用Golang實現以太坊代幣轉帳

我的簡介

[HundredLee]

• 2013年創業，開始從事數字貨幣開發工做，區塊鏈開發工程師、iOS&Web開發者。目前擔任國內知名數字貨幣交易平臺開發商CTO。四年的技術沉澱，客戶已遍及國內外，並有自主研發的JAVA高速撮合引擎。
• 微博 ：weibo.com/hundredlee2…
• 郵箱 ：hundred9411#gmail.com
• Blog : blog.sodroid.com

什麼是代幣？

2017年區塊鏈火爆了整個互聯網金融圈，特別是ico的出現，讓不少人開始認識了數字貨幣。咱們知道以太坊（Ethereum）是目前最受歡迎的數字貨幣和區塊鏈系統，而eth每一個已經達到了2000+RMB。我記得剛認識以太坊的時候，是三十多一枚。

• 那麼什麼是代幣呢？在以太坊區塊鏈中，咱們稱代幣爲Token，是以太坊區塊鏈中每一個人均可以任意發行的數字資產。而且它必須是遵循erc20標準的，至於erc20標準，你們能夠參考這篇文章 theethereum.wiki/w/index.php…
• 它實際上一段智能合約代碼，智能合約代碼中必需要有如下的一些function 和 event。

contract ERC20 {
      function totalSupply() constant returns (uint totalSupply);
      function balanceOf(address _owner) constant returns (uint balance);
      function transfer(address _to, uint _value) returns (bool success);
      function transferFrom(address _from, address _to, uint _value) returns (bool success);
      function approve(address _spender, uint _value) returns (bool success);
      function allowance(address _owner, address _spender) constant returns (uint remaining);
      event Transfer(address indexed _from, address indexed _to, uint _value);
      event Approval(address indexed _owner, address indexed _spender, uint _value);
 }複製代碼

• 智能合約代碼是運行在以太坊智能合約虛擬機中的。有興趣的同窗，能夠學習一下。附上文檔：solidity.readthedocs.io/en/latest/i…

• 咱們看到上面那段相似golang中interface的代碼，裏面分別包含了總量、餘額、轉帳等方法。咱們今天重點講的其實就是用golang來實現transfer、transferFrom方法。

• 下面進入主題。

鏈接以太坊RPC節點

• 目前普遍使用的是go-ethereum，他的客戶端名是geth。你能夠經過編譯、安裝等方式把節點搭建在你的電腦或者服務器中，並開啓rpc服務。本文省略這一步驟，網上有很文章供你瞭解。
• 附上github：github.com/ethereum/go…
• geth默認的rpc端口是8545，我使用默認端口，後面咱們都用http://127.0.0.1:8545做爲咱們的rpc鏈接。

首先獲取go-ethereum代碼

• go get github.com/ethereum/go-ethereum
• 而後咱們go-ethereum目錄，若是你的golang環境沒有問題，那麼應該是這個路徑。
• cd $GOPATH/src/github.com/ethereum/go-ethereum
• 當你進入目錄，看到代碼已經完整拉取下來，那麼咱們就能夠進行下一步了。

鏈接RPC節點

• Dont bb..咱們直接上代碼。

import (
    "github.com/ethereum/go-ethereum/rpc"
    "github.com/ethereum/go-ethereum/ethclient"
)

rpcDial, err := rpc.Dial("http://127.0.0.1:8545")
if err != nil {
    panic(err);    
}
client := ethclient.NewClient(rpcDial)複製代碼

• 若是沒有panic，那麼咱們已經成功鏈接了節點。(^__^)

建立測試帳戶

• 要進行轉帳測試，那麼咱們須要兩個以太坊帳戶。咱們用golang來生成，咱們知道以太坊的帳戶私鑰是放在keystore文件中的，是一段json，而且建立的時候能夠設置密碼。跟比特幣的wallet.dat文件是同樣的意思，不見哪同樣，你的資產就永遠留在區塊鏈網絡中，再也沒法找回。
• 下面咱們用代碼建立兩個以太坊帳戶。

import (
    "github.com/ethereum/go-ethereum/accounts/keystore"
)

ks := keystore.NewKeyStore("/", keystore.StandardScryptN, keystore.StandardScryptP)

address, _ := ks.NewAccount("password")
account, err := ks.Export(address, "password", "password")

if err != nil {
    panic(err)
}複製代碼

• 從上面的代碼咱們能夠看到，我建立了一個以太坊的帳戶，而且密碼設置爲password，並導出。最終account變量就是帳戶的私鑰，是一段json文本。咱們能夠看看它大概長什麼樣。
• 經過address變量，咱們能夠得到帳戶的地址。好比這樣 address.Address.Hex()

