python区块及区块链的开发详解

2019-11-25 12:32:03

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接着上一篇交易记录整合交易类，这里描述区块的开发。

首先我们要明白一个区块，需要的内容，包括交易记录集合，时间戳，哈希，上一个区块的哈希。明白了这个，下面就容易代码开发了。

import datetimeimport hashlibfrom Message import DaDaMessage, InvalidMessagefrom Transaction import Transactionclass Block:  #不定参数，*args,区块集合  def __init__(self, *args):    self.messagelist = [] # 存储多个交易记录    self.timestamp = None # 存储多个记录最终锁定时间    self.hash = None    self.preHash = None    if args:      for arg in args:        self.add_message(arg)  def add_message(self, message): # 添加 交易信息    # 区分第一条与后面多条，是否需要链接    if len(self.messagelist) > 0:      message.link(self.messagelist[-1]) # 链接最后一个    message.seal() # 密封    message.validate() # 校验    self.messagelist.append(message)  def link(self, block): # 区块链接    self.preHash = block.hash  def seal(self): # 密封当前hash    self.timestamp = datetime.datetime.now()    self.hash = self.hash_block()  def hash_block(self): # 密封上一块哈希，时间戳，交易记录的最后一个    return hashlib.sha512(      (str(self.timestamp) + str(self.preHash) + str(self.messagelist[-1].hash)).encode("utf-8")).hexdigest()  def validate(self): # 校验    for i, message in enumerate(self.messagelist): # 每个交易记录校验一下      message.validate() #每一条交易记录校验      if i > 0 and message.prev_hash != self.messagelist[i - 1].hash:        raise InvalidBlock("无效的block,交易记录被修改为在第{}条记录".format(i)+str(self))    return str(self) + "Ok"  def __repr__(self):    return "money block= hash:{},prehash:{},len:{},time:{}".format(self.hash, self.preHash, len(self.messagelist),                                    self.timestamp)

自定义异常：

class InvalidBlock(Exception):  def __init__(self,*args,**kwargs):    super(Exception,self).__init__(*args,**kwargs)

编写测试模块：

if __name__=="__main__":  t1 = Transaction("yicheng", "ddd1", 100)  t2 = Transaction("yicheng", "ddd2", 200)  t3 = Transaction("yicheng", "ddd3", 300)  t4 = Transaction("yicheng", "ddd4", 400)  m1 = DaDaMessage(t1)  m2 = DaDaMessage(t2)  m3 = DaDaMessage(t3)  m4 = DaDaMessage(t4)  try:    block1 = Block(m1, m2, m3)    block1.seal()    #测试篡改数据    #m3.data = "你妹的直播"    #block1.messagelist[0] = m3    print(block1.validate())  except InvalidMessage as e: #交易记录被修改    print(e)  except InvalidBlock as e: #区块被修改    print(e)

测试结果如下，为了打印需要，我改成了md5格式下的结果：

篡改区块信息的结果，可能结果不一样，因为修改的内容不一样，报的错误也不一样：

至此，已经完成了：交易记录，区块的开发，现在进行区块链的开发就比较容易了。实现代码如下：

from Block import InvalidBlock, Blockfrom Message import InvalidMessage, DaDaMessagefrom Transaction import Transaction# 区块链class Dada_BlockCoin:  def __init__(self):    self.blocklist = [] # 装载所有区块  def validate(self):#校验所有区块    for i, block in enumerate(self.blocklist):      try:        block.validate()      except InvalidBlockCoin as e:        raise InvalidBlockCoin("区块校验错误，区块索引{}".format(i))  def add_block(self, block): # 增加区块    if len(self.blocklist) > 0:      block.link(self.blocklist[-1]) #连接区块    block.seal()#密封    block.validate()#校验    self.blocklist.append(block)#添加到区块链中  def __repr__(self):    return "Dada_BlockCoin:{}".format(len(self.blocklist))

自定义异常：

class InvalidBlockCoin(Exception):  def __init__(self, *args, **kwargs):    super(Exception, self).__init__(*args, **kwargs)

编写测试模块：

if __name__ == "__main__":  t1 = Transaction("yicheng", "ddd1", 100)  t2 = Transaction("yicheng", "ddd2", 200)  t3 = Transaction("yicheng", "ddd3", 300)  t4 = Transaction("yicheng", "ddd4", 400)  t5 = Transaction("yicheng", "ddd5", 500)  t6 = Transaction("yicheng", "ddd6", 600)  m1 = DaDaMessage(t1)  m2 = DaDaMessage(t2)  m3 = DaDaMessage(t3)  m4 = DaDaMessage(t4)  m5 = DaDaMessage(t5)  m6 = DaDaMessage(t6)  try:    yin1 = Block(m1, m2)    yin1.seal()    yin2 = Block(m3, m4)    yin2.seal()    yin3 = Block(m5, m6)    yin3.seal()    # 篡改区块    #yin3.messagelist.append(m1)    coin = Dada_BlockCoin() # 区块链    coin.add_block(yin1)    coin.add_block(yin2)    coin.add_block(yin3)    coin.validate()    print(coin)  except InvalidMessage as e:    print(e)  except InvalidBlock as e:    print(e)  except InvalidBlockCoin as e:    print(e)

测试结果如下：