第3章 编写智能合约

1. 开发者模式，启动挖矿

geth --dev --mine

会输出

INFO [03-19|16:42:08] IPC endpoint opened                      url=/var/folders/mj/mkwhd7897qn3ml_mc_tp0_700000gn/T/geth.ipc

2. 新开一个窗口，打开交互console

geth attach  --datadir "/var/folders/mj/mkwhd7897qn3ml_mc_tp0_700000gn/T"

不指定datadir可能会出错，目录根据上一步的提示填写

3. 以下代码拷贝粘贴到在线浏览器页面，并编译成web3.js代码

contract Proof
{
    struct FileDetails
    {
        uint timestamp;
        string owner;
    }

    mapping (string => FileDetails) files;

    event logFileAddedStatus(bool status, uint timestamp, string owner, string fileHash);

    function set (string owner, string fileHash)
    {
        if(files[fileHash].timestamp == 0)
        {
            files[fileHash] = FileDetails(block.timestamp, owner);
            logFileAddedStatus(true, block.timestamp, owner, fileHash);
        }
        else
        {
            logFileAddedStatus(false, block.timestamp, owner, fileHash);
        }
    }

    function get(string fileHash) returns (uint timestamp, string owner)
    {
        return (files[fileHash].timestamp, files[fileHash].owner);
    }
}

生成的web3.js代码如下

var proofContract = web3.eth.contract([{"constant":false,"inputs":[{"name":"fileHash","type":"string"}],"name":"get","outputs":[{"name":"timestamp","type":"uint256"},{"name":"owner","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"owner","type":"string"},{"name":"fileHash","type":"string"}],"name":"set","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"anonymous":false,"inputs":[{"indexed":false,"name":"status","type":"bool"},{"indexed":false,"name":"timestamp","type":"uint256"},{"indexed":false,"name":"owner","type":"string"},{"indexed":false,"name":"fileHash","type":"string"}],"name":"logFileAddedStatus","type":"event"}]);
var proof = proofContract.new(
   {
     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);
    }
 })

4. 拷贝到交互控制台，可得到类似如下的代码输出（合约地址）

Contract mined! address: 0xf095b1932ee9e6424b328bdf518d617503c7c0f7 transactionHash: 0x3fc10b7326cc5f4211ac6c665c3370b2d00a1b433659cfb1e48da8d0b884ae01

5. 验证合约，存入一个hash

var contract_obj = proofContract.at("0xf095b1932ee9e6424b328bdf518d617503c7c0f7");
contract_obj.set.sendTransaction("Owner Name", "0x1628cb0fE5e3fFE930C4Fb13Ba3C0d032DD6cadE",{from: web3.eth.accounts[0],},function(error, transactionHash) {
    if (!err)
        console.log(transactionHash);
})

正常情况下无输出。
以下代码返回时间戳

contract_obj.get.call("0x1628cb0fE5e3fFE930C4Fb13Ba3C0d032DD6cadE");

[1521451376, "Owner Name"]

这个时间戳是 2018-03-19 17:22:56，也就是刚才。