded.

If Versioning was enabled for a bucket, then disabled. By default, the principal first object will be downloaded. To ensure you download the latest version of this object, you need to pass the versionId param with the value “topVersion”.

Ensure the following packages are imported

    

        
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         import java.nio.file.Path;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;
import java.io.*;
    

    

        
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         InputStream dataStream = bucket.getObject("sam/out/sample.txt");
// download the object to your local machine
Path path = Path.of("file_path");  // specify a path to store the downloaded object
Files.copy(dataStream, path, StandardCopyOption.REPLACE_EXISTING);
    

Download a Portion of the Object

The following SDK implements the setRange() method. This method allows you to download a specific range of bytes of an object.

Ensure the following packages are imported

    

        
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         import com.zc.component.stratus.beans.ZCGetObjectOptions;
import java.nio.file.Path;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;
import java.io.*;
    

    

        
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         // add download options
ZCGetObjectOptions options = ZCGetObjectOptions.getInstance();
options.setVersionId("3yt5ehjbjghds3i28");
options.setRange("20-200"); // start and end range of the object in bytes
InputStream dataStream = bucket.getObject("sam/out/sample.txt", options);
// download the object to your local machine
Path path = Path.of("file_path"); // specify a path to store the downloaded object
Files.copy(dataStream, path, StandardCopyOption.REPLACE_EXISTING);
    

Download an Object Using Transfer Manager

In this section, we are going to go over SDK methods that will allow you to successfully download large objects from Stratus to your local system using Transfer Manager technique. Transfer Manager is an operation where the large object is split into multiple byte ranges using the start and end bytes range of the object. Each of the object’s parts is then returned as a stream, and they are downloaded to your local system.

Create Transfer Manager Instance

Ensure the following packages are imported

    

        
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         import com.zc.component.stratus.transfer.ZCTransferManager;
    

    

        
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         ZCTransferManager transferManager= ZCTransferManager.getInstance(bucket);
    

Download Object as Iterable Part Streams

Ensure the following packages are imported

    

        
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         import java.nio.file.StandardOpenOption;
import java.nio.file.Files;
import java.util.Iterator;
import java.nio.file.Path;
import java.io.*;
    

    

        
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         Iterable <InputStream> Iterable = transferManager.getIterableObject("sam/out/sample.txt", 100 L);
Path path = Path.of("file_path");
Iterator <InputStream> res = Iterable.iterator();
while (res.hasNext()) {
    InputStream data = res.next(); // get each part of the object as stream
    Files.copy(data, path, StandardCopyOption.REPLACE_EXISTING); // write the stream to local file path
}
    

Generate Object Parts for Download

In this SDK method we will download a portion of the object that falls under the required start and end range of bytes.

Parameters Used

• PartSize: It is the size of each part in Mb
• key: Will hold the name of the object

Ensure the following packages are imported

    

        
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         import java.nio.file.StandardOpenOption;
import java.nio.file.Files;
import com.zc.component.stratus.beans.ZCStratusGetObject;
import java.nio.file.Path;
import java.io.*;
    

    

        
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         Path path = Path.of("file_path");
// get the list of part functions
List<ZCStratusGetObject> parts = transferManager.generatePartDownloaders("sam/out/sample.txt", 100L);
// create a file to store the downloaded stream.
Files.createFile(path);
int partNumber = 1;
// trigger the each function to download the object parts
for (ZCStratusGetObject part : parts) {
// get object part as stream
 InputStream inputStream = part.getPart();
  System.out.println("Part "+ partNumber++ + " Downloaded");
// write the stream data to local machine
  Files.write(path, inputStream.readAllBytes(), StandardOpenOption.APPEND);
}
    

Generate Presigned URL to Download an Object

Presigned URLs are secure URLs that authenticated users can share to their non-authenticated users. This URL will provide non-authenticated users with temporary authorization to access objects. The Bucket reference used in the below code snippet is the component instance.

Parameters Used

Ensure the following packages are imported

    

        
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         import com.zc.component.stratus.enums.URL_ACTION;
import org.json.simple.JSONObject;
    

    

        
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         JSONObject res = bucket.generatePreSignedUrl("sam/out/sample.txt",URL_ACTION.GET);
System.out.println(res.get("signature"));
    

Generate Presigned URL With Expiry and Active Time

Ensure the following packages are imported

    

        
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         import com.zc.component.stratus.enums.URL_ACTION;
import org.json.simple.JSONObject;
    

    

        
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         JSONObject res = bucket.generatePreSignedUrl("object_name",URL_ACTION.GET, "expiry_in","active_from");
System.out.println(res.get("signature"));

    

Example Response for Generating a Presigned URL for Download

    

        
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         {
  signature: 'https://sadi-development.zoho stratus.com/_signed/text.txt?organizationId=96862383&stsCredential=96858154-96862383&stsDate=1747896279887&stsExpiresAfter=300&stsSignedHeaders=host&stsSignature=3YBUX1HFSxNQzQJjFrln82AyJsEEuC5T9dsZwWxGyEE'
}

    

Example Snippet Illustrating Usage of Presigned URL to Upload an Object

    

        
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import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Download {
    public static void main(String[] args) throws IOException {
        // Create an OkHttpClient instance to handle the HTTP request
        OkHttpClient client = new OkHttpClient();

        // Build the GET request with the pre-signed URL
        Request request1 = new Request.Builder()
                .url("https://sadi-development.zohostratus.com/_signed/sam.txt?organizationId=96862383&stsCredential=96858154-96862383&stsDate=1747905744487&stsExpiresAfter=300&stsSignedHeaders=host&stsSignature=pCjV9xckDOqBCueE_gBeMbp12StddTghBK_8HUwU5k0") // Replace with your actual URL
                .build();

        // Execute the request and handle the response
        try (Response response1 = client.newCall(request1).execute()) {
            // Check if the response was successful
            if (!response1.isSuccessful()) {
                throw new IOException("Unexpected code " + response1);
            }

            // Get the response body as an InputStream
            ResponseBody body = response1.body();
            if (body != null) {
                // Create a stream to write the file to disk
                try (InputStream in = body.byteStream();
                     OutputStream out = new FileOutputStream("file_path")) { // Replace file_path with the actual path

                    // Read the response data in chunks and write to the file
                    byte[] buffer = new byte[8192];
                    int len;
                    while ((len = in.read(buffer)) != -1) {
                        out.write(buffer, 0, len);
                    }

                    // Print confirmation after successful download
                    System.out.println("Download complete.");
                }
            }
        } catch (IOException e) {
            // Print stack trace if an error occurs during the download
            e.printStackTrace();
        }
    }
}