第12篇 web3.js - Ethereum JavaScript API（contract,部署与调用智能合约）

本文环境：

区块链：以太坊POA联盟链；

出块节点数：3；

操作系统：windows 64；

节点版本：Geth1.9.14；

node版本：v10.14.0

参考文档：https://web3js.readthedocs.io/en/v1.2.8/

2.6 transactionBlockTimeout

2.7 transactionConfirmationBlocks

2.8 transactionPollingTimeout

2.9 handleRevert

2.10 选项属性

2.11 options.address

2.12 options.jsonInterface

3.4 methods.myMethod.call

本文实例2：调用智能合约“常量”方法,不改变状态

3.5 methods.myMethod.send

本文实例3：调用智能合约方法,改变状态

3.6 methods.myMethod.estimateGas

本文实例4：估算智能合约方法gas用量

3.7 methods.myMethod.encodeABI

本文实例5：对智能合约方法进行 ABI 编码

web3.eth.Contract对象让你可以轻松地与以太坊区块链上的智能合约进行交互。当你创建一个新的合约对象时，只需要指定相应的智能合约 json 接口， web3 就会自动将所有的调用转换为基于 RPC 的底层 ABI 调用。

这使得你可以像 JavaScript 对象一样与智能合约进行交互。

一、new contract

new web3.eth.Contract(jsonInterface[, address][, options])

创建新的合约实例，并在其json interface对象中定义所有的方法和事件。

参数

jsonInterface - Object: 所要实例化合约的 json 接口
address - String （可选）: 要调用的智能合约地址
options - Object （可选）: 合约配置选项。其中某些选项被用作合约调用和交易的回调:

from - String: 交易发送方地址
gasPrice - String: 为交易指定的 gas 价格，以 wei 为单位
gas - Number: 交易可用的最大 gas 量（gas limit）。
data - String: 合约字节码。当合约被 :ref:`部署 <contract-deploy>`时需要使用。

返回值

Object: 带有所有方法和事件的合约实例

子

//官方示例
var myContract = new web3.eth.Contract([...], '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe', {
    from: '0x1234567890123456789012345678901234567891', // 默认交易发送地址
    gasPrice: '20000000000' // 以 wei 为单位的默认 gas 价格，当前价格为 20 gwei
});

二、属性

2.1 defaultAccount

web3.eth.Contract.defaultAccount
contract.defaultAccount // 合约实例上的默认账户

如果下面这些方法没有指定 "from" 属性，默认账户地址就会被用作默认的 "from" 属性：

web3.eth.sendTransaction()
web3.eth.call()
new web3.eth.Contract() -> myContract.methods.myMethod().call()
new web3.eth.Contract() -> myContract.methods.myMethod().send()

属性

String - 20 字节: 任意以太坊地址。你应该在你的节点或 keystore 中拥有该地址的私钥。 (默认值为 undefined)

例子

web3.eth.defaultAccount;
> undefined

// 设置默认账户
web3.eth.defaultAccount = '0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe';

2.2 defaultBlock

web3.eth.Contract.defaultBlock
contract.defaultBlock // 在合约实例上

默认块在一些特定方法上使用。你可以通过传入 defaultBlock 作为最后一个参数来覆盖它。默认值为 “latest”。

属性

默认块参数的可能取值如下：

Number|BN|BigNumber: 区块号
"genesis" - String: 创世块
"latest" - String: 最新块（也就是当前链头块）
"pending" - String: 正在挖的块（包括 pending 状态交易）
"earliest" - String: 创世块

默认值为 "latest"

例子

contract.defaultBlock;
> "latest"

// 设置默认块
contract.defaultBlock = 231;

2.3 defaultHardfork

contract.defaultHardfork

本地签名交易时用的默认硬分叉属性

属性

默认硬分叉属性的可能取值如下：

"chainstart" - String
"homestead" - String
"dao" - String
"tangerineWhistle" - String
"spuriousDragon" - String
"byzantium" - String
"constantinople" - String
"petersburg" - String
"istanbul" - String

默认值为 "petersburg"

例子

contract.defaultHardfork;
> "petersburg"

// 设置默认硬分叉
contract.defaultHardfork = 'istanbul';

2.4 defaultChain

contract.defaultChain

默认链属性是本地签名交易的时候用的

属性

默认链属性可以是一下列表中之一：

"mainnet" - String
"goerli" - String
"kovan" - String
"rinkeby" - String
"ropsten" - String

默认值为 "mainnet"

例子

contract.defaultChain;
> "mainnet"

// 设置默认链
contract.defaultChain = 'goerli';

2.5 defaultCommon

contract.defaultCommon

默认通用属性是本地签名交易的时候用的

属性

默认通用属性包含如下所示的 Common 对象：

customChain - Object: 自定义链属性

name - string: （可选）链名字
networkId - number: 自定义链的网络 Id
chainId - number: 自定义链的链 Id

baseChain - string: （可选） mainnet, goerli, kovan, rinkeby, or ropsten
hardfork - string: （可选） chainstart, homestead, dao, tangerineWhistle, spuriousDragon, byzantium, constantinople, petersburg, or istanbul

