简介
本文主要内容为区块链钱包移动端(Android)开发,介绍比特币钱包和以太坊钱包的开发过程,包含钱包的主要功能:
创建钱包,钱包余额,导出钱包,钱包转账等。Demo地址
区块链钱包
在日常生活中,大家都会买个钱包用于存放政府机构发行的纸币,那么什么是数字资产世界的钱包呢?
比特币钱包
以太坊钱包:Mist、Parity、MyEhterWallet、ImToken、MetaTask、Ledger(硬件钱包)
- 助记词等价于私钥
- Keystore + 密码 等价于私钥
EOS钱包
NEO钱包
量子钱包
-
On-chain
给一个钱包地址发送数字货币, 这笔交易在全网广播、被确认、被打包进区块。这是发生在链上的,被称为on-chain交易。on-chain钱包需要自己保管私钥。
-
Off-chain
相对于on-chain交易是off-chain交易。通常,通过交易所进行的交易是off-chain的,本人并没有私钥。私钥在交易所,由交易所托管。所以交易所的钱包也是中心化的钱包。
-
冷钱包
冷即离线、断网,也就是说私钥存储的位置不能被网络所访问。例如纸钱包、脑钱包、硬件钱包等等。
-
热钱包
热即联网,也就是私钥存储在能被网络访问的位置。 例如存放在交易所的、在线钱包网站、手机App钱包都属于热钱包。通常而言,冷钱包更加安全,热钱包使用更加方便。
非确定性钱包
钱包随机生成确定性钱包(HD Wallets)
同一个种子,能够派生一样的密钥对集合-
全节点钱包
除了保存私钥外,全节点钱包还有保存了所有区块的数据,最为著名的是bitcoin-core。
-
轻钱包
它不必保存所有区块的数据,只保存跟自己相关的数据。基本可以实现去中心化。
-
中心化钱包
在交易所中的钱包,以及类似 OKLink 提供的保险柜服务。
比特币钱包
https://bitcoin.org/en/developer-guide#wallets
- 比特币钱包的组成
- 比特币钱包地址的创建过程
- BIP32
- BIP39
- BIP43
- BIP44
- BitcoinJ创建钱包
- Bitcoin钱包收款和转账
比特币钱包组成
比特币钱包分为两部分:钱包程序和钱包文件
钱包文件
保存私钥和转账记录
Wallet containing 0.01 BTC (spendable: 0.01 BTC) in:
0 pending transactions
1 unspent transactions
0 spent transactions
0 dead transactions
Last seen best block: 1384907 (2018-08-22T03:38:42Z): 0000000000000030fe01a48a7cd6b0c52909a7d019084d195ae3ebd2889c82ec
Keys:
Earliest creation time: 2018-08-20T07:51:29Z
Seed birthday: 1534751489 [2018-08-20T07:51:29Z]
Key to watch: tpubD92y4mcSrbcSxANfCgiWx7h7sGquSF4ogNPcUxC2GECSwgWBMNPMo2C8nxez2ngvSS4UfaGhSunemWoqZ6aAAzLb4WLsmQxDirfFgE9tG5J
addr:mq5gdvJDuDEmNKFPbgMn8pGm3pyJvkSsHv hash160:68e9c9e06890527cd0f0b59d83333502ac127bef (M/0H/0/0)
>>> UNSPENT:
0.01 BTC total value (sends 0.00 BTC and receives 0.01 BTC)
confidence: Seen by 7 peers (most recently: 2018-08-22T03:33:33Z). Appeared in best chain at height 1384907, depth 1. Source: NETWORK
a82c35c2133bd357bfa462f82d75b28787afcdcd20c8b89cd2b78f48138d6e9f
updated: 2018-08-22T03:31:53Z
in PUSHDATA(71)[304402205d3e0974b4604b92e09f83950b183100bd47243c9cb548f2213a9ca26e83bdd3022018278c7ce9b65982e6c67ba9acf8e6e3898f1dad80702bb1e32c4a0b61195e0f01] PUSHDATA(33)[02f8769ecddd821cc9b75c554978b4a674df28c098e640fd0188b88bf019bc31fa]
outpoint:8294b8dcf6513ab13321d4dd1642bf1c19600a313bf1ebe8511521dcd4dd0277:0
out DUP HASH160 PUSHDATA(20)[8843beff2291c5a00aa00fbd8a541f800c83b86d] EQUALVERIFY CHECKSIG 1.1899548 BTC
out DUP HASH160 PUSHDATA(20)[68e9c9e06890527cd0f0b59d83333502ac127bef] EQUALVERIFY CHECKSIG 0.01 BTC
prps UNKNOWN
## ##
钱包程序
