以太坊常见问题和错误 / Web3j error:Intrinsic gas too low

我是一个以太坊区块链ethereum blockchain开发新手，我一直尝试执行智能合约使用MetaMask和Remix在Chrome浏览器上。

我现在正在尝试使用web3j开发并通过Java部署相同的以太坊智能合约。

但是当我尝试执行我的智能合约时，得到以下错误：error Intrinsic gas too low

Exception in thread "main" java.util.concurrent.ExecutionException: java.lang.RuntimeException: Error processing transaction request: Intrinsic gas too low
    at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
    at java.util.concurrent.CompletableFuture.get(Unknown Source)
    at com.solartis.bc.Sample.main(Sample.java:44)
Caused by: java.lang.RuntimeException: Error processing transaction request: Intrinsic gas too low
    at org.web3j.tx.ManagedTransaction.send(ManagedTransaction.java:43)
    at org.web3j.tx.Contract.lambda$deployAsync$24(Contract.java:288)...

我已经通过几个方法来增加gas的值，但是不管我支付多大的值，我仍然会得到同样的错误。

有没有其他人面临同样的问题，我不知道问题在哪儿。下面附上更多细节：

ContractRunner.java

package com.solartis.bc;

public class ContractRunner {

    public static void main(String args[]) throws InterruptedException, ExecutionException, IOException, CipherException, TransactionTimeoutException {
        Web3j web3 = Web3j.build(new HttpService("http://xxxxxxx.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("Mxxxxxxxxe", "C:\\Users\\adheep_m\\AppData\\Roaming\\Ethereum\\keystore\\UTC--2017-07-07T13-52-18.006069200Z--3b0d3fa08f0e0b3da8fe1f8ac0e05861bfdada25");
        System.out.println(credentials.getAddress());

        BigInteger GAS = new BigInteger("30000000");
        BigInteger GAS_PRICE = new BigInteger("20");
        BigInteger ETH = new BigInteger("1");
        //LeisureTravelPolicyHolder contract = LeisureTravelPolicyHolder.deploy(web3,credentials,GAS,GAS_PRICE,ETH,test,test,test,test,test,test,test,test,test).get();

        Token con = Token.deploy(web3,credentials,GAS,GAS_PRICE,ETH).get();
        System.out.println(con.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:

package com.solartis.bc;

import java.math.BigInteger;
import java.util.Arrays;
import java.util.Collections;
import java.util.concurrent.Future;
import org.web3j.abi.TypeReference;
import org.web3j.abi.datatypes.Address;
import org.web3j.abi.datatypes.Function;
import org.web3j.abi.datatypes.Type;
import org.web3j.abi.datatypes.generated.Uint256;
import org.web3j.crypto.Credentials;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.core.methods.response.TransactionReceipt;
import org.web3j.tx.Contract;
import org.web3j.tx.TransactionManager;

/**
 * Auto generated code.<br>
 * <strong>Do not modify!</strong><br>
 * Please use {@link org.web3j.codegen.SolidityFunctionWrapperGenerator} to update.
 *
 * <p>Generated with web3j version 2.2.1.
 */
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);
    }
}

问题原因及解决

问题出现在GAS_PRICE和GAS_LIMIT不合适。Web3j有默认的GAS_PRICE和GAS_LIMIT。以下是更新后的代码：

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

Contract.GAS_LIMIT和Contract.GAS_PRICE被启用了，因此，使用下面的常数org.web3j.tx.gas.DefaultGasProvider来代替:

    DefaultGasProvider.GAS_PRICE;
    DefaultGasProvider.GAS_LIMIT;