智能合约开发

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1、智能合约开发语言：solidityIDE：mix-ide or whatever实例编写，Conference.sol :contract Conference address public organizer;mapping (address = uint) public registrantsPaid;uint public numRegistrants;uint public quota;event Deposit(address _from, uint _amount); / so you can log these eventsevent Refund(address _to, ui

2、nt _amount);function Conference() / Constructororganizer = msg.sender;quota = 500;numRegistrants = 0;function buyTicket() public returns (bool success) if (numRegistrants = quota) return false; registrantsPaidmsg.sender = msg.value;numRegistrants+;Deposit(msg.sender, msg.value);return true;function

3、changeQuota(uint newquota) public if (msg.sender != organizer) return; quota = newquota;function refundTicket(address recipient, uint amount) public if (msg.sender != organizer) return; if (registrantsPaidrecipient = amount) address myAddress = this;if (myAddress.balance = amount) recipient.send(amo

4、unt);registrantsPaidrecipient = 0;numRegistrants-;Refund(recipient, amount);function destroy() / so funds not locked in contract foreverif (msg.sender = organizer) suicide(organizer); / send funds to organizer二智能合约部署使用truffle部署智能合约的步骤：1. truffle init (在新目录中)= 创建truffle项目目录结构2. 编写合约代码，保存到 con tracts/

5、YourC on tractName.sol 文件。3. 把合约名字加到config/app.json的contracts部分。4. 启动以太坊节点(例如在另一个终端里面运行testrpc )。5- truffle deploy (在truffle项目目录中)添加一个智能合约。在truffle init执行后或是一个现有的项目目录中，复制粘帖上面的会议合约到 con tracts/C onferen ce.sol 文件中。然后打开truffle.js文件，把Conference加入deploy数组中。19 deploy:20 / Names of contracts that should b

6、e deployed to th亡 network.21 Conference22 ,启动 testrpco在另一个终端中启动testrpc。编译或部署。执行truffle compile看一下合约是否能成功编译，或者直接 truffle deploy 一步完成编译和部 署。这条命令会把部署好的合约的地址和ABI(应用接口)加入到配置文件中，这样之后的 truffle test和truffle build步骤可以使用这些信息。出错了？编译是否成功了？记住，错误信息即可能出现在testrpc终端也可能出现在truffle终 端。重启节点后记得重新部署！如果你停止了 testrpc节点，下一次使用

7、任何合约之前切记使用 truffle deploy 重新部署。 testrpc在每一次重启之后都会回到完全空白的状态。部署truffle deploy启动服务truffle serve启动服务后，可以在浏览器访问项目：http:/loca山ost:8080/三 智能合约测试用例编写/ 测试用例编写/把项目目录test/中的example.js文件重命名为conference.js，内容修改为如下，然后启动testrpc后，运行/ Truffle testcontract(Conference, function(accounts) / 1.初始化一个新的Conference，然后检查变量是否都

8、正确赋值it(Initial conference settings should match, function(done) var conference = Conference.at(Conference.deployed_address);/ same as previous example up to hereConference.new( from: accounts。 ).then(function(conference) conference.quota.call().then(function(quota) assert.equal(quota, 500, Quota doe

9、snt match!);).then( function() return conference.numRegistrants.call();).then( function(num) assert.equal(num, 0, Registrants should be zero!);return conference.organizer.call();).then( function(organizer) assert.equal(organizer, accounts。, Owner doesnt match!);done(); / to stop these tests earlier,

10、 move this up).catch(done);).catch(done);)；/ 2.测试合约函数调用 测试改变Quote变量的函数能否工作it(Should update quota, function(done) var c = Conference.at(Conference.deployed_address);Conference.new(from: accounts。 ).then(function(conference) conference.quota.call().then(function(quota) assert.equal(quota, 500, Quota d

11、oesnt match!);).then( function() return conference.changeQuota(300);).then( function(result) / result here is a transaction hashconsole.log(result); / if you were to print this out it d be long hex - the transaction hash return conference.quota.call().then( function(quota) assert.equal(quota, 300, N

12、ew quota is not correct!);done();).catch(done);).catch(done););/ 3.测试交易调用一个需要发起人发送资金的函数。a ticketvar c = Conference.at(Conference.deployed_address);Conference.new( from: accounts。 ).then(function(conference) var ticketPrice = web3.toWei(.O5, ether);var initialBalance = web3.eth.getBalance(conference.

