《我学区块链》—— 三十五、智能合约收发 ETH 详解

三十五、智能合约收发 ETH 详解

一、合约接收 ETH

使用合约接收 ETH，需要在智能合约中定义这个函数 function () payable public {}，之后就可以接收ETH了。并在最终需要时调用selfdestruct(owner);杀死合约，取出合约中的所有 ETH 到 owner。

pragma solidity ^0.4.24;
contract NetkillerCashier {

    function () payable public {}

    function claim() public {
        selfdestruct(owner);
    }
}

二、自动退款合约

合约只收取 1 ETH 多余 ETH 将退给用户。

pragma solidity ^0.4.24;

contract Refund {
    address owner = 0x0;
    uint256 ticket = 1 ether;
    
    constructor() public payable {
        owner = msg.sender;
    }

    function () public payable {
        require(msg.value >= ticket);
        if (msg.value > ticket) {
            uint refundFee = msg.value - ticket;
            msg.sender.transfer(refundFee);
        }
    }
}

三、收款自动转账合约

合约收到 ETH 后自动转到 owner 账号中，所消耗的 gas 全部由发起转账的账号支付。

pragma solidity ^0.4.24;

contract NetkillerCashier {

    address public owner;

    constructor() public payable {
        owner = msg.sender;
    }

    function () payable public {
        owner.transfer(msg.value);
    }
}

四、指定账号提取 ETH

pragma solidity ^0.4.24;

contract NetkillerCashier {

    address public owner;
    uint public amount;
    
    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }
    
    constructor() public {
        owner = msg.sender;
    }

    function () public payable {
        amount += msg.value;
    }

	function transferOwnership(address newOwner) onlyOwner public {
        if (newOwner != address(0)) {
            owner = newOwner;
        }
    }

    function withdraw() onlyOwner public {
        msg.sender.transfer(amount);
        amount = 0;
    }
}

function transferOwnership(address newOwner) // 可以修改合约所有人
function withdraw()	// 提取 ETH 到 owner

参考资料：https://my.oschina.net/neochen/blog/1862347