要说2018年什么最火，无疑就是区块链。比特币的疯狂上涨，每个比特币超过了1万美金。随之而来的就是区块链的技术。
以太坊（Ethereum）并不是一个机构，而是一款能够在区块链上实现智能合约、开源的底层系统。本文主要是通过以太坊，创建私有链，实现挖矿和交易。
安装golang
克隆项目
$ git clone https://github.com/golang/go.git
安装go 1.4
golang 是自编译，所以如果安装版本 >=1.5 需要先编译1.4版本，然后再安装其他版本
$ cp -r go/ $HOME/go1.4 #复制一份文件夹，用于编译1.4版本
$ cd $HOME/go1.4
$ git checkout release-branch.go1.4
$ cd src
$ ./make.bash # 进行编译
编译之后，开始安装go 1.9版本
$ cd $HOME/install/go
$ git checkout release-branch.go1.9
$ cd src/
$ ./all.bash #安装1.9版本
##### Building Go bootstrap tool.
cmd/dist
##### Building Go toolchain using /home/test/go1.4.
bootstrap/cmd/internal/dwarf
bootstrap/cmd/internal/objabi
bootstrap/cmd/internal/src
bootstrap/cmd/internal/sys
bootstrap/cmd/internal/obj
bootstrap/cmd/internal/obj/arm
bootstrap/cmd/internal/obj/arm64
bootstrap/cmd/internal/obj/mips
bootstrap/cmd/internal/obj/ppc64
bootstrap/cmd/internal/obj/s390x
... ##各种编译安装信息
##### API check
Go version is "go1.9.2", ignoring -next /home/test/install/go/api/next.txt
ALL TESTS PASSED
---
Installed Go for linux/amd64 in /home/test/install/go
Installed commands in /home/test/install/go/bin
*** You need to add /home/test/install/go/bin to your PATH.
配置环境变量
$ export PATH=$PATH:/home/test/install/go/bin
查看安装版本
$ go version
go version go1.9.2 linux/amd64
克隆go-ethereum
$ git clone https://github.com/ethereum/go-ethereum.git
安装以太坊
$ make geth
build/env.sh go run build/ci.go install ./cmd/geth
>>> /home/test/install/go/bin/go install -ldflags -X main.gitCommit=5d4267911a7791bfa60f275a97347372fbf0ce99 -v ./cmd/geth
github.com/ethereum/go-ethereum/common/hexutil
github.com/ethereum/go-ethereum/crypto/sha3
github.com/ethereum/go-ethereum/common
...
github.com/ethereum/go-ethereum/vendor/github.com/gizak/termui
github.com/ethereum/go-ethereum/vendor/github.com/naoina/go-stringutil
github.com/ethereum/go-ethereum/vendor/github.com/naoina/toml/ast
github.com/ethereum/go-ethereum/vendor/github.com/naoina/toml
github.com/ethereum/go-ethereum/cmd/geth
Done building.
Run "/home/test/install/go-ethereum/build/bin/geth" to launch geth.
创建连接
$ ln -s /home/test/install/go-ethereum/build/bin/geth /usr/local/bin/geth
创建私有链
创建创世区块
{
"config": {
"chainId": 15,
"homesteadBlock": 0,
"eip155Block": 0,
"eip158Block": 0
},
"coinbase" : "0x0000000000000000000000000000000000000000",
"difficulty" : "0x40000",
"extraData" : "",
"gasLimit" : "0xffffffff",
"nonce" : "0x0000000000000042",
"mixhash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
"parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
"timestamp" : "0x00",
"alloc": { }
}
$ mkdir my_chain
$ cd my_chain
$ vim genesis.json # json文件的内容是上面的json字符串
创建创世节点，并且初始化数据
$ geth --datadir data00 init genesis.json
data00就是用来保存创世节点的数据
启动节点，指定networkid
$ geth --datadir ./data00 --networkid 5201314 console #使用console 支持命令行模式
创建节点的账号
# 在console命令模式下
> personal.newAccount("123")
"0x9ff8676095e5999bf82eafeab98192e33ad74364"
开始进行挖矿
> miner.start()
INFO [01-23|00:14:37] Updated mining threads threads=0
INFO [01-23|00:14:37] Transaction pool price threshold updated price=18000000000
INFO [01-23|00:14:37] Etherbase automatically configured address=0x9FF8676095e5999bf82EafEaB98192E33ad74364
null
> INFO [01-23|00:14:37] Starting mining operation
INFO [01-23|00:14:37] Commit new mining work number=1 txs=0 uncles=0 elapsed=146.511µs
INFO [01-23|00:14:43] Generating DAG in progress epoch=0 percentage=0 elapsed=4.529s
INFO [01-23|00:14:48] Generating DAG in progress epoch=0 percentage=1 elapsed=8.913s
INFO [01-23|00:14:52] Generating DAG in progress epoch=0 percentage=2 elapsed=13.169s
INFO [01-23|00:14:56] Generating DAG in progress epoch=0 percentage=3 elapsed=17.298s
INFO [01-23|00:15:01] Generating DAG in progress epoch=0 percentage=4 elapsed=21.964s
...