13、address).toNumber();conference.buyTicket( from: accounts1, value: ticketPrice ).then(function() var newBalance = web3.eth.getBalance(conference.address).toNumber();var difference = newBalance - initialBalance;assert.equal(difference, ticketPrice, Difference should be what was sent); return conferenc

14、e.numRegistrants.call();).then(function(num) assert.equal(num, 1, there should be 1 registrant);return conference.registrantsPaid.call(accountsl);).then(function(amount) assert.equal(amount.toNumber(), ticketPrice, Senders paid but is not listed); done();).catch(done);).catch(done);)；/ 4.测试包含转账的合约最后

15、，为了完整性，确认一下refundTicket方法能正常工作，而且只有会议组 织者能调用it(Should issue a refund by owner only, function(done) var c = Conference.at(Conference.deployed_address);Conference.new( from: accounts0 ).then(function(conference) var ticketPrice = web3.toWei(.O5, ether);var initialBalance = web3.eth.getBalance(conferen

16、ce.address).toNumber();conference.buyTicket( from: accounts1, value: ticketPrice ).then(function() var newBalance = web3.eth.getBalance(conference.address).toNumber();var difference = newBalance - initialBalance;assert.equal(difference, ticketPrice, Difference should be what was sent); / same as bef

17、ore up to here/ Now try to issue refund as second user - should failreturn conference.refundTicket(accountsl, ticketPrice, from: accountsl);).then(function() var balance = web3.eth.getBalance(conference.address).toNumber();assert.equal(web3.toBigNumber(balance), ticketPrice, Balance should be unchan

18、ged);/ Now try to issue refund as organizer/owner - should workreturn conference.refundTicket(accountsl, ticketPrice, from: accounts。);).then(function() var postRefundBalance = web3.eth.getBalance(conference.address).toNumber(); assert.equal(postRefundBalance, initialBalance, Balance should be initi

19、al balance); done();).catch(done);).catch(done););)；/ Solidity编译器提供了一个参数让你可以从命令行获取合约的Gas开销概要/ solc -gas Conference.sol/ 输出：= Conference =Gas estimation:construction:45438 + 271200 =316638external:registrantsPaid(address): 323organizer():282refundTicket(address,uint256):destroy(): 384changeQuota(uint

20、256):20370quota():333numRegistrants():355buyTicket():42023internal:四 为合约创建 DApp 界面1. 修改 app/javascripts/app.js window.onload = function。var accounts = web3.eth.accounts;var conference = Conference.at(Conference.deployed_address);$(#confAddress).html(Conference.deployed_address);var myConferencelnsta

21、nce;Conference.new(from: accounts。, gas: 3141592).then(function(conf) myConferencelnstance = conf; checkValues(););/ Check Valuesfunction checkValues() myConferenceInstance.quota.call().then(function(quota) $(input#confQuota).val(quota);return myConferenceInstance.organizer.call();).then(function(or

22、ganizer) $(input#confOrganizer).val(organizer);return myConferenceInstance.numRegistrants.call();).then(function(num) $(#numRegistrants).html(num.toNumber();return myConferenceInstance.organizer.call();)；/ Change Quotafunction changeQuota(val) myConferenceInstance.changeQuota(val, from: accounts0).t

23、hen( function。return myConferenceInstance.quota.call();).then(function(quota) if (quota = val) var msgResult;msgResult = Change successful; else msgResult = Change failed;$(#changeQuotaResult).html(msgResult););/ buyTicketfunction buyTicket(buyerAddress, ticketPrice) myConferenceInstance.buyTicket(

24、from: buyerAddress, value: ticketPrice ).then( function() return myConferenceInstance.numRegistrants.call();).then(function(num) $(#numRegistrants).html(num.toNumber();return myConferencelnstance.registrantsPaid.call(buyerAddress);).then(function(valuePaid) var msgResult;if (valuePaid.toNumber() = t

25、icketPrice) msgResult = Purchase successful; else msgResult = Purchase failed;$(#buyTicketResult).html(msgResult);function refundTicket(buyerAddress, ticketPrice) var msgResult;myConferenceInstance.registrantsPaid.call(buyerAddress).then(function(result) if (result.toNumber() = 0) $(#refundTicketRes

26、ult).html(Buyer is not registered - no refund!); else myConferenceInstance.refundTicket(buyerAddress,ticketPrice, from: accountsO).then(function。return myConferenceInstance.numRegistrants.call();).then(function(num) $(#numRegistrants).html(num.toNumber(); return myConferencelnstance.registrantsPaid.

27、call(buyerAddress);).then(function(valuePaid) if (valuePaid.toNumber() = 0) msgResult = Refund successful; else msgResult = Refund failed;$(#refundTicketResult).html(msgResult););/ createWalletfunction createWallet(password) var msgResult;var secretSeed = lightwallet.keystore.generateRandomSeed();$(

28、#seed).html(secretSeed);lightwallet.keystore.deriveKeyFromPassword(password, function (err, pwDerivedKey) console.log(createWallet);var keystore = new lightwallet.keystore(secretSeed, pwDerivedKey);/ generate one new address/private key pairs/ the corresponding private keys are also encryptedkeystor

