获取智能合约交易的解码输出

Question

我正在使用以下代码通过web3j执行智能合约的功能:

Credentials creds = getCredentialsFromPrivateKey("private-key");
RawTransactionManager manager = new RawTransactionManager(web3j, creds);
String contractAddress = "0x1278f8c858d799fe1010cfc0d1eeb56508243a4d";
BigInteger sum = new BigInteger("10000000000"); // amount you want to send
String data = encodeTransferData(sum);
BigInteger gasPrice = web3j.ethGasPrice().send().getGasPrice();
BigInteger gasLimit = BigInteger.valueOf(120000); // set gas limit here
EthSendTransaction transaction = manager.sendTransaction(gasPrice, gasLimit, contractAddress, data, null);
System.out.println(transaction.getTransactionHash());

它执行得很好，函数运行了，但是我不知道如何读取合约给出的输出，我如何读取输出?

Answer 1

这将返回函数调用的十六进制值

private static List<Type> executeCall(Function function) throws IOException {
String encodedFunction = FunctionEncoder.encode(function);
org.web3j.protocol.core.methods.response.EthCall ethCall = web3j.ethCall(
Transaction.createEthCallTransaction(
"0x753ebAf6F6D5C2e3E6D469DEc5694Cd3Aa1A0c21", "0x47480bac30de77cd030b8a8dad2d6a2ecdb7f27a", encodedFunction),
DefaultBlockParameterName.LATEST)
.send();
String value = ethCall.getValue();
System.out.println(value);
System.out.println(FunctionReturnDecoder.decode(value, function.getOutputParameters()));
return FunctionReturnDecoder.decode(value, function.getOutputParameters());
}

Answer 2

以太坊交易哈希是交易的唯一id。有了这个事务哈希，你可以从网络上查询事务状态。

底层JSON-RPC调用称为eth_getTransactionReceipt。这是Web3.js文档。

如果你的智能合约发出事件，你也可以读取它们。