用python实现区块链功能

实现区块链需要使用Python编程语言，下面是一个简单的示例。

首先，我们需要定义一个Block类来表示区块：

import hashlib
import datetime as date

class Block:
    def __init__(self, index, timestamp, data, previous_hash):
        self.index = index
        self.timestamp = timestamp
        self.data = data
        self.previous_hash = previous_hash
        self.hash = self.calculate_hash()

    def calculate_hash(self):
        sha = hashlib.sha256()
        sha.update(str(self.index).encode('utf-8') + 
                   str(self.timestamp).encode('utf-8') + 
                   str(self.data).encode('utf-8') + 
                   str(self.previous_hash).encode('utf-8'))
        return sha.hexdigest()

然后，我们需要定义一个Blockchain类来表示整个区块链：

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

    def create_genesis_block(self):
        # Manually construct a block with
        # index zero and arbitrary previous hash
        return Block(0, date.datetime.now(), "Genesis Block", "0")

    def get_latest_block(self):
        return self.chain[-1]

    def add_block(self, new_block):
        new_block.previous_hash = self.get_latest_block().hash
        new_block.hash = new_block.calculate_hash()
        self.chain.append(new_block)

    def is_chain_valid(self):
        for i in range(1, len(self.chain)):
            current_block = self.chain[i]
            previous_block = self.chain[i - 1]

            if current_block.hash != current_block.calculate_hash():
                return False

            if current_block.previous_hash != previous_block.hash:
                return False

        return True

现在，我们可以创建一个区块链并添加一些块：

# Create the blockchain and add the genesis block
blockchain = Blockchain()

# Add some blocks to the chain
blockchain.add_block(Block(1, date.datetime.now(), "Block 1", ""))
blockchain.add_block(Block(2, date.datetime.now(), "Block 2", ""))
blockchain.add_block(Block(3, date.datetime.now(), "Block 3", ""))

最后，我们可以验证整个区块链是否有效：

# Check if the blockchain is valid
print("Is blockchain valid? ", blockchain.is_chain_valid())

完整的代码如下：

import hashlib
import datetime as date

class Block:
    def __init__(self, index, timestamp, data, previous_hash):
        self.index = index
        self.timestamp = timestamp
        self.data = data
        self.previous_hash = previous_hash
        self.hash = self.calculate_hash()

    def calculate_hash(self):
        sha = hashlib.sha256()
        sha.update(str(self.index).encode('utf-8') + 
                   str(self.timestamp).encode('utf-8') + 
                   str(self.data).encode('utf-8') + 
                   str(self.previous_hash).encode('utf-8'))
        return sha.hexdigest()

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

    def create_genesis_block(self):
        # Manually construct a block with
        # index zero and arbitrary previous hash
        return Block(0, date.datetime.now(), "Genesis Block", "0")

    def get_latest_block(self):
        return self.chain[-1]

    def add_block(self, new_block):
        new_block.previous_hash = self.get_latest_block().hash
        new_block.hash = new_block.calculate_hash()
        self.chain.append(new_block)

    def is_chain_valid(self):
        for i in range(1, len(self.chain)):
            current_block = self.chain[i]
            previous_block = self.chain[i - 1]

            if current_block.hash != current_block.calculate_hash():
                return False

            if current_block.previous_hash != previous_block.hash:
                return False

        return True


# Create the blockchain and add the genesis block
blockchain = Blockchain()

# Add some blocks to the chain
blockchain.add_block(Block(1, date.datetime.now(), "Block 1", ""))
blockchain.add_block(Block(2, date.datetime.now(), "Block 2", ""))
blockchain.add_block(Block(3, date.datetime.now(), "Block 3", ""))

# Check if the blockchain is valid
print("Is blockchain valid? ", blockchain.is_chain_valid())