默认值为 undefined。

例子

contract.defaultCommon;
> {customChain: {name: 'custom-network', chainId: 1, networkId: 1}, baseChain: 'mainnet', hardfork: 'petersburg'}

// 设置默认通用值
contract.defaultCommon = {customChain: {name: 'custom-network', chainId: 1, networkId: 1}, baseChain: 'mainnet', hardfork: 'petersburg'};

2.6 transactionBlockTimeout

web3.eth.Contract.transcationBlockTimeout
contract.transactionBlockTimeout // 在合约实例上

transactionBlockTimeout 会被用在基于套接字的连接上。该属性定义了直到第一次确认发生它应该等待的区块数。这意味着当超时发生时，PromiEvent 会拒绝并显示超时错误。

返回值

number: transactionBlockTimeout 当前设定的值 (默认值: 50)

2.7 transactionConfirmationBlocks

web3.eth.Contract.transactionConfirmationBlocks
contract.transactionConfirmationBlocks // 在合约实例上

定义了确认交易所需要的区块确认数。

返回值

number: transactionConfirmationBlocks 当前设定的值 (默认值: 24)

2.8 transactionPollingTimeout

web3.eth.Contract.transactionPollingTimeout
contract.transactionPollingTimeout // 在合约实例上

transactionPollingTimeout 将通过 HTTP 连接使用。这个选项定义了 Web3 等待确认交易被网络挖出的收据的秒数。注意：当此种超时发生时，交易可能仍未完成。

返回值

number: transactionPollingTimeout 当前设定的值 (默认值: 750)

2.9 handleRevert

web3.eth.Contract.handleRevert
contract.handleRevert // 在合约实例上

handleRevert`选项属性默认值为`false，如果在 :ref:`send <contract-send>`或者 :ref:`call <contract-call>`合约方法时启用，将返回回退原因字符串。

注解

回退原因字符串和签名是存在于返回错误的属性中的。

返回值

boolean: handleRevert 的当前值 (默认值: false)

2.10 选项属性

myContract.options

合约实例的选项属性 对象。from、 gas 和 ``gasPrice``作为发送交易时的备用值使用。

属性

Object - 选项属性:

address - String: 合约的部署地址。
jsonInterface - Array: 合同的 json 接口。
data - String: 合约字节码。部署合约时使用。
from - String: 交易发起方地址。
gasPrice - String: 用于交易的 gas 价格。以 wei 为单位。
gas - Number: 可用于该交易的 gas 用量上限 (gas limit)。
handleRevert - Boolean: 如果这里不设置，将使用 Eth 模块提供的默认值。
transactionBlockTimeout - Number: 如果这里不设置，将使用 Eth 模块提供的默认值。
transactionConfirmationBlocks - Number: 如果这里不设置，将使用 Eth 模块提供的默认值。
transactionPollingTimeout - Number: 如果这里不设置，将使用 Eth 模块提供的默认值。
chain - Number: 如果这里不设置，将使用 Eth 模块提供的默认值。
hardfork - Number: 如果这里不设置，将使用 Eth 模块提供的默认值。
common - Number: 如果这里不设置，将使用 Eth 模块提供的默认值。

例子

myContract.options;
> {
    address: '0x1234567890123456789012345678901234567891',
    jsonInterface: [...],
    from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
    gasPrice: '10000000000000',
    gas: 1000000
}

myContract.options.from = '0x1234567890123456789012345678901234567891'; // 默认交易发送方地址
myContract.options.gasPrice = '20000000000000'; // 默认 gas 价格，以 wei 为单位
myContract.options.gas = 5000000; // 5M gas 作为备用值

2.11 options.address

myContract.options.address

用于本合约实例的地址。所有通过 web3.js 从这个合约生成的交易都将包含这个地址作为 “to” 地址（也就是交易接收方地址）。

地址将以小写的方式保存。

属性

address - String|null: 本合约的地址, 如果未设置其值为 null。

例子

myContract.options.address;
> '0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae'

// 设置新地址
myContract.options.address = '0x1234FFDD...';

2.12 options.jsonInterface

myContract.options.jsonInterface

从合约的ABI派生出来的json接口对象。

属性

jsonInterface - Array: 当前合约的json接口。重设该接口会导致合约实例方法和事件的重新生成。

例子

myContract.options.jsonInterface;
> [{
    "type":"function",
    "name":"foo",
    "inputs": [{"name":"a","type":"uint256"}],
    "outputs": [{"name":"b","type":"address"}]
},{
    "type":"event",
    "name":"Event",
    "inputs": [{"name":"a","type":"uint256","indexed":true},{"name":"b","type":"bytes32","indexed":false}],
}]

// 设置新的接口
myContract.options.jsonInterface = [...];

三、方法

3.1 clone

myContract.clone()

克隆当前合约实例。

例子

var contract1 = new eth.Contract(abi, address, {gasPrice: '12345678', from: fromAddress});

var contract2 = contract1.clone();
contract2.options.address = address2;

