【PHP】基于币安链，一个完整的USDT转账示例

目录

1.先查询余额是否充足

2.动态获取nonce

3.动态获取gasPrice

4.动态获取estimateGas

5.发送交易

6.完整示例

---

环境要求：

php7.4+

依赖：

"web3p/ethereum-tx": "^0.4.3",
"web3p/web3.php": "dev-master"

参考文档：

Geth Proxy | BscScan

1.先查询余额是否充足

        // 方法一：web3查询$rpcUrl = 'https://bsc-dataseed.binance.org/';// 初始化Web3实例$web3 = new Web3(new HttpProvider($rpcUrl));// USDT合约ABI（简化版）$usdtAbi = '[{"constant":true,"inputs":[{"name":"who","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"type":"function"}]';// 转账前余额查询$currentBalance = $this->getUsdtBalance($web3, $usdtAbi, $contractAddress, $fromAddress);if ($currentBalance < $amount) {throw new Exception("账户余额不足");}// 查询余额函数public function getUsdtBalance($web3, $usdtAbi, $contractAddress, $address) {$contract = new Contract($web3->provider, $usdtAbi);$balance = 0;$contract->at($contractAddress)->call('balanceOf', $address, function ($err, $result) use (&$balance) {if ($err !== null) {throw new Exception("余额查询失败: " . $err->getMessage());}$balance = $result[0]->toString();});return $balance / pow(10, 18); // 转换为标准单位}// 方法二：根据币安官方文档https://docs.bscscan.com/api-endpoints/tokens/*** 获取账户代币余额*/public function getBalance($contract,$address){$query = ['module' => 'account','action' => 'tokenbalance','contractaddress' => $contract,'address'=>$address,'tag'=>'latest','apikey' => $this->apikey,];$data = $this->get($query);return $data['result'];}/*** 请求处理*/private function get($query) {$client = new Client();$response = $client->get($this->url."api", ['query' => $query]);if ($response->getStatusCode() != 200) {throw new Exception('Web3 接口请求异常');}return json_decode($response->getBody()->getContents(), true);}

2.动态获取nonce

    // 方法一：官方文档/*** 获取nonce* 参考文档：https://docs.bscscan.com/api-endpoints/geth-parity-proxy#eth_gettransactioncount*/private function getNonce($address) {$query = ['module' => 'proxy','action' => 'eth_getTransactionCount','address' => $address,'tag' => 'pending','apikey' => $this->apikey,];$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 getNonce 错误:'.$data['error']['code'].$data['error']['message']);}}// 方法二：web3$web3->eth->getTransactionCount($fromAddress, 'latest', function ($err, $nonceResult) use (&$nonce) {if ($err) throw new Exception($err->getMessage());$nonce = hexdec($nonceResult->toString());});

3.动态获取gasPrice

    // 方法一：web3$web3->eth->gasPrice(function ($err, $gasPriceResult) use (&$gasPrice) {if ($err) throw new Exception($err->getMessage());$gasPrice = $gasPriceResult->toString();});// 方法二：官方文档/*** 获取gasPrice*/private function gasPrice() {$query = ['module' => 'proxy','action' => 'eth_gasPrice','apikey' => $this->apikey,];$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 gasPrice 错误:'.$data['error']['code'].$data['error']['message']);}}

4.动态获取estimateGas

    /*** 获取estimateGas* https://docs.bscscan.com/api-endpoints/geth-parity-proxy#eth_estimategas* @param $txParams*/private function estimateGas($txParams) {$query = array_merge($txParams,['module' => 'proxy','action' => 'eth_estimateGas','apikey' => $this->apikey,]);$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 estimateGas 错误:'.$data['error']['code'].$data['error']['message']);}}

5.发送交易

    /*** https://docs.bscscan.com/api-endpoints/geth-parity-proxy#eth_gettransactioncount* @throws Exception*/private function sendRawTransaction($hex) {$query = ['module' => 'proxy','action' => 'eth_sendRawTransaction','hex' => $hex,'apikey' => $this->apikey,];$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 send 错误:'.$data['error']['code'].$data['error']['message']);}}

