20181117--深入浅出区块链 智能合约开发环境搭建及Hello World合约

安装都完成了
geth --datadir “E:\blockchain\geth”testNet --dev console
启动textNet

eth.accouts
查看以太坊的账户

eth.getBalance(eth.accounts[0])
查看账户余额

personal.newAccount(“password”)
创建用户

给新账户转账
我们知道没有余额的账户是没法部署合约的，那我们就从默认账户转1以太币给新账户，使用以下命令（请使用你自己eth.accounts对应输出的账户）：

eth.sendTransaction({from: ‘0xf31498391f606b44934d4f6138d9c05799601b41’, to: ‘0x439cec3129137771b0210daa33e03cbf693608bb’, value: web3.toWei(1, “ether”)})

解锁账户
在部署合约前需要先解锁账户（就像银行转账要输入密码一样），使用以下命令：
personal.unlockAccount(eth.accounts[1],“password”)

编写合约代码

pragma solidity ^0.4.18;
contract hello {
    string greeting;
    
    function hello(string _greeting) public {
        greeting = _greeting;
    }

    function say() constant public returns (string) {
        return greeting;
    }
}

简单解释下，我们定义了一个名为hello的合约，在合约初始化时保存了一个字符串（我们会传入hello world），每次调用say返回字符串。
把这段代码写(拷贝)到Browser-Solidity，如果没有错误，点击Details获取部署代码，如：

var _greeting = hello world;
var helloContract = web3.eth.contract([{"constant":true,"inputs":[],"name":"say","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function","stateMutability":"view"},{"inputs":[{"name":"_greeting","type":"string"}],"payable":false,"type":"constructor","stateMutability":"nonpayable"}]);
var hello = helloContract.new(
   _greeting,
   {
     from: web3.eth.accounts[0], 
     data: '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', 
     gas: '4700000'
   }, function (e, contract){
    console.log(e, contract);
    if (typeof contract.address !== 'undefined') {
         console.log('Contract mined! address: ' + contract.address + ' transactionHash: ' + contract.transactionHash);
    }
 })

然后在geth的控制台输出

运行合约

> hello.say()
"Hello World"