(contract1.options.address !== contract2.options.address);
> true

3.2 deploy

myContract.deploy(options)

调用此函数将合约部署到区块链上。成功部署后 promise 对象会被解析为新的合约实例。

参数

options - Object: 用于合约部署的选项。

data - String: 合约字节码
arguments - Array （可选）: 在部署合约时传递给构造函数的参数。

返回值

Object: 交易对象：

Array - 参数: 之前传递给方法的参数。它们是可以被改变的。
Function - send: 用来部署合约。promise 会被解析为合约实例而不是交易收据。
Function - estimateGas: 估算部署合约所需要的 gas 用量。
Function - encodeABI: 编码由合约数据和构造函数参数构成的合约部署 ABI。

关于这些方法的更多详情，参见下面的文档。

例子

myContract.deploy({
    data: '0x12345...',
    arguments: [123, 'My String']
})
.send({
    from: '0x1234567890123456789012345678901234567891',
    gas: 1500000,
    gasPrice: '30000000000000'
}, function(error, transactionHash){ ... })
.on('error', function(error){ ... })
.on('transactionHash', function(transactionHash){ ... })
.on('receipt', function(receipt){
   console.log(receipt.contractAddress) // 包含新合约地址
})
.on('confirmation', function(confirmationNumber, receipt){ ... })
.then(function(newContractInstance){
    console.log(newContractInstance.options.address) // 带有新合约地址的合约实例
});


//数据已经设置为合约本身的选项
myContract.options.data = '0x12345...';

myContract.deploy({
    arguments: [123, 'My String']
})
.send({
    from: '0x1234567890123456789012345678901234567891',
    gas: 1500000,
    gasPrice: '30000000000000'
})
.then(function(newContractInstance){
    console.log(newContractInstance.options.address) // 具有新合同地址的合约实例
});


// 只是编码
myContract.deploy({
    data: '0x12345...',
    arguments: [123, 'My String']
})
.encodeABI();
> '0x12345...0000012345678765432'


// gas 估算
myContract.deploy({
    data: '0x12345...',
    arguments: [123, 'My String']
})
.estimateGas(function(err, gas){
    console.log(gas);
});

本文实例1：使用代码部署智能合约

//本文示例，实际部署了一个erc20合约，用于本文测试
var Web3= require('web3');   
var web3= new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

var initialAmount = 1000000;               /* var of type uint256 here */ 
var tokenName =  "kongfuziToken";          /* var of type string here */
var decimalUnits =  18;                    /* var of type uint8 here */
var tokenSymbol =  "KFZT";                 /* var of type string here */

var tokentestContract =  new web3.eth.Contract([{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"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":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"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"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","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"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[{"name":"initialAmount","type":"uint256"},{"name":"tokenName","type":"string"},{"name":"decimalUnits","type":"uint8"},{"name":"tokenSymbol","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"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"},{"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"}]);

var tokentest = tokentestContract.deploy({
     data: 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
     arguments: [initialAmount, tokenName, decimalUnits, tokenSymbol]
})
   .send({
     from: "0x38D8B866a1ABeBcA20AFC004622F5355EeFEB568", 
     gas: '5700000'
   }, function(error, transactionHash){
	 console.log(error, transactionHash)
   })
   .on('receipt', function(receipt){
     console.log("receipt.contractAddress :" + receipt.contractAddress); // 包含新合约地址
     console.log(receipt)
   })
   .then(function(newContractInstance){
     console.log("newContractInstance.options.address :" + newContractInstance.options.address) // 带有新合约地址的合约实例
   });

/*
null '0xa63dd8dc8b3b1de2f7e1276a92dc71665684660b3f97d2d6a299659de2f88b6f'
receipt.contractAddress :0xb43938511C10A242dce4f5C110c54fBB51f5bd28
{ blockHash:
   '0x7f8d2898026aa7a0665f6460becc930c1a2afc55e5b323b5013c114eb3a6c14d',
  blockNumber: 278509,
  contractAddress: '0xb43938511C10A242dce4f5C110c54fBB51f5bd28',
  cumulativeGasUsed: 1114009,
  from: '0x38d8b866a1abebca20afc004622f5355eefeb568',
  gasUsed: 1114009,
  logsBloom:
   '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000040000000000008000000000000000000000000000000000000000000000000020000000000000000000800000000000000000000000010000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000000000000200000042000000000000000000000000000000000000000000000000000420000010000000000000000000000000000000000000000000000000000000000000',
  status: true,
  to: null,
  transactionHash:
   '0xa63dd8dc8b3b1de2f7e1276a92dc71665684660b3f97d2d6a299659de2f88b6f',
  transactionIndex: 0,
  events:
   { Transfer:
      { address: '0xb43938511C10A242dce4f5C110c54fBB51f5bd28',
        blockNumber: 278509,
        transactionHash:
         '0xa63dd8dc8b3b1de2f7e1276a92dc71665684660b3f97d2d6a299659de2f88b6f',
        transactionIndex: 0,
        blockHash:
         '0x7f8d2898026aa7a0665f6460becc930c1a2afc55e5b323b5013c114eb3a6c14d',
        logIndex: 0,
        removed: false,
        id: 'log_d01b6181',
        returnValues: [Result],
        event: 'Transfer',
        signature:
         '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
        raw: [Object] } } }
newContractInstance.options.address :0xb43938511C10A242dce4f5C110c54fBB51f5bd28
*/

