以太坊教程- Web3.js 开发基础

简介

web3.js 是一个通过RPC 调用和本地以太坊节点进行通信的js库。web3.js可以与任何暴露了RPC接口的以太坊节点连接。
web3中提供了eth对象 - web3.eth来与以太坊区块链进行交互。

在github上获得代码

安装 Testrpc

安装Ethereum客户端来支持JSON RPC API调用开发环境，推荐使用EthereumJS。
安装命令：

sudo npm install -g ethereumjs-testrpc

启动 testrpc
在命令行执行

testrpc
EthereumJS TestRPC v6.0.3 (ganache-core: 2.0.2)Available Accounts
==================
(0) 0x1abb473c627e690c048dbf7a9f9cc54b25dea42a
(1) 0xd50fadba656c8f78916f9c1a1b78fd3d35dad0aa
(2) 0x69e0159cf8e6fc81e8e71479aea0e8984d7daf48
(3) 0x5f1ebce982445a02ff4530f4d53cd09cb2a6addf
(4) 0x746f6a0192cf42001ded53a55932a6dff754e143
(5) 0x685dcca08e5efc905a300eff68bf2e8a81989966
(6) 0x08eed3a1a801be6af543105cb9bfc27b6401c020
(7) 0xc8fd99bde94fbfab654c8cffda6047b16306cc07
(8) 0xc28e0b677883f809faa1eaf563a5f4b794dcbaeb
(9) 0xd02b16bbaa70b2cba4ea173009f2fdf829a8ffbaPrivate Keys
==================
(0) d233ec4635ed0fe5c61977c9442d6233c599cd3591107b9a017f7ea6077da3bc
(1) a02a88b2c04aed72b55cdd6f6212e1f560dd02767f0a03627fac97b64b64086d
(2) 833dd28ab15388ba162862c365313978dabb96d209c311bca7d9a7bfdb2ecb6f
(3) 47c7ae2635fed1b4f5e442496fd364cdaa91ae6e950b45f36aa4ac6c172cffb5
(4) 4b8ee2ee44eab299cbeff51bbf6fb74572e493409556e728a385dcf9e4dc4f84
(5) 50cdb8a14babddcbb79f14ad7b5cc55e95a0b8ce72659eec1c9b8d798ff52369
(6) becc6dd7a41564aaf3f2f1711eb102032ace0c4e4b561fc7c922ea92f1a81c5a
(7) cc82c2ad095b32bd23e33bc9c3ef6b69ad8b76de07a9e02714760d2fd843efa5
(8) 44f9c35f62ffe1aa3b85bb6e557569beb396ced7d5ab8a75345d9a8ab1283bca
(9) 3d7ec84ed3253366f744a754ccdc2187d65856c2b264e9fbd651c59896aac229HD Wallet
==================
Mnemonic:      tilt oyster obtain car venture party power exclude fire price senior blue
Base HD Path:  m/44'/60'/0'/0/{account_index}Listening on localhost:8545

会自动创建10个账户，每个账户默认有100个以太币。

安装和和获取web3对象

安装
npm: npm install web3
bower: bower install web3
metor: meteor add ethereum:web3
vanilla: dist./web3.min.js
获得web3实例

if (typeof web3 !== 'undefined') {web3 = new Web3(web3.currentProvider);
} else {// set the provider you want from Web3.providersweb3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
}

使用实例

一、账户操作：

获取账户

web3.eth.getAccounts(function(error, result){res.send(result)})

创建新账户

web3.eth.accounts.create();
> {address: "0xb8CE9ab6943e0eCED004cDe8e3bBed6568B2Fa01",privateKey: "0x348ce564d427a3311b6536bbcff9390d69395b06ed6c486954e971d960fe8709",signTransaction: function(tx){...},sign: function(data){...},encrypt: function(password){...}
}web3.eth.accounts.create('2435@#@#@±±±±!!!!678543213456764321§34567543213456785432134567');
> {address: "0xF2CD2AA0c7926743B1D4310b2BC984a0a453c3d4",privateKey: "0xd7325de5c2c1cf0009fac77d3d04a9c004b038883446b065871bc3e831dcd098",signTransaction: function(tx){...},sign: function(data){...},encrypt: function(password){...}
}web3.eth.accounts.create(web3.utils.randomHex(32));
> {address: "0xe78150FaCD36E8EB00291e251424a0515AA1FF05",privateKey: "0xcc505ee6067fba3f6fc2050643379e190e087aeffe5d958ab9f2f3ed3800fa4e",signTransaction: function(tx){...},sign: function(data){...},encrypt: function(password){...}
}

