以太坊（三）MAC以太坊私有链创建第一个智能合约

清疚 2022-05-27 01:36 626阅读 0赞

转载自：https://www.jianshu.com/p/d699c82cedde

前天搭建了以太坊的私有链环境，今天本来想建立一个基于以太坊的智能合约Demo，发现很多过去的文档都已经过时了（包括github官网），折腾了半天，终于搞定了，现记录如下。

--------------------

## 安装智能合约编译器 ##

brew tap ethereum/ethereum
    brew install solidity

## 创建智能合约 ##

#### 新建一个contract文件夹，在文件夹中创建一个demo.sol智能合约文件 ####

pragma solidity ^0.4.20;
    contract Demo {
      function print(string str) returns (string content) {
        content = str;
      }
    }

#### 编译，会多出两个文件，abi文件就是智能合约相关的接口，bin文件就是智能合约编译代码。 ####

> solc -o . --bin --abi demo.sol
    > ls
    Demo.abi    Demo.bin    demo.sol

#### 在geth中加载这些文件很复杂，这里我们修改下刚生成的文件 ####

Demo.abi 文件内容修改成

var demoContract = eth.contract([{
         "constant":false,"inputs":[{
         "name":"str","type":"string"}],"name":"print","outputs":[{
         "name":"content","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"function"}])

Demo.bin 文件内容修改成

personal.unlockAccount(eth.accounts[0])
    var demo = demoContract.new({
      from: eth.accounts[0],
      data: "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",
      gas: 500000
    })

> 注意：别忘了data必须0x开头，New合约就得解锁自己的账户，这里解锁也写在这里了

#### 回到geth，加载刚修改的文件，加载bin文件需要输入账户密码 ####

> 文件夹contract就运行在geth命令的目录

> loadScript("contract/Demo.abi")
    true
    > loadScript("contract/Demo.bin")
    Unlock account 0x0416f04c403099184689990674f5b4259dc46bd8
    Passphrase:
    true

#### 现在智能合约已经部署到区块链上了，但是要挖矿才能生效，挖完就可以调用合约方法了 ####

> demo
    {
      abi: [{
          constant: false,
          inputs: [{...}],
          name: "print",
          outputs: [{...}],
          payable: false,
          stateMutability: "nonpayable",
          type: "function"
      }],
      address: undefined,
      transactionHash: "0xbe51755e1901b037dfd3e9a597a99111ce58d42da2f9fadf18e0909a5fb688fc"
    }
    > demo.print
    undefined
    > miner.start(1);admin.sleepBlocks(1);miner.stop();
    INFO [03-01|11:01:52] Updated mining threads                   threads=1
    INFO [03-01|11:01:52] Transaction pool price threshold updated price=18000000000
    INFO [03-01|11:01:52] Starting mining operation 
    INFO [03-01|11:01:52] Commit new mining work                   number=73 txs=1 uncles=0 elapsed=2.428ms
    INFO [03-01|11:02:53] Successfully sealed new block            number=73 hash=4b0335…049ed7
    INFO [03-01|11:02:53]  mined potential block                  number=73 hash=4b0335…049ed7
    INFO [03-01|11:02:53] Commit new mining work                   number=74 txs=0 uncles=0 elapsed=602.175µs
    true
    > demo.print
    function()
    true
    > demo.print.call("hello world")
    "hello world"