注意：

不同版本web3.js带来的API变化问题。请检查你的web3.js版本：

如果version<1.0.0，使用：

new web3.eth.contract(studentFactoryArtifact,address);     // 注意区分contract大小写

如果version>1.0.0，使用：

new web3.eth.Contract(studentFactoryArtifact,address);     // 注意区分Contract大小写

3.3 methods

myContract.methods.myMethod([param1[, param2[, ...]]])

为指定方法创建一个交易对象, 可以被用来 called, send, estimated.

该智能合约的方法可以通过下面几种方式得到:

方法名: myContract.methods.myMethod(123)
带参数的方法名: myContract.methods['myMethod(uint256)'](123)
方法签名: myContract.methods['0x58cf5f10'](123)

这样可以调用与 JavaScript 合约对象名称相同但参数不同的函数。

返回值

Object: 交易对象:

Array - 参数: 之前传递给方法的参数。它们是可以被改变的。
Function - call: 将在不发送交易的情况下调用该“常量”方法并在 EVM 中执行其智能合约方法（无法更改智能合约状态）。
Function - send: 用来向合约发送交易并执行其方法（可以更改智能合约状态）。
Function - estimateGas: 将估算在链上执行该方法时所要消耗的 gas。
Function - encodeABI: 对合于方法进行 ABI 编码。得到的编码可以通过交易去 send，可以直接 call，也可以作为参数传给另外一个智能合约方法。

关于这些方法的更多详情，参见下面的文档。

例子

// 对一个方法发起 call 调用

myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result){
    ...
});

// 或者发生交易并使用 promise
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt){
    // receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
});

// 或者发送交易并使用事件
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.on('transactionHash', function(hash){
    ...
})
.on('receipt', function(receipt){
    ...
})
.on('confirmation', function(confirmationNumber, receipt){
    ...
})
.on('error', function(error, receipt) {
    ...
});

3.4 methods.myMethod.call

myContract.methods.myMethod([param1[, param2[, ...]]]).call(options[, callback])

将在不发送交易的情况下调用该“常量”方法并在 EVM 中执行其智能合约方法。注意此种调用方式无法改变智能合约状态。

参数

options - Object （可选）: 用于发起调用的选项。

from - String （可选）: 调用“交易”的发起方地址。
gasPrice - String （可选）: 用于该调用“交易”的 gas 价格。以 wei 为计量单位。
gas - Number （可选）: 用于该调用“交易”的 gas 用量上限 (gas limit)。

callback - Function （可选）: 回调函数，回调时将以智能合约方法执行结果作为第二个参数，以错误对象作为第一个参数。

返回值

Promise 返回 Mixed: 智能合约方法返回值。如果只返回一个值，则按原样返回。如果有多个返回值，则作为一个带有属性和索引的对象返回。

例子

// 使用回调
myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result){
    ...
});

// 使用 promise
myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(result){
    ...
});


// 多返回值:

// Solidity
contract MyContract {
    function myFunction() returns(uint256 myNumber, string myString) {
        return (23456, "Hello!%");
    }
}

// web3.js
var MyContract = new web3.eth.Contract(abi, address);
MyContract.methods.myFunction().call()
.then(console.log);
> Result {
    myNumber: '23456',
    myString: 'Hello!%',
    0: '23456', // 这里这些是作为属性名称时的备用值
    1: 'Hello!%'
}


// 单参数返回:

// Solidity
contract MyContract {
    function myFunction() returns(string myString) {
        return "Hello!%";
    }
}

// web3.js
var MyContract = new web3.eth.Contract(abi, address);
MyContract.methods.myFunction().call()
.then(console.log);
> "Hello!%"

本文实例2：调用智能合约“常量”方法,不改变状态

var Web3= require('web3');   
var web3= new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

var contractAddress = "0xb43938511C10A242dce4f5C110c54fBB51f5bd28";   //智能合约地址
var accountsAddress = "0x38D8B866a1ABeBcA20AFC004622F5355EeFEB568";
var contractAbi = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"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":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"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"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","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"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[{"name":"initialAmount","type":"uint256"},{"name":"tokenName","type":"string"},{"name":"decimalUnits","type":"uint8"},{"name":"tokenSymbol","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"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"},{"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"}];
var myContract =  new web3.eth.Contract(contractAbi,contractAddress);

	
    myContract.methods.totalSupply().call().then(function(result){
        console.log("totalSupply:",result);
    });
	
    myContract.methods.name().call().then(function(result){
        console.log("name:",result);
    });
	
    myContract.methods.decimals().call().then(function(result){
        console.log("decimals:",result);
    });
	
    myContract.methods.symbol().call().then(function(result){
        console.log("symbol:",result);
    });
	
    myContract.methods.owner().call().then(function(result){
        console.log("owner:",result);
    });
	
    myContract.methods.balanceOf(accountsAddress).call().then(function(result){
        console.log("result1:",result);
        console.log("result2:",JSON.stringify(result));
    });