钱包程序,创建公钥来接受satoshi,使用私钥来使用satoshi。钱包程序可以拆分出3个独立的模块:公钥分发模块、签名模块、网络模块
比特币单位:
1比特币(Bitcoins,BTC)
0.01比特分(Bitcent,cBTC)
0.001毫比特(Milli-Bitcoins,mBTC)
0.000001微比特(Micro-Bitcoins,μBTC或uBTC)
0.00000001聪(satoshi)(基本单位)
1 bitcoin (BTC) = 1000 millibitcoins (mBTC) = 1 million microbitcoins (uBTC) = 100 million Satoshi
根据三个模块的组合,可以分为全服务钱包、只签名钱包(离线钱包和硬件钱包)、只分发钱包。
BIP协议
Bitcoin Improvement Proposals
BIP32
BIP32:定义了层级确定性钱包(hierarchical deterministic wallets),是一个系统可以从单一个 seed 产生一树状结构储存多组 keypairs(私钥和公钥)。好处是可以方便的备份、转移到其他相容装置(因为都只需要 seed),以及分层的权限控制等。
作用:
1、备份更容易。按照比特币的原则,尽量不要使用同一个地址,一个地址只使用一次,这样会导致频繁备份钱包。HD钱包只需要在创建时保存主密钥,通过主密钥可以派生出所有的子密钥。
2、私钥离线更安全。主私钥离线存储,主公钥在线使用,通过主公钥可以派生出所有的子公钥。例如:给每个商品提供一个收款地址。
3、利于管理,权限控制。树状结构类似于公司的组织架构,可以给各个部门指定一个密钥分支。
4、记账。只使用公钥即可记账。
BIP39
BIP39:将seed 用方便记忆和书写的单字表示。一般由 12 个单字组成,称为 mnemonic code(phrase),中文称为助记词或助记码。例如:
average green proud remember advance trick estate oblige trouble when cube person
Wordlists
工具
BIP43
BIP43
BIP43对BIP32树结构增加了子索引标识purpose的拓展m/purpose'/*
BIP32的索引:m/0'/*
BIP44的索引:m/44'/*。
BIP44
BIP44:基于BIP32和BIP43,赋予树状结构中的各层特殊的意义。让同一个 seed 可以支援多币种、多帐户等。各层定义如下:
m / purpose' / coin_type' / account' / change / address_index
- purporse': 固定值44', 代表是BIP44
- coin_type': 这个代表的是币种, 可以兼容很多种币, 比如BTC是0', ETH是60', 例如:btc一般是 m/44'/0'/0'/0, eth一般是 m/44'/60'/0'/0
- account':账号
- change': 0表示外部链(External Chain),用户接收比特币,1表示内部链(Internal Chain),用于接收找零
- address_index:钱包索引
钱包最佳实践
- 使用助记词(BIP39)
- 使用层级确定性钱包(HD Wallets)(BIP32)
- 使用多目的HD Wallets(BIP43)
- 使用多币种,多账号的HD Wallets (BIP44)
比特币钱包地址创建过程
1、生成128bit~256bit作为私钥
2、通过secp256k1椭圆曲线算法得到私钥对应的公钥
3、将公钥进行SHA-256,得到公钥Hash
4、将3的结果进行RIMEMD-160
5、将4中结果添加1个字节版本号
6、将5中结果进行两次SHA-256,取前4个字节作为checksum
7、将6中结果添加到5中结果的末尾
8、将7中结果进行Base58,结果为比特币地址
BitcoinJ创建钱包
Bitcoinj是比特币协议Java版本实现的库。
添加依赖:
dependencies {
implementation 'org.bitcoinj:bitcoinj-core:0.14.7'
implementation 'org.slf4j:slf4j-api:1.7.25'
implementation 'com.squareup.okhttp3:okhttp:3.10.0'
implementation 'com.squareup.okhttp3:logging-interceptor:3.10.0'
implementation 'com.google.zxing:core:3.3.3'//二维码
}
Android最大方法数的限制,60K
开启multiDexEnabled
android {
compileSdkVersion 28
defaultConfig {
multiDexEnabled true
}
}
dependencies {
implementation 'com.android.support:multidex:1.0.3'
}
创建新钱包
File walletFile = activity.getFileStreamPath("wallet-protobuf");
//创建钱包
wallet = new Wallet(Constants.NETWORK_PARAMETERS);
//创建WalletFiles,设置自动保存Wallet
WalletFiles walletFiles = wallet.autosaveToFile(walletFile, 3 * 1000, TimeUnit.MILLISECONDS, null);
