以下是使用的代码：

pragma solidity ^0.4.0;

contract Contract {    
    uint price;

    constructor(uint _price) public {
        price = _price;
    }

    function getPrice() public constant returns (uint) {
        return price;
    }
}

EthBlock.Block block = web3j.ethGetBlockByNumber(DefaultBlockParameterName.LATEST, true).send().getBlock();
Transaction transaction = web3j.ethGetTransactionByBlockHashAndIndex(block.getHash(), BigInteger.ZERO).send().getTransaction().get();
String hash = transaction.getHash();

Function function = new Function(DataExchangeOfferContract.FUNC_GETPRICE, Collections.emptyList(), Collections.singletonList(new TypeReference<Uint256>() {}));
String functionEncoder = FunctionEncoder.encode(function);

Transaction transaction = Transaction.createEthCallTransaction(address, functionEncoder, null);
EthCall response = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).send();
List<Type> types = FunctionReturnDecoder.decode(response.getValue(), function.getOutputParameters());
BigInteger price = (BigInteger) types.get(0).getValue();