/*
totalSupply: 1000000000000000000000000
decimals: 18
name: kongfuziToken
symbol: KFZT
owner: 0x38D8B866a1ABeBcA20AFC004622F5355EeFEB568
result1: 1000000000000000000000000
result2: "1000000000000000000000000"
*/

3.5 methods.myMethod.send

myContract.methods.myMethod([param1[, param2[, ...]]]).send(options[, callback])

向合约发送交易来执行其方法。注意这会改变合约状态。

参数

options - Object: 用来发送交易的选项。

from - String: 交易发送方地址。
gasPrice - String （可选）: 用于该交易的 gas 价格，以 wei 为单位。
gas - Number （可选）: 该交易 gas 用量上限 (gas limit)。
value - ``Number|String|BN|BigNumber``（可选）: 交易转账金额，以 wei 为单位。

callback - Function （可选）: 回调函数，触发时其第二个参数为交易哈希，第一个参数为错误对象。

返回值

回调将返回 32 字节的交易哈希值。

PromiEvent: 一个整合了事件发生器 <promiEvent> promise. 当收到交易*收据*时会被解析, 当该``send()``调用是从``someContract.deploy()``发出时，promise 会解析为*新合约地址*。重设该接口会导致合约实例方法和事件的重新生成。此外也存在下面这些事件:

"transactionHash" 返回 String: 发送交易且得到交易哈希值后立即触发。
"receipt" 返回 Object: 当收到交易*收据*时触发。合约收据带有的不是``logs``，而是以事件名称为健，以事件本身为属性值的``events``。关于返回事件对象的详情，参见 getPastEvents 返回值。
"confirmation" 返回 Number, Object: 从区块被挖到的第一个区块确认开始，每次确认都会触发，直到第 24 次确认。触发时第一个参数为收到的确认数，第二个参数为收到交易收据。
"error" 返回 Error 和 Object|undefined: 交易发送过程中出错时触发。如果交易被网络拒绝且带有交易收据，第二个参数就是该交易收据。

例子

// 使用回调
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, transactionHash){
    ...
});

// 使用 promise
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt){
    // 当这个 receipt 对象来自于 "contract.deploy({...}).send()" 这么个调用时，它也可以是一个新合约实例
});


// 使用事件触发器
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.on('transactionHash', function(hash){
    ...
})
.on('confirmation', function(confirmationNumber, receipt){
    ...
})
.on('receipt', function(receipt){
    // receipt 相关例子
    console.log(receipt);
    > {
        "transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
        "transactionIndex": 0,
        "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
        "blockNumber": 3,
        "contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
        "cumulativeGasUsed": 314159,
        "gasUsed": 30234,
        "events": {
            "MyEvent": {
                returnValues: {
                    myIndexedParam: 20,
                    myOtherIndexedParam: '0x123456789...',
                    myNonIndexParam: 'My String'
                },
                raw: {
                    data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                    topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                },
                event: 'MyEvent',
                signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                logIndex: 0,
                transactionIndex: 0,
                transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                blockNumber: 1234,
                address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
            },
            "MyOtherEvent": {
                ...
            },
            "MyMultipleEvent":[{...}, {...}] // 如果同一事件有多个，则它们将被组装到数组中
        }
    }
})
.on('error', function(error, receipt) { // 如果交易被网络拒绝并带有交易收据，则第二个参数将是交易收据。
    ...
});

本文实例3：调用智能合约方法,改变状态

var Web3= require('web3');   
var web3= new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

var contractAddress = "0xb43938511C10A242dce4f5C110c54fBB51f5bd28";   //智能合约地址
var accountsAddress = "0x38D8B866a1ABeBcA20AFC004622F5355EeFEB568";
var contractAbi = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"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":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"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"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","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"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[{"name":"initialAmount","type":"uint256"},{"name":"tokenName","type":"string"},{"name":"decimalUnits","type":"uint8"},{"name":"tokenSymbol","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"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"},{"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"}];
var myContract =  new web3.eth.Contract(contractAbi,contractAddress);
	
    // 使用promise
    // personal.unlockAccount(eth.accounts[1],password,0)
    var toAddress = "0xDa25997b15a6BeA86116942B8Ab69a5620D82284";
    myContract.methods.transfer(toAddress,1230000000000).send({from: accountsAddress})
    .then(function(receipt){
		console.log("receipt:",receipt);
    });