//立即保存
walletFiles.saveNow();
钱包创建源码分析:
Wallet
KeyChainGroup
DeterministicKeyChain
-
DeterministicSeed
protected DeterministicKeyChain(DeterministicSeed seed, @Nullable KeyCrypter crypter) { this.seed = seed; basicKeyChain = new BasicKeyChain(crypter); if (!seed.isEncrypted()) { rootKey = HDKeyDerivation.createMasterPrivateKey(checkNotNull(seed.getSeedBytes())); rootKey.setCreationTimeSeconds(seed.getCreationTimeSeconds()); addToBasicChain(rootKey); hierarchy = new DeterministicHierarchy(rootKey); for (int i = 1; i <= getAccountPath().size(); i++) { addToBasicChain(hierarchy.get(getAccountPath().subList(0, i), false, true)); } initializeHierarchyUnencrypted(rootKey); } // Else... // We can't initialize ourselves with just an encrypted seed, so we expected deserialization code to do the // rest of the setup (loading the root key). }
获取钱包地址
Address address = wallet.currentAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS);
address.toString();
在获取地址的过程中会调用RIMEMD-160算法处理公钥hash:
//Utils.java
public static byte[] sha256hash160(byte[] input) {
byte[] sha256 = Sha256Hash.hash(input);
RIPEMD160Digest digest = new RIPEMD160Digest();
digest.update(sha256, 0, sha256.length);
byte[] out = new byte[20];
digest.doFinal(out, 0);
return out;
}
处理公钥hash后会进行Base58算法:
//VersionedChecksummedBytes.java
public final String toBase58() {
// A stringified buffer is:
// 1 byte version + data bytes + 4 bytes check code (a truncated hash)
byte[] addressBytes = new byte[1 + bytes.length + 4];
addressBytes[0] = (byte) version;
System.arraycopy(bytes, 0, addressBytes, 1, bytes.length);
byte[] checksum = Sha256Hash.hashTwice(addressBytes, 0, bytes.length + 1);
System.arraycopy(checksum, 0, addressBytes, bytes.length + 1, 4);
return Base58.encode(addressBytes);
}
从文件中加载钱包
//读取钱包文件
File walletFile = activity.getFileStreamPath("wallet-protobuf");
if (walletFile.exists()) {
InputStream inputStream = new FileInputStream(walletFile);
//反序列化
wallet = new WalletProtobufSerializer().readWallet(inputStream);
//设置自动保存
wallet.autosaveToFile(walletFile, 3 * 1000, TimeUnit.MILLISECONDS, null);
//清理钱包
wallet.cleanup();
}
创建地址二维码
String s = BitcoinURI.convertToBitcoinURI(address, null, null, null);
Bitmap bitmap = Qr.bitmap(s);
BitmapDrawable bitmapDrawable = new BitmapDrawable(getResources(), bitmap);
bitmapDrawable.setFilterBitmap(false);
mQrImageView.setImageDrawable(bitmapDrawable);