{"address":"41e2f6a4eb0e61f627207ec4a3f7098388174368","crypto":{"cipher":"aes-128-ctr","ciphertext"
:"c0b10f9a3ca83837de83d38ca95bef200170d97e818f15bbc35642b6076c4a16",
"cipherparams":{"iv":"e46c3f2c76b35eedd7b065677faf6927"},
"kdf":"scrypt",
"kdfparams":
{"dklen":32,"n":262144,"p":1,"r":8,"salt"
:"05c8493a6a8518451c18ac05785e6c60507d906b130ee859e99804f0df90b63d"},
"mac"
:"62f52d9c4a078765b496cf76ed50634199c509e2d6e91106e24276d51124b971"}
,"id"
:"6c00339c-773b-4862-bb61-3a51a6f671ee",
"version":3}複製代碼

• 反正就是這麼一段json，必定要妥善保存。

生成代幣文件

• 打開 cd $GOPATH/src/github.com/ethereum/go-ethereum/cmd/abigen 你能看到main.go文件

• 執行 go build main.go，會在目錄下生成一個main的二進制文件。

• 將如下的json 保存爲token.abi，並放在當前目錄下。

[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"bytes32"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"stop","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"guy","type":"address"},{"name":"wad","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"owner_","type":"address"}],"name":"setOwner","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"src","type":"address"},{"name":"dst","type":"address"},{"name":"wad","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"dst","type":"address"},{"name":"wad","type":"uint128"}],"name":"push","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"name_","type":"bytes32"}],"name":"setName","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"wad","type":"uint128"}],"name":"mint","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"src","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"stopped","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"authority_","type":"address"}],"name":"setAuthority","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"src","type":"address"},{"name":"wad","type":"uint128"}],"name":"pull","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"wad","type":"uint128"}],"name":"burn","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"bytes32"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"dst","type":"address"},{"name":"wad","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"start","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"authority","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"src","type":"address"},{"name":"guy","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"inputs":[{"name":"symbol_","type":"bytes32"}],"payable":false,"type":"constructor"},{"anonymous":true,"inputs":[{"indexed":true,"name":"sig","type":"bytes4"},{"indexed":true,"name":"guy","type":"address"},{"indexed":true,"name":"foo","type":"bytes32"},{"indexed":true,"name":"bar","type":"bytes32"},{"indexed":false,"name":"wad","type":"uint256"},{"indexed":false,"name":"fax","type":"bytes"}],"name":"LogNote","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"authority","type":"address"}],"name":"LogSetAuthority","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"}],"name":"LogSetOwner","type":"event"},{"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"}]複製代碼

• 執行命令 ./main --abi token.abi --pkg main --type Token --out token.go

• 咱們能夠看到目錄下生成了一個token.go文件。大功告成。

開始轉帳

• 首先就把上一步生成的token.go拖入項目中。
• 接下來的敘述，我寫在代碼的註釋裏

import (
    "github.com/ethereum/go-ethereum/accounts/abi/bind"
)

//首先導入上面生成的帳戶密鑰（json）和密碼
auth, err := bind.NewTransactor(strings.NewReader("json"), "password")
//這句用的是生成的token.go裏面的方法
//client變量是咱們第一步鏈接以太坊rpc節點的時候建立的

//contractAddress 是代幣地址，好比eos 的地址是0x86fa049857e0209aa7d9e616f7eb3b3b78ecfdb0
//那麼咱們轉帳針對的就是帳戶裏的eos代幣
//具體看這裏 https://etherscan.io/token/0x86fa049857e0209aa7d9e616f7eb3b3b78ecfdb0
token, err := NewToken(common.HexToAddress("0x86fa049857e0209aa7d9e616f7eb3b3b78ecfdb0"), client)
if err != nil {
    panic(err)
}

//每一個代幣都會有相應的位數，例如eos是18位，那麼咱們轉帳的時候，須要在金額後面加18個0
decimal, err := token.Decimals(nil)
if err != nil {
    panic(err)
}

//這是處理位數的代碼段
tenDecimal := big.NewFloat(math.Pow(10, float64(decimal)))
convertAmount, _ := new(big.Float).Mul(tenDecimal, amount).Int(&big.Int{})

//而後就能夠轉帳到你須要接受的帳戶上了
//toAddress 是接受eos的帳戶地址
txs, err := token.Transfer(auth, common.HexToAddress(toAddress), convertAmount)複製代碼

• 由此，轉帳就大功告成了。另外，token.go裏面還有不少其餘的方法，有興趣的同窗，能夠自行研究。

本文結束

• 個人以太坊地址 0x67f883a42031215622e0b84c96d0E4DcA7A3ce81
• 哈哈哈，支持eos、omg、tnt等代幣的捐贈，請我喝杯星巴克。
• 固然，eth也是不會拒接的。或者你能夠掃碼，下面是個人以太坊收款二維碼。謝謝哦。

-w265