以太坊私有链智能合约创建及调用

1.通过在线IDE并使用Solidity语言进行一个简单智能合约的编写与编译
https://chriseth.github.io/browser-solidity

pragma solidity ^0.4.18; 
 
contract helloworld { 
    uint data; 
 
    function set(uint x) { 
        data = x; 
    } 
    function get() constant returns (uint) { 
        return data; 
    }} 

2.选择版本

3.点击create复制web3 deploy

4.去除文件名，data添加0x前缀为16进制

var helloworldContract = web3.eth.contract([{"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}]); 
var helloworld = helloworldContract.new( 
   { 
     from: web3.eth.accounts[0],  
     data: '0x6060604052341561000f57600080fd5b60bb8061001d6000396000f30060606040526004361060485763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166360fe47b18114604d5780636d4ce63c146062575b600080fd5b3415605757600080fd5b60606004356084565b005b3415606c57600080fd5b60726089565b60405190815260200160405180910390f35b600055565b600054905600a165627a7a72305820cfa9843a61b33ba0a349c61e62924c94da4038579955f3771976f71874a2a97b0029',  
     gas: 3000000 
   }, function(e, contract){ 
    console.log(e, contract); 
    if (typeof contract.address != 'undefined') { 
         console.log('Contract mined! address: ' + contract.address + ' transactionHash: ' + contract.transactionHash); 
    } 
 }) 

7.粘贴到输入命令行

需要解锁账号再次执行

personal.unlockAccount("0x0bb81ec0920fed869f6b5f1bf46d4b923058af18","123456")//账号，密码 

成功
8.将合约写入区块链，挖矿成功关闭挖矿
9.调用合约set方法，需要花费费用，从0x0bb81ec0920fed869f6b5f1bf46d4b923058af18账户出费用，账户必须解除锁定，开启挖矿成功后停止挖矿

10.调用合约get（）方法

11.get（）方法不花费费用是因为constant关键字
constant说明此方法不会改变任何值、任何状态，因此也不会有任何花费