python区块及区块链的开发详解

来源：jb51　　时间：2019/7/4 8:33:57　　对本文有异议

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 datetime
import hashlib
from Message import DaDaMessage, InvalidMessage
from Transaction import Transaction
class 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, Block
from Message import InvalidMessage, DaDaMessage
from 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)