public static Bitmap bitmap(final String content) {
try {
final Hashtable hints = new Hashtable();
hints.put(EncodeHintType.MARGIN, 0);
hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
final BitMatrix result = QR_CODE_WRITER.encode(content, BarcodeFormat.QR_CODE, 0, 0, hints);
final int width = result.getWidth();
final int height = result.getHeight();
final byte[] pixels = new byte[width * height];
for (int y = 0; y < height; y++) {
final int offset = y * width;
for (int x = 0; x < width; x++) {
pixels[offset + x] = (byte) (result.get(x, y) ? -1 : 0);
}
}
final Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ALPHA_8);
bitmap.copyPixelsFromBuffer(ByteBuffer.wrap(pixels));
return bitmap;
} catch (final WriterException x) {
log.info("problem creating qr code", x);
return null;
}
}
Bitcoin钱包收款和转账
比特币钱包余额需要统计所有钱包地址对应的UTXO
Simplified Payment Verification (SPV):节点无需下载所有的区块数据,而只需要加载所有区块头数据(block header的大小为80B),即可验证这笔交易是否曾经被比特币网络认证过。
布隆过滤器(Bloom Filter):过滤掉那些不包含有目标地址的交易信息,这一步能避免掉大量不相关的数据下载。
创建区块链
//创建区块链文件
File blockChainFile = new File(getDir("blockstore", Context.MODE_PRIVATE), "blockchain");
//创建SPVBlockStore,管理区块数据
blockStore = new SPVBlockStore(Constants.NETWORK_PARAMETERS, blockChainFile);
//加载检查点
final InputStream checkpointsInputStream = getAssets().open("checkpoints-testnet.txt");
CheckpointManager.checkpoint(Constants.NETWORK_PARAMETERS, checkpointsInputStream,
blockStore, earliestKeyCreationTime);
//创建区块链对象
blockChain = new BlockChain(Constants.NETWORK_PARAMETERS, wallet, blockStore);
同步区块链
//添加网络权限:
private void startup() {
Log.d(TAG, "startup: ");
peerGroup = new PeerGroup(Constants.NETWORK_PARAMETERS, blockChain);
peerGroup.setDownloadTxDependencies(0); // recursive implementation causes StackOverflowError
peerGroup.addWallet(wallet);//设置钱包,重要
try {
PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), PackageManager.GET_ACTIVITIES);
peerGroup.setUserAgent(USER_AGENT, packageInfo.versionName);
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
}
peerGroup.setMaxConnections(8);
int connectTimeout = (int) (15 * DateUtils.SECOND_IN_MILLIS);
peerGroup.setConnectTimeoutMillis(connectTimeout);
int discoveryTimeout = (int) (10 * DateUtils.SECOND_IN_MILLIS);
peerGroup.addConnectedEventListener(mPeerConnectedEventListener);
peerGroup.addDisconnectedEventListener(mPeerDisconnectedEventListener);
peerGroup.addDiscoveredEventListener(mPeerDiscoveredEventListener);
