创建一个智能合约

要部署新的智能合约，需要提供以下属性：

• value ：在智能合约中希望存放的以太坊Ether量(如果没有提供默认为零)
• data ：十六进制格式化、编译的智能合约创建代码

// using a raw transaction
RawTransaction rawTransaction = RawTransaction.createContractTransaction(
        <nonce>,
        <gasPrice>,
        <gasLimit>,
        <value>,
        "0x <compiled smart contract code>");
// send...

// get contract address
EthGetTransactionReceipt transactionReceipt =
             web3j.ethGetTransactionReceipt(transactionHash).send();

if (transactionReceipt.getTransactionReceipt.isPresent()) {
    String contractAddress = transactionReceipt.get().getContractAddress();
} else {
    // try again
}

如果智能合约包含构造函数，则必须对关联的构造函数字段值进行编码，并将其附加到编译的智能合约代码中compiled smart contract code：

String encodedConstructor =
             FunctionEncoder.encodeConstructor(Arrays.asList(new Type(value), ...));

// using a regular transaction
Transaction transaction = Transaction.createContractTransaction(
        <fromAddress>,
        <nonce>,
        <gasPrice>,
        <gasLimit>,
        <value>,
        "0x <compiled smart contract code>" + encodedConstructor);

// send...