The Conflux Java SDK allows any Java client to interact with a local or remote Conflux node based on JSON-RPC 2.0 protocol. With Conflux Java SDK, user can easily manage accounts, send transactions, deploy smart contracts and query blockchain information.
Use AccountManager to manage accounts at local machine.
- Create/Import/Update/Delete an account.
- List all accounts.
- Unlock/Lock an account.
- Sign a transaction.
package conflux.sdk.examples;
import conflux.web3j.AccountManager;
public class App {
public static void main(String[] args) throws Exception {
String privateKey = "0xxxxxx";
// Initialize a accountManager
AccountManager am = new AccountManager();
// import private key
am.imports(privateKey, "123456");
// import a keystore file
am.imports("keystore file path", "old password", "new password");
// then you can use am to signTransaction or signMessage
}
}- Sign a transaction with unlocked account:
AccountManager.signTransaction(RawTransaction tx, String address)- Sign a transaction with passphrase for locked account:
AccountManager.signTransaction(RawTransaction tx, String address, String password)Use Cfx interface to query Conflux blockchain information, such as block, epoch, transaction, receipt. Following is an example to query the current epoch number:
package conflux.sdk.examples;
import java.math.BigInteger;
import conflux.web3j.Cfx;
public class App {
public static void main(String[] args) throws Exception {
Cfx cfx = Cfx.create("http://mainnet-jsonrpc.conflux-chain.org:12537", 3, 1000);
BigInteger epoch = cfx.getEpochNumber().sendAndGet();
System.out.println("Current epoch: " + epoch);
}
}Cfx interface provides a factory method to create an instance, and allow client to enable auto-retry mechanism in case of temporary IO errors.
To send a transaction, first you need to build a transaction and sign the transaction at local machine, then send the signed transaction to local or remote Conflux node.
BigInteger value = new BigInteger("1000", 16);
TransactionBuilder txBuilder = new TransactionBuilder("0x-the-sender-address");
txBuilder.withChainId(1);
txBuilder.withTo("0x13d2bA4eD43542e7c54fbB6c5fCCb9f269C1f94C");
txBuilder.withValue(value);
RawTransaction rawTx = txBuilder.build(cfx);
// get account from accountManager, `account.send` will sign the tx and send it to blockchain
SendTransactionResult result = account.send(rawTx);
System.out.println(result.getTxHash());
// or you can manually sign and send
String hexEncodedTx = account.sign(rawTx);
String txHash = cfx.sendRawTransaction(hexEncodedTx).sendAndGet();If you just want to transfer some CFX, there is a simpler method account.transfer
Option opt = new Option();
opt.withChainId(1);
account.waitForNonceUpdated();
String result = account.transfer(opt, "0x13d2bA4eD43542e7c54fbB6c5fCCb9f269C1f94C", value);There are three types of address in Conflux:
- User address: starts with
0x1. - Contract address: starts with
0x8. - Internal contract: starts with
0x0.
Conflux Java SDK provides some utilities to validate or format address, please refer to Address and AddressType for more details.
The underlying library Web3j also provides API to convert address to a checksumed format.
Keys.toChecksumAddress(String address)The conflux-rust fullnode support PubSub through websocket, the default port is 12535, you need open it manually.
Now the SDK provide three methods subscribeNewHeads, subscribeLogs, subscribeEpochs you can use to sub respect events.
// initiate a WebSocketService and connect, then use it to create a Cfx
WebSocketService wsService = new WebSocketService("ws://localhost:12535/", false);
wsService.connect();
Cfx cfx = Cfx.create(wsService);
// Invoke cfx method
BigInteger epoch = cfx.getEpochNumber().sendAndGet();
System.out.println("Current epoch: " + epoch);
// PubSub Subscribe to incoming events and process incoming events
final Flowable<NewHeadsNotification> events = cfx.subscribeNewHeads();
final Disposable disposable = events.subscribe(event -> {
// You can get the detail through getters
System.out.println(event.getParams().getResult());
});
// close
disposable.dispose();To simple call a contract method you can use the ContractCall class
package conflux.sdk.examples;
import conflux.web3j.contract.ContractCall;
import org.web3j.abi.datatypes.Address;
import conflux.web3j.contract.abi.DecodeUtil;
import org.web3j.abi.datatypes.generated.Uint256;
public class App {
public static void main(String[] args) throws Exception {
ContractCall contract = new ContractCall(cfx, "0x824df34537b198d9955c01c4e5a2a68733707b4f");
// passing method name and parameter to `contract.call`
// note: parameters should use web3j.abi.datatypes type
String amount = contract.call("balanceOf", new Address("0x1386B4185A223EF49592233b69291bbe5a80C527")).sendAndGet();
BigInteger balance = DecodeUtil.decode(amount, Uint256.class);
System.out.print("account balance: ");
System.out.println(balance);
}
}To update a contract's state you need to send a transaction to contract with data info, java-conflux-sdk have some method can do this for you.
For example:
package conflux.sdk.examples;
import conflux.web3j.Account;
import conflux.web3j.Account.Option;
import org.web3j.abi.datatypes.Address;
import org.web3j.abi.datatypes.generated.Uint256;
public class App {
public static void main(String[] args) throws Exception {
String privateKey = "0xxxxxx";
String contractAddress = "0xxxxx";
String recipient = "0xxxx";
BigInteger amount = 100;
// create account, then call contract's method
Account account = Account.create(cfx, privateKey);
Option opt = new Option();
// build transaction option info: nonce, gas, gasPrice and etc
String txHash = account.call(option, contractAddress, "transfer", new Address(recipient), new Uint256(amount));
System.out.println("tx hash: " + txHash);
}
}Conflux Java SDK also provides some helpful tools:
Account: used for a single account to send multiple transactions and managenonceautomatically.CfxUnit: provides utilities for unit conversion.ContractCall: query contract data without ABI file.DecodeUtilandTupleDecoder: provides utilities for ABI decode.Recall: diagnose failed transactions.
Conflux network's vm is compatible with evm, and a lot web3j functionality can directly used on Conflux network,
For example Sign, encode and so on.
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