29、e.generateNewAddress(pwDerivedKey);var address = keystore.getAddresses()0;var privateKey = keystore.exportPrivateKey(address, pwDerivedKey);console.log(address);$(#wallet).html(Ox+address);$(#privateKey).html(privateKey);$(#balance).html(getBalance(address);/ Now set ks as transaction_signer in the

30、hooked web3 provider/ and you can start using web3 using the keys/addresses in ks!switchToHooked3(keystore););function getBalance(address) return web3.fromWei(web3.eth.getBalance(address).toNumber(), ether);/ switch to hooked3webprovider which allows for external Tx signing/ (rather than signing fro

31、m a wallet in the Ethereum client)function switchToHooked3(_keystore) console.log(switchToHooked3);var web3Provider = new HookedWeb3Provider(host: http:/localhost:8545, / check what using in truffle.jstransaction_signer: _keystore)；web3.setProvider(web3Provider);function fundEth(newAddress, amt) con

32、sole.log(fundEth);var fromAddr = accounts。; / default owner address of clientvar toAddr = newAddress;var valueEth = amt;var value = parseFloat(valueEth)*1.0el8;var gasPrice = 1000000000000;var gas = 50000;web3.eth.sendTransaction(from: fromAddr, to: toAddr, value: value, function (err, txhash) if (e

33、rr) console.log(ERROR: + err)console.log(txhash: + txhash + ( + amt + in ETH sent);$(#balance).html(getBalance(toAddr););/ Wire up the UI elements$(#changeQuota).click(function() var val = $(#confQuota).val(); changeQuota(val););$(#buyTicket).click(function() var val = $(#ticketPrice).val();var buye

34、rAddress = $(#buyerAddress).val();buyTicket(buyerAddress, web3.toWei(val););$(#refundTicket).click(function() var val = $(#ticketPrice).val();var buyerAddress = $(#refBuyerAddress).val();refundTicket(buyerAddress, web3.toWei(val););$(#createWallet).click(function() var val = $(#password).val();if (!

35、val) $(”#password”).val(”PASSWORD NEEDED”).css(”color”, red);$(#password).click(function() $(”#password”).val(”).css(”color”, black);); else createWallet(val););var address = $(#wallet).html();fundEth(address, 1);)；$(#checkBalance).click(function() var address = $(#wallet).html();$(#balance).html(ge

36、tBalance(address););/ Set value of wallet to accounts1$(#buyerAddress).val(accounts1); $(#refBuyerAddress).val(accounts1);2.修改 index.htmlConference DAppbody font-family: Arial, sans-serif;.section margin: 20px;button padding: 5px 16px;border-radius: 4px;button#changeQuota background-color: yellow; b

37、utton#buyTicket background-color: #98fb9 8; button#refundTicket background-color: pink; button#createWallet background-color: #add8e6; #seed color: green;vscript type=text/javascript src=vscript src=./app.jsConference DAppContract deployed at: Organizer: vinput type=text id=confOrganizer /Quota: vin

38、put type=text id=confQuota /vbutton id=changeQuotaChangevspan id=changeQuotaResultvdiv class=sectionRegistrants: vspan id=numRegistrants0vdiv class=sectionBuy a Ticketv/h2Ticket Price: vinput type=text id=ticketPrice value=0.05 /Buyer Address: vinput type=text id=buyerAddress /vbutton id=buyTicketBu

39、y Ticketv/buttonvspan id=buyTicketResultv/spanv/divvhr/Refund a TicketTicket Price: Buyer Address: vinput type=text id=refBuyerAddress / vbutton id=refundTicketRefund Ticket vspan id=refundTicketResultCreate a WalletPassword: vinput type=text id=password /vbutton id=createWalletCreate Walletvbutton

40、id=fundWalletFund Wallet with 1 ETHv/buttonvbr/Your Wallet Secret Seed: vspan id=seedv/span vbr/vbr/Your New Wallet Address: vspan id=walletv/span vbr/vbr/Your New Wallet Private Key: vspan id=privateKeyv/span vbr/vbr/Wallet Balance: vspan id=balancev/span vbr/vbr/vbutton id=checkBalanceCheck Balanc

41、ev/button v/divv/bodyv/html3. 最终效果:应用 个人 购物 新闻 任务学习日常禅读 屬百度一下校招Conference DAppContract deployed at:0x34dc41 blbf4cfcb 9968e172MB23+c0ra 1 bdfbcaOrganizer: &xT1 c414917ba127eaebQuota: 100ChangeRegistrants: 0Buy a TicketTicket Price: a.05Buyer Address: 0Kra5s3tb929aa62eC1E 3uy TicketRefund a TicketTicket Price: 0.05B uyer Add re ss: 0xfB5s3tb 92 9aa62 eC1E Reftj n d TicketCreate a WalletPassword:Your Wallet Secret Seed:Ytour N ew Wai let Addre&s:Ybur N 已w Wai let Private Key:Wallet Balance:Ch&ck BalanceCreate Wallet Fun-d Wallet with 1 ETH