使用私钥创建账户

web3.eth.accounts.privateKeyToAccount(privateKey);

web3.eth.accounts.privateKeyToAccount('0x348ce564d427a3311b6536bbcff9390d69395b06ed6c486954e971d960fe8709');
> {address: '0xb8CE9ab6943e0eCED004cDe8e3bBed6568B2Fa01',privateKey: '0x348ce564d427a3311b6536bbcff9390d69395b06ed6c486954e971d960fe8709',signTransaction: function(tx){...},sign: function(data){...},encrypt: function(password){...}
}web3.eth.accounts.privateKeyToAccount('0x348ce564d427a3311b6536bbcff9390d69395b06ed6c486954e971d960fe8709');
> {address: '0xb8CE9ab6943e0eCED004cDe8e3bBed6568B2Fa01',privateKey: '0x348ce564d427a3311b6536bbcff9390d69395b06ed6c486954e971d960fe8709',signTransaction: function(tx){...},sign: function(data){...},encrypt: function(password){...}
}

使用私钥签名一个交易

web3.eth.accounts.signTransaction(tx, privateKey [, callback]);

web3.eth.accounts.signTransaction({to: '0xF0109fC8DF283027b6285cc889F5aA624EaC1F55',value: '1000000000',gas: 2000000
}, '0x4c0883a69102937d6231471b5dbb6204fe5129617082792ae468d01a3f362318')
.then(console.log);
> {messageHash: '0x88cfbd7e51c7a40540b233cf68b62ad1df3e92462f1c6018d6d67eae0f3b08f5',v: '0x25',r: '0xc9cf86333bcb065d140032ecaab5d9281bde80f21b9687b3e94161de42d51895',s: '0x727a108a0b8d101465414033c3f705a9c7b826e596766046ee1183dbc8aeaa68',rawTransaction: '0xf869808504e3b29200831e848094f0109fc8df283027b6285cc889f5aa624eac1f55843b9aca008025a0c9cf86333bcb065d140032ecaab5d9281bde80f21b9687b3e94161de42d51895a0727a108a0b8d101465414033c3f705a9c7b826e596766046ee1183dbc8aeaa68'
}web3.eth.accounts.signTransaction({to: '0xF0109fC8DF283027b6285cc889F5aA624EaC1F55',value: '1000000000',gas: 2000000,gasPrice: '234567897654321',nonce: 0,chainId: 1
}, '0x4c0883a69102937d6231471b5dbb6204fe5129617082792ae468d01a3f362318')
.then(console.log);
> {messageHash: '0x6893a6ee8df79b0f5d64a180cd1ef35d030f3e296a5361cf04d02ce720d32ec5',r: '0x9ebb6ca057a0535d6186462bc0b465b561c94a295bdb0621fc19208ab149a9c',s: '0x440ffd775ce91a833ab410777204d5341a6f9fa91216a6f3ee2c051fea6a0428',v: '0x25',rawTransaction: '0xf86a8086d55698372431831e848094f0109fc8df283027b6285cc889f5aa624eac1f55843b9aca008025a009ebb6ca057a0535d6186462bc0b465b561c94a295bdb0621fc19208ab149a9ca0440ffd775ce91a833ab410777204d5341a6f9fa91216a6f3ee2c051fea6a0428'
}

