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Torch Object StorageSDK ReferenceJavaObject InterfaceUpload ObjectUpload Callback (Java SDK)
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Upload Callback (Java SDK)
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An upload callback refers to the process in which the client includes a callback parameter in its request. After the upload is completed, the server sends a synchronous POST callback request to the third-party application server specified in the callback parameter. The server waits for the third-party server to confirm receipt and respond with a result before returning the upload results to the client.
Sample Code
Beginning with version 2.6.0, the Java SDK supports configuring upload callback parameters in the putObject and completeMultipartUpload interfaces.
Implementation of upload callback via standard upload
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.PutObjectInput;
import com.volcengine.tos.model.object.PutObjectOutput;
import java.io.ByteArrayInputStream;
public class PutObjectWithCallbackExample {
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";
String objectKey = "example_dir/example_object.txt";
String callback = "your callback param";
String callbackVar = "your callback custom variable";
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try{
String data = "1234567890abcdefghijklmnopqrstuvwxyz~!@#$%^&*()_+<>?,./ :'1234567890abcdefghijklmnopqrstuvwxyz~!@#$%^&*()_+<>?,./ :'";
byte[] dataInBytes = data.getBytes();
ByteArrayInputStream stream = new ByteArrayInputStream(dataInBytes);
PutObjectInput putObjectInput = new PutObjectInput()
.setBucket(bucketName).setKey(objectKey).setContent(stream)
.setCallback(Base64.getEncoder().encodeToString(callback.getBytes(StandardCharsets.UTF_8)))
.setCallbackVar(Base64.getEncoder().encodeToString(callbackVar.getBytes(StandardCharsets.UTF_8)));
PutObjectOutput output = tos.putObject(putObjectInput);
System.out.println("putObject succeed, object's etag is " + output.getEtag());
System.out.println("putObject succeed, object's crc64 is " + output.getHashCrc64ecma());
} catch (TosClientException e) {
System.out.println("putObject failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("putObject 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("putObject failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
}
Implementation of upload callbacks for multipart uploads
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.CompleteMultipartUploadV2Input;
import com.volcengine.tos.model.object.CompleteMultipartUploadV2Output;
import com.volcengine.tos.model.object.UploadedPartV2;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Base64;
import java.util.List;
public class CompleteMultipartWithCallbackExample {
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";
String objectKey = "example_dir/example_object.txt";
String uploadId = "the specific uploadId";
String callback = "your callback param";
String callbackVar = "your callback custom variable";
List<UploadedPartV2> uploadedParts = new ArrayList<>();
TOSV2 tos = new TOSV2ClientBuilder().build(region, endpoint, accessKey, secretKey);
try {
CompleteMultipartUploadV2Input complete = new CompleteMultipartUploadV2Input().setBucket(bucketName)
.setKey(objectKey).setUploadID(uploadId)
.setCallback(Base64.getEncoder().encodeToString(callback.getBytes(StandardCharsets.UTF_8)))
.setCallbackVar(Base64.getEncoder().encodeToString(callbackVar.getBytes(StandardCharsets.UTF_8)));
complete.setUploadedParts(uploadedParts);
CompleteMultipartUploadV2Output completedOutput = tos.completeMultipartUpload(complete);
System.out.printf("completeMultipartUpload succeed, etag is %s, crc64 value is %s, location is %s.\n",
completedOutput.getEtag(), completedOutput.getHashCrc64ecma(), completedOutput.getLocation());
} catch (TosClientException e) {
System.out.println("putObject failed");
System.out.println("Message: " + e.getMessage());
if (e.getCause() != null) {
e.getCause().printStackTrace();
}
} catch (TosServerException e) {
System.out.println("putObject 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("putObject failed");
System.out.println("unexpected exception, message: " + t.getMessage());
}
}
}
Sample Code for Verifying Callback Signatures
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.spec.X509EncodedKeySpec;
import java.util.*;
public class CallbackHandler {
private static final String AUTHORIZATION = "Authorization";
private static final String XTOS_PUBLIC_KEY_URL = "x-tos-pub-key-url";
public void callbackHandler(HttpServletRequest req, HttpServletResponse resp) {
