Skip to main content

Web3j extension for kaia

Requirements​

Setting Java​

Install Web3j kaia extension​

To add the Gradle Library to your project:


repositories {
mavenCentral()
}
dependencies {
implementation "foundation.klaytn:web3j-ext:v0.9.3"
implementation "foundation.klaytn:web3rpc-java:v0.9.0"
implementation "org.web3j:core:4.9.8"
}

Usage​

See example.

Quickstart​

For basic web3j usage, you can learn through Web3j tutorial .

Send Fee Delegated Transaction on Baobab Test network​

If you want to know more about the concept of fee delegated transaction supported by kaia network, please refer to kaiadocs.

Check FeeDelegatedValueTransferExample.java file in web3j-ext examples.


package org.web3j.example;
import java.io.IOException;
import java.math.BigInteger;
import org.web3j.crypto.KlayCredentials;
import org.web3j.crypto.KlayRawTransaction;
import org.web3j.crypto.KlayTransactionEncoder;
import org.web3j.crypto.transaction.type.TxType;
import org.web3j.crypto.transaction.type.TxTypeValueTransfer;
import org.web3j.crypto.transaction.type.TxType.Type;
import org.web3j.protocol.core.DefaultBlockParameterName;
import org.web3j.protocol.core.methods.response.EthChainId;
import org.web3j.protocol.core.methods.response.EthSendTransaction;
import org.web3j.protocol.http.HttpService;
import org.web3j.protocol.kaia.Web3j;
import org.web3j.utils.Numeric;
import org.web3j.protocol.kaia.core.method.response.TransactionReceipt;
public class FeeDelegatedValueTransferExample implements keySample {
public static void run() throws Exception {
Web3j web3j = Web3j.build(new HttpService(keySample.BAOBAB_URL));
KlayCredentials credentials = KlayCredentials.create(keySample.LEGACY_KEY_privkey);
KlayCredentials credentials_feepayer = KlayCredentials.create(keySample.LEGACY_KEY_FEEPAYER_privkey);
BigInteger GAS_PRICE = BigInteger.valueOf(50000000000L);
BigInteger GAS_LIMIT = BigInteger.valueOf(6721950);
String from = credentials.getAddress();
EthChainId EthchainId = web3j.ethChainId().send();
long chainId = EthchainId.getChainId().longValue();
String to = "0x000000000000000000000000000000000000dead";
BigInteger nonce = web3j.ethGetTransactionCount(from, DefaultBlockParameterName.LATEST).send()
.getTransactionCount();
BigInteger value = BigInteger.valueOf(100);
TxType.Type type = Type.FEE_DELEGATED_VALUE_TRANSFER;
KlayRawTransaction raw = KlayRawTransaction.createTransaction(
type,
nonce,
GAS_PRICE,
GAS_LIMIT,
to,
value,
from);
// Sign as sender
byte[] signedMessage = KlayTransactionEncoder.signMessage(raw, chainId, credentials);
// Sign same message as Fee payer
signedMessage = KlayTransactionEncoder.signMessageAsFeePayer(raw, chainId, credentials_feepayer);
String hexValue = Numeric.toHexString(signedMessage);
EthSendTransaction transactionResponse = web3j.ethSendRawTransaction(hexValue).send();
System.out.println("TxHash : \n " + transactionResponse.getResult());
String txHash = transactionResponse.getResult();
int DEFAULT_POLLING_ATTEMPTS_PER_TX_HASH = 40;
int DEFAULT_BLOCK_TIME = 1 * 1000;
long DEFAULT_POLLING_FREQUENCY = DEFAULT_BLOCK_TIME;
TransactionReceiptProcessor transactionReceiptProcessor = new PollingTransactionReceiptProcessor(web3j,
DEFAULT_POLLING_FREQUENCY, DEFAULT_POLLING_ATTEMPTS_PER_TX_HASH);
org.web3j.protocol.core.methods.response.TransactionReceipt ethReceipt = transactionReceiptProcessor
.waitForTransactionReceipt(txHash);
System.out.println("Receipt from eth_getTransactionReceipt : \n" + ethReceipt);
TransactionReceipt receipt = web3j.klayGetTransactionReceipt(txHash).send().getResult();
System.out.println("Receipt from klay_getTransactionReceipt : \n" + receipt);
web3j.shutdown();
TxTypeFeeDelegatedValueTransfer rawTransaction = TxTypeFeeDelegatedValueTransfer
.decodeFromRawTransaction(hexValue);
System.out.println("TxType : " + rawTransaction.getKlayType());
}
}

Run examples


import org.web3j.example.FeeDelegatedValueTransferExample;
public class quickstart {
public static void main(String[] args) throws Exception {
FeeDelegatedValueTransferExample.run();
}
}