python，Django实现区块链项目

import json
import  hashlib
from time import time
class BlockChain(object):
    def __init__(self):
        self.blockchain = []
        self.current_transactions =[]
        self.new_block()
    def __str__(self): #java to string
        return f'blockchain:{self.blockchain}' 
    def new_block(self):
        block ={
            'index':len(self.blockchain),
            'timestramp':time(),
            'transaction':self.current_transactions,
            'nonce':-1,
            'pre_hash':None if len(self.blockchain) == 0 else self.get_block_hash(self.blockchain[-1])
        }
        hash = None
        while not self.valid_proot(hash,4):
            block['nonce'] = block['nonce'] + 1
            hash =self.get_block_hash(block)
        # 把当前区块添加在区块链中
        self.blockchain.append(block)
        self.current_transactions =[] #空列表
        return block
    def get_block_hash(self, block):
        block_str = json.dumps(block, sort_keys=True).encode('UTF-8')
        return hashlib.sha256(block_str).hexdigest()
    def new_tarnsaction(self,sender,receive,amount):
        self.current_transactions.append({
            'sender':sender,
            'receive':receive,
            'amount':amount
        })
    def valid_proot(self,hash,difficulty):
        if hash == None or hash[:difficulty] != '0000':
            return False
        else:
            return True
if __name__ == '__main__':
    bc =BlockChain()
    print(bc.blockchain)
    for i in range(3):
        bc.new_block()