无法使用web3j(Java客户端)将智能合约部署到私有链上，错误提示信息是超时。

我用web3j与我在Azure中创建的私有链进行交互。我使用Remix和Metamask创建了以太坊智能合约，并且能够从Java中查看该智能合约。

但是，我无法从Java部署或创建合同。我遵循了web3j的命令但是抛出了这个：

1.错误提示：Transaction receipt was not generated after 600 seconds for transaction

2.报错原因是：org.web3j.protocol.exceptions.TransactionTimeoutException

我的代码如下：

ContractRunner.java

public static void main(String args[]) throws InterruptedException, ExecutionException, IOException, CipherException, TransactionTimeoutException {
        Web3j web3 = Web3j.build(new HttpService("http://xxxxxxxxx.westus.cloudapp.azure.com:8545/"));  // defaults to http://localhost:8545/
        Web3ClientVersion web3ClientVersion = web3.web3ClientVersion().sendAsync().get();
        String clientVersion = web3ClientVersion.getWeb3ClientVersion();
        System.out.println(clientVersion);
        Credentials credentials = WalletUtils.loadCredentials("MyPassword", "C:\\Users\\adheep_m\\AppData\\Roaming\\Ethereum\\keystore\\UTC--2017-07-07T13-52-18.006069200Z--3b0d3fa08f0e0b3da8fe1f8ac0e05861bfdada25");
        System.out.println(credentials.getAddress());

        Token contract = Token.deploy(web3,credentials,BigInteger.valueOf(3000000),BigInteger.valueOf(3000000),BigInteger.valueOf(0)).get();
        System.out.println(contract.getContractAddress());
    }

Token.sol

pragma solidity ^0.4.0;

contract Token {
mapping (address => uint) public balances;

function Token() {
    balances[msg.sender] = 1000000;
}

function transfer(address _to, uint _amount) {
    if (balances[msg.sender] < _amount) {
        throw;
    }

    balances[msg.sender] -= _amount;
    balances[_to] += _amount;
}

Token.java (Generated from Web3j)

public final class Token extends Contract {
    private static final String BINARY = "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";

    private Token(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
        super(BINARY, contractAddress, web3j, credentials, gasPrice, gasLimit);
    }

    private Token(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
        super(BINARY, contractAddress, web3j, transactionManager, gasPrice, gasLimit);
    }

    public Future<Uint256> balances(Address param0) {
        Function function = new Function("balances", 
                Arrays.<Type>asList(param0), 
                Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));
        return executeCallSingleValueReturnAsync(function);
    }

    public Future<TransactionReceipt> transfer(Address _to, Uint256 _amount) {
        Function function = new Function("transfer", Arrays.<Type>asList(_to, _amount), Collections.<TypeReference<?>>emptyList());
        return executeTransactionAsync(function);
    }

    public static Future<Token> deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit, BigInteger initialWeiValue) {
        return deployAsync(Token.class, web3j, credentials, gasPrice, gasLimit, BINARY, "", initialWeiValue);
    }

    public static Future<Token> deploy(Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit, BigInteger initialWeiValue) {
        return deployAsync(Token.class, web3j, transactionManager, gasPrice, gasLimit, BINARY, "", initialWeiValue);
    }

    public static Token load(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
        return new Token(contractAddress, web3j, credentials, gasPrice, gasLimit);
    }

    public static Token load(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
        return new Token(contractAddress, web3j, transactionManager, gasPrice, gasLimit);
    }
}

我不确定代码有什么问题。

问题的解决

我知道代码出了什么问题。我调试了web3j的源代码，发现由于挖掘节点在40次重试后不接受交易，其休眠持续时间为15000，因此引发交易TransactionTimeoutException，并且不生成TransactionReceipt。从TransactionManager.java看下面的web3j代码：

Source of the Exception

private static final int SLEEP_DURATION = 15000;
private static final int ATTEMPTS = 40;

private TransactionReceipt getTransactionReceipt(
        String transactionHash, int sleepDuration, int attempts)
        throws IOException, InterruptedException, TransactionTimeoutException {

    Optional<TransactionReceipt> receiptOptional =
            sendTransactionReceiptRequest(transactionHash);
    for (int i = 0; i < attempts; i++) {
        if (!receiptOptional.isPresent()) {
            Thread.sleep(sleepDuration);
            receiptOptional = sendTransactionReceiptRequest(transactionHash);
        } else {
            return receiptOptional.get();
        }
    }

    throw new TransactionTimeoutException("Transaction receipt was not generated after " +
            ((sleepDuration * attempts) / 1000 +
                    " seconds for transaction: " + transactionHash));
}

真正的原因是

发现问题真正的原因是GAS_PRICE和GAS_LIMIT。由于价值低，矿工没有开采这个交易。

更新代码，从web3j的智能合约Contract类，使用默认的GAS_PRICE和GAS_LIMIT限制。参见下面更新的代码

BigInteger GAS = Contract.GAS_LIMIT;
    BigInteger GAS_PRICE = Contract.GAS_PRICE;

    Token contract = Token.deploy(web3,credentials,GAS_PRICE,GAS,ETHER);
    System.out.println("Deployed Contract at "+contract.getContractAddress());

OK，完事大吉。