/*
receipt: { blockHash:
   '0xbec129bb90df90619a19a064826d7baab7d84fd2f4c58a7a767d2e858c5b0c15',
  blockNumber: 301107,
  contractAddress: null,
  cumulativeGasUsed: 54019,
  from: '0x38d8b866a1abebca20afc004622f5355eefeb568',
  gasUsed: 54019,
  logsBloom:
   '0x00000000000000000010000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000040000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000200000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000000000000200000042000000000000000000000000000000000000000000000000000400000010000000000000000000000000000000000000000000000000000000000000',
  status: true,
  to: '0xb43938511c10a242dce4f5c110c54fbb51f5bd28',
  transactionHash:
   '0x5f8850cbc8c21b7b10917777a4c9ebd5cbb0a2e5370d108edb767d0ca44576f1',
  transactionIndex: 0,
  events:
   { Transfer:
      { address: '0xb43938511C10A242dce4f5C110c54fBB51f5bd28',
        blockNumber: 301107,
        transactionHash:
         '0x5f8850cbc8c21b7b10917777a4c9ebd5cbb0a2e5370d108edb767d0ca44576f1',
        transactionIndex: 0,
        blockHash:
         '0xbec129bb90df90619a19a064826d7baab7d84fd2f4c58a7a767d2e858c5b0c15',
        logIndex: 0,
        removed: false,
        id: 'log_d82a25b4',
        returnValues: [Result],
        event: 'Transfer',
        signature:
         '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
        raw: [Object] } } }
*/

3.6 methods.myMethod.estimateGas

myContract.methods.myMethod([param1[, param2[, ...]]]).estimateGas(options[, callback])

通过在 EVM 中执行方法来估算链上执行是需要的 gas 用量。由于彼时合约状态的不同，当前估算的 gas 用量和随后通过真实交易所得到的实际 gas 用量可能会有所出入。

参数

options - Object （可选）: 用于调用的选项。

from - String （可选）: 交易发起方地址。
gas - Number （可选）: 交易 gas 用量上限 (gas limit)。设置特定的值有助于检测 gas 耗尽相关错误，gas 耗尽时会返回相同的值。
value - ``Number|String|BN|BigNumber``（可选）: 交易转账金额，以 wei 为单位。

callback - Function （可选）: 回调函数，触发时其第二个参数为 gas 估算量，第一个参数为错误对象。

返回值

Promise 返回 Number: 估算的 gas 用量

例子

// 使用回调
myContract.methods.myMethod(123).estimateGas({gas: 5000000}, function(error, gasAmount){
    if(gasAmount == 5000000)
        console.log('Method ran out of gas');
});

// 使用 promise
myContract.methods.myMethod(123).estimateGas({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(gasAmount){
    ...
})
.catch(function(error){
    ...
});

本文实例4：估算智能合约方法gas用量

var Web3= require('web3');   
var web3= new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

var contractAddress = "0xb43938511C10A242dce4f5C110c54fBB51f5bd28";   //智能合约地址
var accountsAddress = "0x38D8B866a1ABeBcA20AFC004622F5355EeFEB568";
var contractAbi = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"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":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"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"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","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"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[{"name":"initialAmount","type":"uint256"},{"name":"tokenName","type":"string"},{"name":"decimalUnits","type":"uint8"},{"name":"tokenSymbol","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"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"},{"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"}];
var myContract =  new web3.eth.Contract(contractAbi,contractAddress);
var toAddress = "0xDa25997b15a6BeA86116942B8Ab69a5620D82284";

    // 使用 promise
    // personal.unlockAccount(eth.accounts[1],password,0)
    myContract.methods.transfer(toAddress,1230000000000).estimateGas({from: accountsAddress})
    .then(function(gasAmount){
	console.log("gasAmount:",gasAmount);
    })
    .catch(function(error){
	console.log("error:",error);
    });

/*
gasAmount: 39019
*/

3.7 methods.myMethod.encodeABI

myContract.methods.myMethod([param1[, param2[, ...]]]).encodeABI()

为指定的合约方法进行 ABI 编码，可用于发送交易、调用方法或向另一个合约方法传递参数。

返回值

String: 编码后的 ABI 字节码，可用于交易发送或方法调用。

例子

myContract.methods.myMethod(123).encodeABI();
> '0x58cf5f1000000000000000000000000000000000000000000000000000000000000007B'

本文实例5：对智能合约方法进行 ABI 编码

var Web3= require('web3');   
var web3= new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

var contractAddress = "0xb43938511C10A242dce4f5C110c54fBB51f5bd28";   //智能合约地址
var accountsAddress = "0x38D8B866a1ABeBcA20AFC004622F5355EeFEB568";
var contractAbi = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"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":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"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"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","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"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[{"name":"initialAmount","type":"uint256"},{"name":"tokenName","type":"string"},{"name":"decimalUnits","type":"uint8"},{"name":"tokenSymbol","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"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"},{"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"}];
var myContract =  new web3.eth.Contract(contractAbi,contractAddress);
var toAddress = "0xDa25997b15a6BeA86116942B8Ab69a5620D82284";

    console.log(myContract.methods.transfer(toAddress,1230000000000).encodeABI());

