这一篇中我们来完成Dapp的界面编写。
页面布局
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>ERC20代币合约</title>
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
crossorigin="anonymous">
</head>
<body>
<div class="container">
<div class="jumbotron">
<div class="row" style="padding-top:40px;">
<div class="col-xs-12">
<div class="panel panel-default">
<div class="panel-heading">
<div class="h3 text-center">ERC20代币合约</div>
</div>
<div class="panel-body">
<div class="form-group">
<label for="">名称(name)：</label>
<span id="name"></span>
</div>
<div class="form-group">
<label for="">标识符(symbol)：</label>
<span id="symbol"></span>
</div>
<div class="form-group">
<label for="">总额(totalSupply)：</label>
<span id="totalSupply"></span>
</div>
<div class="form-group">
<label for="">当前帐户(account)：</label>
<span id="account"></span>
</div>
<div class="form-group">
<label for="">余额(balanceOf)：</label>
<span id="balanceOf"></span>
</div>
<div class="form-group">
<label for="">从当前账户转移(transfer)：</label>
<div class="input-group">
<span class="input-group-addon">地址</span>
<input class="form-control" id="toAccount">
</div>
<div class="input-group" style="padding-top:10px;">
<span class="input-group-addon">金额</span>
<input type="text" class="form-control" id="toValue">
</div>
</div>
<button class="btn btn-primary btn-block" id="btnTransfer">提交</button>
</div>
</div>
</div>
</div>
</div>
</div>
为了让界面美观些，引入了bootstrap框架。限于篇幅，这里并不演示transferFrom approve allowance 等方法调用。原理是一样的。
脚本调用
接下来是脚本部分，简单起见，都放在一个文件中。
<script src="https://cdn.bootcss.com/jquery/1.12.4/jquery.min.js"></script>
<script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa"
crossorigin="anonymous"></script>
<script src="./js/web3.min.js"></script>
<script>
var web3;
var erc20;
$(document).ready(function () {
web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
var account = web3.eth.accounts[0];
web3.eth.defaultAccount = web3.eth.accounts[0];
var accountInterval = setInterval(function() {
if (web3.eth.accounts[0] !== account) {
account = web3.eth.accounts[0];
web3.eth.defaultAccount = web3.eth.accounts[0];
updateInterface();
}
}, 100);
startApp()
});
function updateInterface() {
erc20.name(function (error, result) {
if (!error)
$("#name").text(result);
else
console.log(error);
});
erc20.symbol(function (error, result) {
if (!error)
$("#symbol").text(result);
else
console.log(error);
});
erc20.totalSupply(function (error, result) {
if (!error)
$("#totalSupply").text(result);
else
console.log(error);
});
$("#account").text(web3.eth.coinbase);
erc20.balanceOf(web3.eth.defaultAccount, function (error, result) {
if (!error)
$("#balanceOf").text(result);
else
console.log(error);
});
}
function startApp() {
var abi =[{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"candy","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"},{"indexed":true,"name":"_spender","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Approval","type":"event"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"}],"name":"Candy","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"}];
var address = "0xdda6327139485221633a1fcd65f4ac932e60a2e1";
erc20 = web3.eth.contract(abi).at(address);
$("#btnTransfer").click(function () {
var toAccount = $("#toAccount").val();
var toValue = $("#toValue").val();
erc20.transfer( toAccount, toValue, function () {
updateInterface();
});
});
$("#btnCandy").click(function () {
var toAccount = $("#toAccount").val();
var toValue = $("#toValue").val();
erc20.candy(function () {
updateInterface();
});
});
if(web3.eth.defaultAccount) {
updateInterface();
}
}
</script>
</body>
</html>
这里http://localhost:8545 是本地geth节点的rpc端口。
var accountInterval = setInterval(function() {
if (web3.eth.accounts[0] !== account) {
account = web3.eth.accounts[0];
web3.eth.defaultAccount = web3.eth.accounts[0];
updateInterface();
}
}, 100);
这段代码是定时查询当前账户是否有变动，如果变动就刷新页面。
abi的值，可以在remix编译完合约后，点Details按钮找到。
address 的值是部署完合约后的实际地址，需要根据实际填写。
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