peerGroup.setPeerDiscoveryTimeoutMillis(discoveryTimeout);
//添加节点探索器,重要
peerGroup.addPeerDiscovery(new PeerDiscovery() {
private final PeerDiscovery normalPeerDiscovery = MultiplexingDiscovery
.forServices(Constants.NETWORK_PARAMETERS, 0);
@Override
public InetSocketAddress[] getPeers(final long services, final long timeoutValue,
final TimeUnit timeoutUnit) throws PeerDiscoveryException {
return normalPeerDiscovery.getPeers(services, timeoutValue, timeoutUnit);
}
@Override
public void shutdown() {
normalPeerDiscovery.shutdown();
}
});
peerGroup.startAsync();
peerGroup.startBlockChainDownload(null);
}
比特币收款
获取测试用比特币:https://testnet.manu.backend.hamburg/faucet
刚收到的币可能需要几分钟后才能使用
//监听比特币接受事件
wallet.addCoinsReceivedEventListener(mWalletListener);
//刷新余额
Coin balance = wallet.getBalance(Wallet.BalanceType.ESTIMATED);
比特币转账
比特币测试链转账查询
创建一个Tx,对Tx进行签名,对Tx进行P2P网络广播
Address address = Address.fromBase58(Constants.NETWORK_PARAMETERS, to);
//转账金额,以mBTC为单位
Coin coin = MonetaryFormat.MBTC.parse(amount);
//创建请求
SendRequest sendRequest = SendRequest.to(address, coin);
try {
//创建Transaction
Transaction transaction = wallet.sendCoinsOffline(sendRequest);
//通过P2P广播
BlockChainService.broadcastTransaction(BitcoinWalletActivity.this, transaction);
} catch (InsufficientMoneyException e) {
Toast.makeText(this, e.getLocalizedMessage(), Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
public static void broadcastTransaction(Context context, Transaction transaction) {
Intent intent = new Intent(ACTION_BROADCAST_TRANSACTION, null, context, BlockChainService.class);
intent.putExtra(ACTION_BROADCAST_TRANSACTION_HASH, transaction.getHash().getBytes());
context.startService(intent);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: ");
if (intent != null) {
byte[] txHash = intent.getByteArrayExtra("tx");
if (txHash != null) {
Sha256Hash sha256Hash = Sha256Hash.wrap(txHash);
Transaction transaction = BitcoinWalletManager.getInstance().getWallet().getTransaction(sha256Hash);
peerGroup.broadcastTransaction(transaction);
Log.d(TAG, "onStartCommand: " + sha256Hash.toString());
}
}
return super.onStartCommand(intent, flags, startId);
}
以太坊钱包
https://github.com/ethereumbook/ethereumbook/blob/develop/wallets.asciidoc
以太坊钱包功能与比特币钱包功能类似,获取用户余额,管理地址和密钥,转账、智能合约调用。以太坊钱包一般不用在本地维护区块链数据,只需要使用JSON-RPC访问
钱包文件
KeyStore = 私钥 + 密码
如果使用ImToken创建钱包,创建了助记词,密码用来加密钱包地址对应的子私钥,加密的结果就是Keystore.
