{"path":"1465232","ref":"序章.md","title":"第一节 一条简单的区块链","content":">[success] # 一条简单的区块链\n\n>[info] ### 区块\n\n- 区块链首先要有区块, 区块里存放着交易相关等数据 \n- 在本节中我们弄一个简单的区块, 仅仅包含最关键的信息，其数据结构在go语言定义如下：\r\n\r\n```go\ntype Block struct {\n   Timestamp     int64  \/\/时间戳\n   Data          []byte \/\/内容\n   PrevBlockHash []byte \/\/上一个区块的Hash\n   Hash          []byte \/\/当前区块的Hash\n}\n```\n\r\n- 其中Hash计算如下\n\r\n```go\n Hash = SHA256(PrevBlockHash + Timestamp + Data)\r\n```\n\r\n>[info] ### 区块链\r\n\n - 将一个个区块连接起来组成区块链\n\r\n```go\ntype Blockchain struct {\n   blocks []*Block   \/\/区块的切片即区块链\n}\n```\n\n>[warning] ### 一条简单的区块链\n\n- 通过区块和区块链实现一条简单的区块链\n\n```go\npackage main\n\nimport (\n   \"bytes\"\n   \"crypto\/sha256\"\n   \"fmt\"\n   \"strconv\"\n   \"time\"\n)\n\n\/\/区块\ntype Block struct {\n   Timestamp     int64\n   PrevBlockHash []byte\n   Hash          []byte\n   Data          []byte\n}\n\n\/\/区块链\ntype BlockChain struct {\n   blocks []*Block\n}\n\nfunc main() {\n   \/\/ 创建一个有创世块的链\n   blockchain := NewBlockChain()\n\n   \/\/添加新的块\n   blockchain.AddBlock(\"第二个块的内容\")\n   blockchain.AddBlock(\"第三个块的内容\")\n\n   \/\/遍历块\n   for _, block := range blockchain.blocks {\n      fmt.Printf(\"Timestamp: %s\\n\", time.Unix(block.Timestamp, 0).Format(\"2006-01-02 03:04:05\"))\n      fmt.Printf(\"Prev hash: %x\\n\", block.PrevBlockHash)\n      fmt.Printf(\"Data: %s\\n\", block.Data)\n      fmt.Printf(\"Hash: %x\\n\", block.Hash)\n      fmt.Println()\n   }\n}\n\nfunc NewBlock(data string, prevBlockHash []byte) *Block {\n   block := &Block{\n      Timestamp:     time.Now().Unix(),\n      PrevBlockHash: prevBlockHash,\n      Data:          []byte(data),\n      Hash:          []byte{},\n   }\n\n   \/\/设置当前块Hash\n   block.SetHash()\n   return block\n}\n\n\/\/ Hash = sha256(PrevBlockHash + Data + Timestamp)\nfunc (b *Block) SetHash() {\n   timestamp := []byte(strconv.FormatInt(b.Timestamp, 10))\n   headers := bytes.Join([][]byte{b.PrevBlockHash, b.Data, timestamp}, []byte{})\n   hash := sha256.Sum256(headers)\n   b.Hash = hash[:]\n}\n\n\/\/创世块\nfunc NewGenesisBlock() *Block {\n   return NewBlock(\"创世块\", []byte{})\n}\n\n\/\/创世链\nfunc NewBlockChain() *BlockChain {\n   return &BlockChain{[]*Block{NewGenesisBlock()}}\n}\n\n\/\/添加块\nfunc (blockchain *BlockChain) AddBlock(data string) {\n   prevBlock := blockchain.blocks[len(blockchain.blocks)-1] \/\/获取上一个区块的Hash\n   newBlock := NewBlock(data, prevBlock.Hash)\n   blockchain.blocks = append(blockchain.blocks, newBlock) \/\/把当前块添加到区块链上\n}\n```\n\r\n\r>[danger] ### 效果图\n```\nTimestamp: 2020-01-07 17:14:43\r\nPrev hash: \r\nData: 创世块\r\nHash: cf774fdc758cbb90e28cf053401927576a7350f778b60631112ce6fc074a278a\r\n\r\nTimestamp: 2020-01-07 17:14:43\r\nPrev hash: cf774fdc758cbb90e28cf053401927576a7350f778b60631112ce6fc074a278a\r\nData: 第二个块的内容\r\nHash: 3dd326874c10708e299c649760ed93689670a0d4fbeecd0a20755e0cbc9aded1\r\n\r\nTimestamp: 2020-01-07 17:14:43\r\nPrev hash: 3dd326874c10708e299c649760ed93689670a0d4fbeecd0a20755e0cbc9aded1\r\nData: 第三个块的内容\r\nHash: 5a2aaa1c443453717cbb92a85893c9600e2166555428a1d5714bf742842bb6cd\r\n```\n\r\n\r\n\r\n"}