等到percentage加载到100的时候就开始进行挖矿
结束挖矿
> miner.stop()
查看挖矿的金额
> eth.getBalance(eth.accounts[0])
5000000000000000000
新开一个窗口，创建第二个节点
$ geth --datadir data01 init genesis.json
运行第二个节点
networkid需要和第一个账号相同
$ geth --datadir data01 --networkid 5201314 --ipcdisable --port 61910 --rpcport 8200 console #使用命令行模式
创建账号
> personal.newAccount("456")
"0xfc350d17b0fb92eeb0a3bab80116c27d9f7e40d1"
开始进行挖矿
> miner.start()
结束挖矿
> miner.stop()
用户交易
回到第一个节点
查看节点信息
> admin.nodeInfo.enode
"enode://49e538b3f090a04e97f56a7fd1e6223c29599535d5e93010349147dee334b690744504f057ae11adb2804baada222375a56398ef42be536c595c6197a4a7cb2d@[::]:30303"
切换到第二个节点窗口
建立联系, 添加第一个节点enode
admin.addPeer("enode://49e538b3f090a04e97f56a7fd1e6223c29599535d5e93010349147dee334b690744504f057ae11adb2804baada222375a56398ef42be536c595c6197a4a7cb2d@[::]:30303")
true
切换到第一个控制台
查看建立的联系数量
> net.peerCount
1
peerCount=1，说明已经建立了联系
开始进行交易
切换到一个控制台，交易之前，需要先解锁账号才行
> personal.unlockAccount(eth.accounts[0], "123")
true
返回true说明已经解锁成功
> eth.sendTransaction({from: "0x9ff8676095e5999bf82eafeab98192e33ad74364", to: "0xfc350d17b0fb92eeb0a3bab80116c27d9f7e40d1", value: web3.toWei(1, "ether")})
to和form分别是接受和发送的账号，也就是personal.listAccounts里面的账号
查看确认下交易信息
> eth.pendingTransactions
[{
blockHash: null,
blockNumber: null,
from: "0x9ff8676095e5999bf82eafeab98192e33ad74364",
gas: 90000,
gasPrice: 18000000000,
hash: "0x6146513432b27b6a27f54b64fcf0a30dc90290452dfd25e282a05aaf423f4afa",
input: "0x",
nonce: 0,
r: "0x77644ff132f800da9b2d8133c796916f956061a491b55e3cbbd0d710f5157199",
s: "0x9dbe268e152e5fc15421efa5b00e5d4a601ef4cb2655b577901fd96c5d3c959",
to: "0xfc350d17b0fb92eeb0a3bab80116c27d9f7e40d1",
transactionIndex: 0,
v: "0x42",
value: 1000000000000000000
}]
开始进行挖矿，使交易生效
> miner.start()
确认交易是否成功
在一个和第二个控制台分别运行命令，确认是否交易成功
> eth.getBalance(eth.accounts[0])
总结
挖矿对电脑要求比较高，我使用阿里云的服务器，1核1G基本的配置，两个节点同时挖矿，经常出现CPU吃满的情况。