哈希一个消息

web3.eth.accounts.hashMessage(message);

web3.eth.accounts.hashMessage("Hello World")
> "0xa1de988600a42c4b4ab089b619297c17d53cffae5d5120d82d8a92d0bb3b78f2"// the below results in the same hash
web3.eth.accounts.hashMessage(web3.utils.utf8ToHex("Hello World"))
> "0xa1de988600a42c4b4ab089b619297c17d53cffae5d5120d82d8a92d0bb3b78f2"

sign 给任意一个内容使用私钥签名

web3.eth.accounts.sign(data, privateKey);

web3.eth.accounts.sign('Some data', '0x4c0883a69102937d6231471b5dbb6204fe5129617082792ae468d01a3f362318');
> {message: 'Some data',messageHash: '0x1da44b586eb0729ff70a73c326926f6ed5a25f5b056e7f47fbc6e58d86871655',v: '0x1c',r: '0xb91467e570a6466aa9e9876cbcd013baba02900b8979d43fe208a4a4f339f5fd',s: '0x6007e74cd82e037b800186422fc2da167c747ef045e5d18a5f5d4300f8e1a029',signature: '0xb91467e570a6466aa9e9876cbcd013baba02900b8979d43fe208a4a4f339f5fd6007e74cd82e037b800186422fc2da167c747ef045e5d18a5f5d4300f8e1a0291c'
}

使用web3.eth.personal 新建账户

web3.eth.personal.newAccount(password, [callback])

web3.eth.personal.newAccount('!@superpassword')
.then(console.log);
> '0x1234567891011121314151617181920212223456'

获得账户余额

web3.eth.getBalance('0xe70c4835b29e2fd35bd3f60c0a76413f70f17115').then(function(balance){console.log('balance:',balance)balance = new BigNumber(balance)console.log('balance:',balance)
})

这里使用了BigNumber.js 处理余额显示，参考我另一片博文。

utils工具函数

#####web3.utils.toHex 将任何值转为HEX 16进制
String|Number|Object|Array|BigNumber - 需要转化为HEX的值。如果是一个对象或数组类型，将会先用JSON.stringify1进行转换成字符串。如果传入的是BigNumber2，则将得到对应的Number的HEX

var str = "abcABC";
var obj = {abc: 'ABC'};
var bignumber = new BigNumber('12345678901234567890');var hstr = web3.utils.toHex(str);
var hobj = web3.utils.toHex(obj);
var hbg = web3.utils.toHex(bignumber);console.log("Hex of Sring:" + hstr);
console.log("Hex of Object:" + hobj);
console.log("Hex of BigNumber:" + hbg);

web3.utils.isHex(hex) 判断输入是不是16进制

web3.utils.isHex('0xc1912');

判断输入是不是一个地址

web3.utils.isAddress('0xc1912fee45d61c87cc5ea59dae31190fffff232d');

把金额单位换成wei

web3.utils.toWei(number [, unit])

web3.utils.toWei('1', 'ether');
> "1000000000000000000"web3.utils.toWei('1', 'finney');
> "1000000000000000"web3.utils.toWei('1', 'szabo');
> "1000000000000"web3.utils.toWei('1', 'shannon');
/> "1000000000"

把单位为wei的以太币换成 ether

web3.utils.fromWei(number [, unit])

web3.utils.fromWei('1', 'ether');
> "0.000000000000000001"web3.utils.fromWei('1', 'finney');
> "0.000000000000001"web3.utils.fromWei('1', 'szabo');
> "0.000000000001"web3.utils.fromWei('1', 'shannon');
> "0.000000001"

判断给定的数据是否是 BigNumber

web3.utils.isBigNumber(bignumber)

var number = new BigNumber(10);
web3.utils.isBigNumber(number);

sha3算法

// web3.utils.sha3(string)
// web3.utils.keccak256(string) // ALIAS

web3.utils.sha3('234'); // taken as string
> "0xc1912fee45d61c87cc5ea59dae311904cd86b84fee17cc96966216f811ce6a79"web3.utils.sha3(new BN('234'));
> "0xbc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a"web3.utils.sha3(234);
> null // can't calculate the has of a numberweb3.utils.sha3(0xea); // same as above, just the HEX representation of the number
> nullweb3.utils.sha3('0xea'); // will be converted to a byte array first, and then hashed
> "0x2f20677459120677484f7104c76deb6846a2c071f9b3152c103bb12cd54d1a4a"

[在github上获得代码] https://github.com/cooleye/web3tutorial

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