{
"address": "001d3f1ef827552ae1114027bd3ecf1f086ba0f9",
"crypto": {
"cipher": "aes-128-ctr",
"ciphertext": "233a9f4d236ed0c13394b504b6da5df02587c8bf1ad8946f6f2b58f055507ece",
"cipherparams": {
"iv": "d10c6ec5bae81b6cb9144de81037fa15"
},
"kdf": "scrypt",
"kdfparams": {
"dklen": 32,
"n": 262144,
"p": 1,
"r": 8,
"salt": "99d37a47c7c9429c66976f643f386a61b78b97f3246adca89abe4245d2788407"
},
"mac": "594c8df1c8ee0ded8255a50caf07e8c12061fd859f4b7c76ab704b17c957e842"
},
"id": "4fcb2ba4-ccdb-424f-89d5-26cce304bf9c",
"version": 3
}
以太坊钱包地址创建过程
1、使用Secp256k1创建公私钥
2、通过Keccak算法得到公钥Hash值,进而得到长度为40的地址字符串
3、一般的,会在地址字符串签名加前缀"0x"
Web3j创建钱包
Web3j
添加Web3j依赖
implementation 'org.web3j:core:3.3.1-android'
创建新钱包
这里不涉及BIP协议,为非确定性钱包
Wallet.createStandard() 出现OOM, Out of Memory
https://juejin.im/post/5b4b07f8e51d45199060fe1f
File walletDir = contextWrapper.getDir("eth", Context.MODE_PRIVATE);
//生成密钥对
ECKeyPair ecKeyPair = Keys.createEcKeyPair();
//WalletFile = KeyStore
WalletFile wallet = Wallet.createLight(PASSWORD, ecKeyPair);
String walletFileName = getWalletFileName(wallet);
File destination = new File(walletDir, walletFileName);
objectMapper.writeValue(destination, wallet);
加载钱包文件
File[] files = walletDir.listFiles();
wallet = objectMapper.readValue(files[0], WalletFile.class);
通过助记词创建钱包
涉及BIP协议,但没有遵循bitcoin地址只使用一次的原则,钱包一般只使用派生出来第一个地址
可通过工具检查派生的地址是否正确
//创建助记词
public List createMnemonics() throws MnemonicException.MnemonicLengthException {
SecureRandom secureRandom = new SecureRandom();
byte[] entropy = new byte[DeterministicSeed.DEFAULT_SEED_ENTROPY_BITS / 8];
secureRandom.nextBytes(entropy);
return MnemonicCode.INSTANCE.toMnemonic(entropy);
}
//m / 44' / 60' / 0' / 0
//Hardened意思就是派生加固,防止获取到一个子私钥之后可以派生出后面的子私钥
//必须还有上一级的父私钥才能派生
public static final ImmutableList BIP44_ETH_ACCOUNT_ZERO_PATH =
ImmutableList.of(new ChildNumber(44, true), new ChildNumber(60, true),
ChildNumber.ZERO_HARDENED, ChildNumber.ZERO);
//通过助记词生成HD钱包
public void onCreateWallet(View view) {
byte[] seed = MnemonicCode.toSeed(words, "");
DeterministicKey masterPrivateKey = HDKeyDerivation.createMasterPrivateKey(seed);
DeterministicHierarchy deterministicHierarchy = new DeterministicHierarchy(masterPrivateKey);
// m / 44' / 60' / 0' / 0 / 0
DeterministicKey deterministicKey = deterministicHierarchy
.deriveChild(BIP44_ETH_ACCOUNT_ZERO_PATH, false, true, new ChildNumber(0));
byte[] bytes = deterministicKey.getPrivKeyBytes();
ECKeyPair keyPair = ECKeyPair.create(bytes);
try {
WalletFile walletFile = Wallet.createLight(PASSWORD, keyPair);
String address = walletFile.getAddress();
mAddress.setText("0x" + address);
} catch (CipherException e) {
e.printStackTrace();
}
}
导出钱包
导出KeyStore
public String exportKeyStore(WalletFile wallet) {
try {
return objectMapper.writeValueAsString(wallet);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return null;
}
导出私钥
public String exportPrivateKey(WalletFile wallet) {
try {
ECKeyPair ecKeyPair = Wallet.decrypt(PASSWORD, wallet);
BigInteger privateKey = ecKeyPair.getPrivateKey();
return Numeric.toHexStringNoPrefixZeroPadded(privateKey, Keys.PRIVATE_KEY_LENGTH_IN_HEX);
} catch (CipherException e) {
e.printStackTrace();
}
return null;
}
导出助记词
一般可以将助记词加密存储,导出时解密。注意无法从KeyStore或者私钥导出助记词。
例如:使用IMToken导入私钥或者KeyStore创建的钱包,没有导出助记词的功能
如果是通过助记词创建的,就会有导出助记词的功能
ETH交易
获取Robsten测试网络ETH
查询余额
private Web3j mWeb3j = Web3jFactory.build(new HttpService("https://ropsten.infura.io/1UoO4I/"));
