ethereum - Solidity 中的事件触发

Question

我目前正在开发以太坊平台(node.js 和solidity)。我的问题是如何使用 node.js 在solidity(契约(Contract))中触发事件？

Answer 1

这是智能合约中的示例事件定义:

contract Coin {
    //Your smart contract properties...

    // Sample event definition: use 'event' keyword and define the parameters
    event Sent(address from, address to, uint amount);


    function send(address receiver, uint amount) public {
        //Some code for your intended logic...

        //Call the event that will fire at browser (client-side)
        emit Sent(msg.sender, receiver, amount);
    }
}

线下事件 Sent(address from, address to, uint amount);声明一个所谓的“ event ” 在函数 send 的最后一行触发.用户界面(当然还有服务器应用程序)可以监听在区块链上触发的事件，而无需花费太多成本。一旦它被触发，监听器也会收到参数 from , to和 amount ，这使得跟踪交易变得容易。为了监听此事件，您将使用。

将捕获事件并在浏览器控制台中写入一些消息的 Javascript 代码:

Coin.Sent().watch({}, '', function(error, result) {
    if (!error) {
        console.log("Coin transfer: " + result.args.amount +
            " coins were sent from " + result.args.from +
            " to " + result.args.to + ".");
        console.log("Balances now:\n" +
            "Sender: " + Coin.balances.call(result.args.from) +
            "Receiver: " + Coin.balances.call(result.args.to));
    }
})

引用:
http://solidity.readthedocs.io/en/develop/introduction-to-smart-contracts.html