/*
0xa9059cbb000000000000000000000000da25997b15a6bea86116942b8ab69a5620d822840000000000000000000000000000000000000000000000000000011e61b68c00
*/

四、事件

4.1 once

myContract.once(event[, options], callback)

订阅一个事件并在第一次事件触发或错误发生后立即取消订阅。一个事件仅触发一次。

参数

event - String: 要订阅的合约事件名, 或者用 "allEvents" 来订阅所有事件。
options - Object （可选）: 用于部署的选项。

filter - Object （可选）: 按索引参数过滤事件, 例如 {filter: {myNumber: [12,13]}} 表示 “myNumber” 为 12 或 13 的所有事件。
topics - Array （可选）: 手动设置事件过滤器的主题。如果提供了过滤器属性和事件签名，则不会自动设置（topic [0]）

callback - Function: 回调函数，触发时把*事件*对象作为第二个参数，错误作为第一个参数。关于详细事件结构，参见 getPastEvents 返回值。

例子

myContract.once('MyEvent', {
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // 使用数组表示 或：比如 20 或 23。
    fromBlock: 0
}, function(error, event){ console.log(event); });

// 事件输入的例子
> {
    returnValues: {
        myIndexedParam: 20,
        myOtherIndexedParam: '0x123456789...',
        myNonIndexParam: 'My String'
    },
    raw: {
        data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
        topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
    },
    event: 'MyEvent',
    signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    logIndex: 0,
    transactionIndex: 0,
    transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
    blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    blockNumber: 1234,
    address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
}

4.2 events

myContract.events.MyEvent([options][, callback])

订阅指定的合约事件

参数

options - Object （可选）: 用于部署的选项。

filter - Object （可选）: 按索引参数过滤事件, 例如 {filter: {myNumber: [12,13]}} 表示 “myNumber” 为 12 或 13 的所有事件。
fromBlock - Number|String|BN|BigNumber （可选）: 读取从该编号开始的区块中的事件（大于或等于该区块号）。也可以使用预先定义的区块号，比如 "latest", "earlist", "pending", "genesis" 等。
topics - Array （可选）: 手动设置事件过滤器的主题。如果提供了过滤器属性和事件签名，则不会自动设置（topic [0]）。

callback - Function （可选）: 回调函数，触发时把*事件*对象作为第二个参数，错误作为第一个参数。

返回值

EventEmitter: 该事件发生器有以下事件：

"data" 返回 Object: 接收到新传入的事件时触发，参数为事件对象。
"changed" 返回 Object: 当事件从区块链上移除时触发。该事件带有额外属性 "removed: true"。
"error" 返回 Object: 当订阅中出现错误时触发。
"connected" 返回 String: 当订阅成功连接时触发一次。返回订阅 id。

返回的事件 “对象” 结构如下：

event - String: 事件名称。
signature - String|Null: 事件签名，如果是匿名事件，其值为 null。
address - String: 该事件的发源地地址。
returnValues - Object: 事件返回值，比如 {myVar: 1, myVar2: '0x234...'}.
logIndex - Number: 事件在区块中的索引位置。
transactionIndex - Number: 事件所在交易在区块中的索引位置。
transactionHash 32 Bytes - String: 事件所在交易的哈希值。
blockHash 32 Bytes - String: 事件所在区块链的哈希值。区块处于 pending 状态时其值为 null 。
blockNumber - Number: 事件所在区块的区块号。区块处于 pending 状态时其值为 null 。
raw.data - String: 包含未索引的日志参数。
raw.topics - Array: 最大可保存 4 个 32 字节长的主题数组，主题 1-3 包含事件的索引参数。

例子

myContract.events.MyEvent({
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // 使用数组表示 或：如 20 或 23。
    fromBlock: 0
}, function(error, event){ console.log(event); })
.on("connected", function(subscriptionId){
    console.log(subscriptionId);
})
.on('data', function(event){
    console.log(event); // 与上述可选的回调结果相同
})
.on('changed', function(event){
    // 从本地数据库中删除事件
})
.on('error', function(error, receipt) { // 如果交易被网络拒绝并带有交易收据，第二个参数将是交易收据。
    ...
});

// 事件输出例子
> {
    returnValues: {
        myIndexedParam: 20,
        myOtherIndexedParam: '0x123456789...',
        myNonIndexParam: 'My String'
    },
    raw: {
        data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
        topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
    },
    event: 'MyEvent',
    signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    logIndex: 0,
    transactionIndex: 0,
    transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
    blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    blockNumber: 1234,
    address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
}

4.3 events.allEvents

myContract.events.allEvents([options][, callback])

和事件相同，只是会接收合约的所有事件。过滤属性可以选择性地过滤这些事件。

4.4 getPastEvents

myContract.getPastEvents(event[, options][, callback])