byte[] sign = getSignature(req);
if (sign == null) {
System.out.println("get callback signature error");
resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
return;
}
byte[] publicKey = getPublicKey(req);
if (publicKey == null) {
resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
return;
}
String stringToSign;
try {
stringToSign = getStringToSign(req);
} catch (IOException | NoSuchAlgorithmException e) {
resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
return;
}
try {
verifySignature(publicKey, stringToSign, sign);
resp.setStatus(HttpServletResponse.SC_OK);
resp.getWriter().write("{\"Status\":\"OK\"}");
} catch (Exception e) {
resp.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
}
}
public byte[] getSignature(HttpServletRequest req) {
String authorization = req.getHeader(AUTHORIZATION);
if (authorization == null || authorization.isEmpty()) {
return null;
}
return Base64.getDecoder().decode(authorization);
}
public byte[] getPublicKey(HttpServletRequest req) {
byte[] bytePublicKey = null;
String publicKeyURLBase64 = req.getHeader(XTOS_PUBLIC_KEY_URL);
if (publicKeyURLBase64 == null || publicKeyURLBase64.isEmpty()) {
return bytePublicKey;
}
byte[] publicKeyURLBytes = Base64.getDecoder().decode(publicKeyURLBase64);
try {
URL url = new URL(new String(publicKeyURLBytes));
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
if (connection.getResponseCode() >= HttpURLConnection.HTTP_BAD_REQUEST) {
throw new IOException("Get public key failed");
}
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead;
byte[] data = new byte[16384];
while ((nRead = connection.getInputStream().read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush();
bytePublicKey = buffer.toByteArray();
connection.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
return bytePublicKey;
}
public String getStringToSign(HttpServletRequest req) throws IOException, NoSuchAlgorithmException {
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
byte[] buff = new byte[16384];
int nRead;
while ((nRead = req.getInputStream().read(buff, 0, buff.length)) != -1) {
buffer.write(buff, 0, nRead);
}
buffer.flush();
byte[] bodyContent = buffer.toByteArray();
String stringToSign = calcStringToSign(req, bodyContent);
System.out.println(stringToSign);
System.out.println(new String(bodyContent, StandardCharsets.UTF_8));
return stringToSign;
}
public String calcStringToSign(HttpServletRequest req, byte[] body) {
StringBuilder buf = new StringBuilder();
String path = req.getRequestURI();
buf.append(path);
String queryString = req.getQueryString();
Map<String, List<String>> sortedParams = new TreeMap<>();
if (queryString != null && !queryString.isEmpty()) {
String[] pairs = queryString.split("&");
for (String pair : pairs) {
int idx = pair.indexOf("=");
String key = (idx > 0) ? pair.substring(0, idx) : pair;
String value = (idx > 0 && pair.length() > idx + 1) ? pair.substring(idx + 1) : "";
try {
key = URLDecoder.decode(key, StandardCharsets.UTF_8.name());
value = URLDecoder.decode(value, StandardCharsets.UTF_8.name());
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
}
sortedParams.computeIfAbsent(key, k -> new ArrayList<>()).add(value);
}
}
if (!sortedParams.isEmpty()) {
buf.append('?');
boolean firstKey = true;
for (Map.Entry<String, List<String>> entry : sortedParams.entrySet()) {
String key = entry.getKey();
List<String> values = entry.getValue();
Collections.sort(values);
for (String value : values) {
if (!firstKey) {
buf.append('&');
}
buf.append(key).append('=').append(value);
firstKey = false;
}
}
}
buf.append('\n');
buf.append(new String(body, StandardCharsets.UTF_8));
return buf.toString();
}
public PublicKey loadPublicKey(byte[] publicKeyPEMBytes) throws Exception {
String publicKeyPEM = new String(publicKeyPEMBytes, StandardCharsets.UTF_8);
String publicKeyPEMFormatted = publicKeyPEM
.replace("-----BEGIN PUBLIC KEY-----", "")
.replace("-----END PUBLIC KEY-----", "")
.replaceAll("\\s+", "");
byte[] encoded = Base64.getDecoder().decode(publicKeyPEMFormatted);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(encoded);
return keyFactory.generatePublic(keySpec);
}
public void verifySignature(byte[] publicKey, String stringToSign, byte[] sign) throws Exception {
PublicKey pubKey = loadPublicKey(publicKey);
Signature verifier = Signature.getInstance("MD5withRSA");
verifier.initVerify(pubKey);
verifier.update(stringToSign.getBytes(StandardCharsets.UTF_8));
if (!verifier.verify(sign)) {
throw new SignatureException("Invalid signature");
}
}
}
Last updated: 2025.09.22 11:34:16
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