BigInteger balance = mWeb3j.ethGetBalance(mAddress, DefaultBlockParameterName.LATEST).send().getBalance();
BigDecimal balance = Convert.fromWei(balance.toString(), Convert.Unit.ETHER);
ETH转账
转账记录查询
BigInteger transactionCount = mWeb3j.ethGetTransactionCount(mAddress, DefaultBlockParameterName.LATEST).send().getTransactionCount();
BigInteger gasPrice = mWeb3j.ethGasPrice().send().getGasPrice();
BigInteger gasLimit = new BigInteger("200000");
BigDecimal value = Convert.toWei(mAmountEdit.getText().toString().trim(), Convert.Unit.ETHER);
String to = mToAddressEdit.getText().toString().trim();
RawTransaction etherTransaction = RawTransaction.createEtherTransaction(transactionCount, gasPrice, gasLimit, to, value.toBigInteger());
ECKeyPair ecKeyPair = Wallet.decrypt("a12345678", mWalletFile);
Credentials credentials = Credentials.create(ecKeyPair);
byte[] bytes = TransactionEncoder.signMessage(etherTransaction, credentials);
String hexValue = Numeric.toHexString(bytes);
String transactionHash = mWeb3j.ethSendRawTransaction(hexValue).send().getTransactionHash();
Token交易
获取某Token余额
调用ERC20代币智能合约,获取当前地址的余额
//创建Function
private Function balanceOf(String owner) {
return new Function("balanceOf",
Collections.singletonList(new Address(owner)),
Collections.singletonList(new TypeReference(){}));
}
Function function = balanceOf(mAddress);
//调用智能合约
String s = callSmartContractFunction(function, CONTRACT_ADDRESS);
List decode = FunctionReturnDecoder.decode(s, function.getOutputParameters());
if (decode != null && decode.size() > 0) {
Uint256 type = (Uint256) decode.get(0);
BigInteger tokenBalance = type.getValue();
}
private String callSmartContractFunction(
Function function, String contractAddress) throws Exception {
String encodedFunction = FunctionEncoder.encode(function);
org.web3j.protocol.core.methods.response.EthCall response = mWeb3j.ethCall(
Transaction.createEthCallTransaction(
mAddress, contractAddress, encodedFunction),
DefaultBlockParameterName.LATEST)
.sendAsync().get();
return response.getValue();
}
Token转账
//创建Function
private Function transfer(String to, BigInteger value) {
return new Function(
"transfer",
Arrays.asList(new Address(to), new Uint256(value)),
Collections.singletonList(new TypeReference() {}));
}
Function transfer = transfer(to, new BigInteger(amount));
//获取私钥,进行签名
ECKeyPair ecKeyPair = Wallet.decrypt("a12345678", mWalletFile);
Credentials credentials = Credentials.create(ecKeyPair);
String transactionHash = execute(credentials, transfer, CONTRACT_ADDRESS);
//执行合约调用
private String execute(
Credentials credentials, Function function, String contractAddress) throws Exception {
BigInteger nonce = mWeb3j.ethGetTransactionCount(mAddress, DefaultBlockParameterName.LATEST).send().getTransactionCount();
BigInteger gasPrice = mWeb3j.ethGasPrice().send().getGasPrice();
BigInteger gasLimit = new BigInteger("200000");
String encodedFunction = FunctionEncoder.encode(function);
RawTransaction rawTransaction = RawTransaction.createTransaction(
nonce,
gasPrice,
gasLimit,
contractAddress,
encodedFunction);
byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
String hexValue = Numeric.toHexString(signedMessage);
EthSendTransaction transactionResponse = mWeb3j.ethSendRawTransaction(hexValue)
.sendAsync().get();
return transactionResponse.getTransactionHash();
}