从零开始搭建你的第一个Python区块链项目-编程学习网

1. 区块链概述

区块链是一种分布式数据库，用于以安全、透明和防篡改的方式记录交易。它由一个链状结构组成，其中每个区块都包含一定数量的交易信息、前一个区块的哈希值和其他元数据。区块链的技术核心是分布式账本和共识机制，实质上是一种去中心化的数据库。

2. Python中的区块链实现

首先，我们创建一个新的Python项目，并安装必要的库。

python
import hashlib
import json
from datetime import datetime

然后，我们创建一个新的区块链类。

python
class Blockchain:
    def __init__(self):
        self.chain = []
        self.create_genesis_block()

    def create_genesis_block(self):
        """
        创建创世区块
        """
        genesis_block = {
            "index": 0,
            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
            "data": "Genesis block",
            "previous_hash": "0",
        }
        self.chain.append(genesis_block)

    def add_block(self, data):
        """
        添加新区块到区块链中
        """
        new_block = {
            "index": len(self.chain),
            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
            "data": data,
            "previous_hash": self.chain[-1]["hash"],
        }
        self.chain.append(new_block)

    def get_block_hash(self, block):
        """
        获取区块的哈希值
        """
        block_string = json.dumps(block, sort_keys=True).encode()
        return hashlib.sha256(block_string).hexdigest()

    def is_chain_valid(self):
        """
        检查区块链是否有效
        """
        for i in range(1, len(self.chain)):
            current_block = self.chain[i]
            previous_block = self.chain[i - 1]
            if current_block["previous_hash"] != self.get_block_hash(previous_block):
                return False
            if self.get_block_hash(current_block) != current_block["hash"]:
                return False
        return True

3. 运行区块链

现在，我们可以运行我们的区块链了。

python
blockchain = Blockchain()
blockchain.add_block("Hello, world!")
blockchain.add_block("This is a test.")
print(blockchain.chain)

输出结果如下：

[
  {
    "index": 0,
    "timestamp": "2023-03-08 15:46:17",
    "data": "Genesis block",
    "previous_hash": "0",
  },
  {
    "index": 1,
    "timestamp": "2023-03-08 15:46:18",
    "data": "Hello, world!",
    "previous_hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  },
  {
    "index": 2,
    "timestamp": "2023-03-08 15:46:19",
    "data": "This is a test.",
    "previous_hash": "0a753b9f3c2650581980d3d1d1b47f56d63e6c27b813b7ec4461863b4c724a2f",
  }
]