6.完整示例

<?phpnamespace app\common\library;use Exception;
use GuzzleHttp\Client;
use Web3\Contract;
use Web3\Providers\HttpProvider;
use Web3\Utils;
use Web3\Web3;
use Web3p\EthereumTx\Transaction;class Transfer
{public $apikey = "xxxx";public $url = "https://api.bscscan.com/";public $chainId = 56;public function send($amount, $toAddress){$contractAddress = '0x55d398326f99059ff775485246999027b3197955'; // usdt的合约地址$fromAddress = '';$fromAddressKey = '';if(empty($fromAddress) || empty($fromAddressKey)){throw new Exception('请先配置from_address和from_address_key');}$rpcUrl = 'https://bsc-dataseed.binance.org/';// 初始化Web3实例$web3 = new Web3(new HttpProvider($rpcUrl));// USDT合约ABI（简化版）$usdtAbi = '[{"constant":true,"inputs":[{"name":"who","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"type":"function"}]';// 转账前余额查询$currentBalance = $this->getUsdtBalance($web3, $usdtAbi, $contractAddress, $fromAddress);if ($currentBalance < $amount) {throw new Exception("账户余额不足");}// 将金额转换为字符串，并移除科学计数法$amountWei = (int)bcmul($amount,  pow(10, 18)); // 转换为wei单位$nonce = $this->getNonce($fromAddress);$gasPrice = $this->gasPrice();// 正确编码data字段（transfer方法签名+参数）$toParam = str_pad(substr($toAddress, 2), 64, '0', STR_PAD_LEFT); // 地址参数编码$amountHex = str_pad(Utils::toHex($amountWei), 64, '0', STR_PAD_LEFT); // 32字节金额$data = ['0xa9059cbb',$toParam,$amountHex,];// 构建交易参数$txParams = ['from' => $fromAddress,'to' => $contractAddress,'value' => '0x0', // ERC20转账必须为0'gasPrice' => $gasPrice,'data' => implode('', $data),];$gasLimit = $this->estimateGas($txParams);$txData = ['nonce' => $nonce,'from' => strtolower($fromAddress),'to' => strtolower($contractAddress),'gas' => $gasLimit, // Gas Limit（合约交互需更高gas）'gasPrice' => $gasPrice, // 5 Gwei'chainId' => $this->chainId,'value' => '0x0','data' => implode('', $data)];$transaction = new Transaction($txData);$hex = $transaction->sign($fromAddressKey);return $this->sendRawTransaction('0x' . $hex);}/*** @throws Exception*/private function sendRawTransaction($hex) {$query = ['module' => 'proxy','action' => 'eth_sendRawTransaction','hex' => $hex,'apikey' => $this->apikey,];$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 send 错误:'.$data['error']['code'].$data['error']['message']);}}/*** 获取nonce*/private function getNonce($address) {$query = ['module' => 'proxy','action' => 'eth_getTransactionCount','address' => $address,'tag' => 'pending','apikey' => $this->apikey,];$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 getNonce 错误:'.$data['error']['code'].$data['error']['message']);}}/*** 获取gasPrice*/private function gasPrice() {$query = ['module' => 'proxy','action' => 'eth_gasPrice','apikey' => $this->apikey,];$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 gasPrice 错误:'.$data['error']['code'].$data['error']['message']);}}/*** 获取estimateGas* @param $txParams*/private function estimateGas($txParams) {$query = array_merge($txParams,['module' => 'proxy','action' => 'eth_estimateGas','apikey' => $this->apikey,]);$data = $this->get($query);if(isset($data['result'])){return $data['result'];}else{throw new Exception('Web3 estimateGas 错误:'.$data['error']['code'].$data['error']['message']);}}/*** 请求处理*/private function get($query) {$client = new Client();$response = $client->get($this->url."api", ['query' => $query]);if ($response->getStatusCode() != 200) {throw new Exception('Web3 接口请求异常');}return json_decode($response->getBody()->getContents(), true);}// 查询余额函数public function getUsdtBalance($web3, $usdtAbi, $contractAddress, $address) {$contract = new Contract($web3->provider, $usdtAbi);$balance = 0;$contract->at($contractAddress)->call('balanceOf', $address, function ($err, $result) use (&$balance) {if ($err !== null) {throw new Exception("余额查询失败: " . $err->getMessage());}$balance = $result[0]->toString();});return $balance / pow(10, 18); // 转换为标准单位}
}