如何使用web3j java对erc20令牌事务进行签名

Web3j web3 = Web3j.build(new HttpService("https://mainnet.infura.io/v3/your-infura-project-id"));

String contractAddress = "0x1234567890abcdef..."; // 替换为ERC20令牌的合约地址
String abi = "[{\"constant\":true,\"inputs\":[{\"name\":\"\",\"type\":\"address\"}],\"name\":\"balanceOf\",\"outputs\":[{\"name\":\"\",\"type\":\"uint256\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"}]"; // 替换为ERC20合约的ABI
Contract contract = Contract.load(abi, contractAddress, web3, credentials);

String privateKey = "your-private-key"; // 替换为私钥
Credentials credentials = Credentials.create(privateKey);

String toAddress = "0xabcdef1234567890..."; // 替换为接收ERC20令牌的地址
BigInteger value = BigInteger.valueOf(100); // 替换为转账的数量
BigInteger gasPrice = web3.ethGasPrice().send().getGasPrice();

RawTransaction rawTransaction = RawTransaction.createTransaction(
        NonceUtils.getNonce(web3, credentials.getAddress()),
        gasPrice,
        BigInteger.valueOf(21000), // 使用21000作为gas limit
        toAddress,
        value,
        "0x"
);

byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
String hexValue = Numeric.toHexString(signedMessage);

EthSendTransaction ethSendTransaction = web3.ethSendRawTransaction(hexValue).send();
String transactionHash = ethSendTransaction.getTransactionHash();