区块链学习（三）区块链实例

1.计算哈希，创建 区块

package coreimport (   "crypto/sha256"   "encoding/hex"   "time")type Block struct {   Index        int64  // 区块编号   Timestmp     int64  // 区块时间戳   PreBolckHash string // 上一个区块的哈希值   Hash         string // 当前区块哈希值   Data         string // 区块数据}// 计算哈希func CalculateHash(b Block) string {   // 数据不允许修改   // 把 数据 包含在hash运算的数值里面， ，任何一个模块数据的修改，都会导致区块链， 链式数据结构的破坏   blockData := string(b.Index)   string(b.Timestmp)   string(b.PreBolckHash)   HashInBytes := sha256.Sum256([]byte(blockData))   return hex.EncodeToString(HashInBytes[:])}// 生成新区块func GenerateNewBlock(preBlock Block, data string) Block {   newBlock := Block{}   // 新区块的index = 父区块的index 1   newBlock.Index = preBlock.Index   1   // 哈希值 = 父区块的哈希值   newBlock.PreBolckHash = preBlock.Hash   // 新区块的时间戳，==当前时间   newBlock.Timestmp = time.Now().Unix()   newBlock.Data = data   // 新区块的哈希 是计算得来的   newBlock.Hash = CalculateHash(newBlock)   return newBlock}// 生成创始区块func GenerateGenesisBlock() Block {   preBlock := Block{}   preBlock.Index = -1   preBlock.Timestmp = time.Now().Unix()   preBlock.Hash = CalculateHash(preBlock)   preBlock.Data = "Genesis Block(创始区块)"   GenerateNewBlock(preBlock, "Genesis Block")   return preBlock}

 

链式数据

package coreimport (   "fmt"   "log")type Blockchain struct {   // 数组   Blocks []*Block}func NewBlockchain() *Blockchain {   genesisBlock := GenerateGenesisBlock()   blockchain := Blockchain{}   blockchain.ApendBlock(&genesisBlock)   return &blockchain}func (bc *Blockchain) SendData(data string) {   proBlock := bc.Blocks[len(bc.Blocks)-1]   newBlock := GenerateNewBlock(*proBlock, data)   bc.ApendBlock(&newBlock)}func (bc *Blockchain) ApendBlock(newBlock *Block) {   // 防止越界   if len(bc.Blocks) == 0 {      bc.Blocks = append(bc.Blocks, newBlock)      return   }   if isValid(*newBlock, *bc.Blocks[len(bc.Blocks)-1]) {      bc.Blocks = append(bc.Blocks, newBlock)   } else {      log.Fatal("invalid block")   }}func (bc *Blockchain) Print() {   // 下划线表示赋值是忽略的   for _, block := range bc.Blocks {      fmt.Printf("Index: %d\n", block.Index)      fmt.Printf("Prev.Hash: %s\n", block.PreBolckHash)      fmt.Printf("Curr.Hash: %s\n", block.Hash)      fmt.Printf("Data: %s\n", block.Data)      fmt.Printf("Timestmp: %d\n", block.Timestmp)      fmt.Println("")   }}func isValid(newBlock Block, oldBlock Block) bool {   if newBlock.Index-1 != oldBlock.Index {      return false   }   if newBlock.PreBolckHash != oldBlock.Hash {      return false   }   if CalculateHash(newBlock) != newBlock.Hash {      return false   }   return true}

 

启动类

package mainimport "./core"func main() {   bc := core.NewBlockchain()   bc.SendData("Send 1 BTC to jacky")   bc.SendData("Send 1 EOS to jacky")   bc.Print()}

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