读取合约历史事件。

参数

event - String: 合约事件名，或者用 "allEvents" 读取所有事件。
options - Object （可选）: 用于部署的选项。

filter - Object （可选）: 按索引参数过滤事件, 例如 {filter: {myNumber: [12,13]}} 表示 “myNumber” 为 12 或 13 的所有事件。
fromBlock - Number|String|BN|BigNumber （可选）: 读取从该编号开始的区块中的历史事件（大于或等于该区块号）。也可以使用预先定义的区块编号，比如 "latest", "earlist", "pending", "genesis" 。
toBlock - Number|String|BN|BigNumber （可选）: 读取截止到该编号的区块中的历史事件（小于或等于该区块号）（默认值为 “latest”）。也可以使用预先定义的区块编号，比如 "latest", "earlist", "pending", "genesis" 。
topics - Array （可选）: 用来手动设置事件过滤器的主题。如果设置了 filter 属性和事件签名，则不会自动设置（topic [0]）。

callback - Function （可选）: 回调函数，触发时其第一个参数为错误对象，第二个参数为历史事件日志数组。

返回值

Promise 返回 Array: 满足给定事件或过滤条件的历史事件对象数组。
对于返回的事件对象结构，参见 getPastEvents 返回值。

例子

myContract.getPastEvents('MyEvent', {
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // 使用数组表示 或：如 20 或 23。
    fromBlock: 0,
    toBlock: 'latest'
}, function(error, events){ console.log(events); })
.then(function(events){
    console.log(events) // 与上述可选回调结果相同
});

> [{
    returnValues: {
        myIndexedParam: 20,
        myOtherIndexedParam: '0x123456789...',
        myNonIndexParam: 'My String'
    },
    raw: {
        data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
        topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
    },
    event: 'MyEvent',
    signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    logIndex: 0,
    transactionIndex: 0,
    transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
    blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    blockNumber: 1234,
    address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
},{
    ...
}]

四、本文智能合约源码

请注意：本合约仅用于测试。

pragma solidity ^0.4.18;

/**
 * Math operations with safety checks
 */
contract SafeMath {
    function safeMul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    require(c / a == b);
    return c;
    }
 
    function safeDiv(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0);
    uint256 c = a / b;
    require(a == b * c + a % b);
    return c;
    }
 
    function safeSub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    return a - b;
    }
 
    function safeAdd(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c>=a && c>=b);
    return c;
    } 
}

contract Token is SafeMath{

    function balanceOf(address _owner) public constant returns (uint256 balance);
	
    function transfer(address _to, uint256 _value) public returns (bool success);
	
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);

    function approve(address _spender, uint256 _value) public returns (bool success);

    function allowance(address _owner, address _spender) public constant returns (uint256 remaining);

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
	
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

contract TokenTEST is Token {
    uint256 public totalSupply;				
    string  public name;                   	
    uint8   public decimals;               
    string  public symbol;               	
    address public owner;                   
	
    /* This creates an array with all balances */
    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;

    function TokenTEST(uint256 initialAmount, string tokenName, uint8 decimalUnits, string tokenSymbol) public {
        totalSupply = SafeMath.safeMul(initialAmount , 10 ** uint256(decimalUnits));  
        balances[msg.sender] = totalSupply; 						
        Transfer(address(0), msg.sender, totalSupply);                         
		 
        name = tokenName;                   
        decimals = decimalUnits;          
        symbol = tokenSymbol;
        owner = msg.sender;
    }

    /* Send tokens */
    function transfer(address _to, uint256 _value) public returns (bool success) {
    	require(_to != address(0));
    	require(_to != msg.sender);
    	require(_value >= 0);
    	require(balances[msg.sender] >= _value);
    	require(balances[_to] + _value >= balances[_to]);
        
        balances[msg.sender] = SafeMath.safeSub(balances[msg.sender], _value);   // Subtract from the sender
        balances[_to] = SafeMath.safeAdd(balances[_to], _value);                 
        Transfer(msg.sender, _to, _value);		                                 
        return true;
    }

    /* A contract attempts to get the tokens */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_to != address(0));
        require(_to != _from);
        require(_value >= 0);
        require(_value <= balances[_from]);                  // Check if the sender has enough
        require(_value <= allowed[_from][msg.sender]);       // Check allowance
        require(balances[_to] + _value >= balances[_to]);    // Check for overflows
		
        balances[_from] = SafeMath.safeSub(balances[_from], _value);                           // Subtract from the sender
        balances[_to] = SafeMath.safeAdd(balances[_to], _value);    // Add the same to the recipient
        allowed[_from][msg.sender] = SafeMath.safeSub(allowed[_from][msg.sender], _value);
        Transfer(_from, _to, _value);			             
        return true;
    }
	
    function balanceOf(address _owner) public constant returns (uint256 balance) {
        return balances[_owner];
    }

    /* Allow another contract to spend some tokens in your behalf */	
    function approve(address _spender, uint256 _value) public returns (bool success) { 
        //require((_value == 0) || (allowed[msg.sender][_spender] == 0)); 
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
        return allowed[_owner][_spender];		
    }
	
    // only owner can kill
    function kill() { 
        require(msg.sender == owner);
        selfdestruct(owner);             
    }

}