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区块链基础概念
区块链核心特性
python
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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):
import hashlib
sha = hashlib.sha256()
sha.update(f"{self.index}{self.timestamp}{self.data}{self.previous_hash}".encode('utf-8'))
return sha.hexdigest()
# 创建创世区块
genesis_block = Block(0, "2023-01-01", "Genesis Block", "0")
print(f"创世区块哈希: {genesis_block.hash}")
Web3.py 入门
连接以太坊网络
python
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from web3 import Web3
# 连接Infura节点
infura_url = "https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID"
w3 = Web3(Web3.HTTPProvider(infura_url))
# 检查连接
print(f"是否已连接: {w3.isConnected()}")
print(f"最新区块号: {w3.eth.block_number}")
# 获取账户余额
address = "0x742d35Cc6634C0532925a3b844Bc454e4438f44e" # 示例地址
balance = w3.eth.get_balance(address)
print(f"余额: {w3.fromWei(balance, 'ether')} ETH")
智能合约交互
python
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# 合约ABI示例
contract_abi = '''
[
{
"inputs": [],
"name": "get",
"outputs": [{"name": "","type": "uint256"}],
"stateMutability": "view",
"type": "function"
},
{
"inputs": [{"name": "x","type": "uint256"}],
"name": "set",
"outputs": [],
"stateMutability": "nonpayable",
"type": "function"
}
]
'''
# 合约地址
contract_address = "0x1234567890123456789012345678901234567890"
# 创建合约实例
contract = w3.eth.contract(address=contract_address, abi=contract_abi)
# 调用只读函数
current_value = contract.functions.get().call()
print(f"当前值: {current_value}")
# 发送交易(需要账户和私钥)
'''
account = "0xYourAccountAddress"
private_key = "YourPrivateKey"
nonce = w3.eth.get_transaction_count(account)
tx = contract.functions.set(42).buildTransaction({
'chainId': 1,
'gas': 200000,
'gasPrice': w3.toWei('50', 'gwei'),
'nonce': nonce
})
signed_tx = w3.eth.account.sign_transaction(tx, private_key)
tx_hash = w3.eth.send_raw_transaction(signed_tx.rawTransaction)
print(f"交易哈希: {tx_hash.hex()}")
'''
智能合约开发
Solidity基础合约
solidity
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract SimpleStorage {
uint256 private value;
event ValueChanged(uint256 newValue);
function get() public view returns (uint256) {
return value;
}
function set(uint256 newValue) public {
value = newValue;
emit ValueChanged(newValue);
}
}
使用Brownie部署合约
python
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from brownie import accounts, SimpleStorage
def deploy_simple_storage():
# 加载账户
account = accounts[0]
# 部署合约
simple_storage = SimpleStorage.deploy({"from": account})
# 初始值
initial_value = simple_storage.get()
print(f"初始值: {initial_value}")
# 更新值
transaction = simple_storage.set(42, {"from": account})
transaction.wait(1) # 等待1个区块确认
# 新值
updated_value = simple_storage.get()
print(f"更新后的值: {updated_value}")
return simple_storage
def main():
deploy_simple_storage()
https://ethereum.org/static/8ea7775026b7fac7b16188a50a60f70d/302a4/developers.png
NFT开发实战
ERC721合约示例
solidity
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
contract MyNFT is ERC721 {
using Counters for Counters.Counter;
Counters.Counter private _tokenIds;
constructor() ERC721("MyNFT", "MNFT") {}
function mintNFT(address recipient, string memory tokenURI)
public
returns (uint256)
{
_tokenIds.increment();
uint256 newItemId = _tokenIds.current();
_mint(recipient, newItemId);
_setTokenURI(newItemId, tokenURI);
return newItemId;
}
}
使用Python铸造NFT
python
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from brownie import accounts, network, config, MyNFT
from scripts.helpful_scripts import get_account
from pathlib import Path
import requests
import json
def deploy_and_mint():
account = get_account()
my_nft = MyNFT.deploy({"from": account})
# 上传元数据到IPFS
token_uri = upload_to_ipfs("nft_metadata.json")
# 铸造NFT
tx = my_nft.mintNFT(account, token_uri, {"from": account})
tx.wait(1)
print(f"NFT铸造成功！查看地址: {my_nft.address}")
def upload_to_ipfs(filepath):
with Path(filepath).open("rb") as fp:
file_binary = fp.read()
ipfs_url = "http://127.0.0.1:5001"
endpoint = "/api/v0/add"
response = requests.post(ipfs_url + endpoint, files={"file": file_binary})
ipfs_hash = response.json()["Hash"]
return f"ipfs://{ipfs_hash}"
def main():
deploy_and_mint()
https://miro.medium.com/max/1400/1*8NgGYtqkYOwesVQdI3VQYw.png
DeFi应用开发
代币合约(ERC20)
solidity
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract MyToken is ERC20 {
constructor(uint256 initialSupply) ERC20("MyToken", "MTK") {
_mint(msg.sender, initialSupply);
}
}
查询代币余额
python
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from web3 import Web3
# 连接节点
w3 = Web3(Web3.HTTPProvider("https://mainnet.infura.io/v3/YOUR_PROJECT_ID"))
# ERC20 ABI片段
erc20_abi = '''
[
{
"constant": true,
"inputs": [{"name": "_owner", "type": "address"}],
"name": "balanceOf",
"outputs": [{"name": "balance", "type": "uint256"}],
"type": "function"
}
]
'''
# 代币合约地址
token_address = "0x6B175474E89094C44Da98b954EedeAC495271d0F" # DAI合约
user_address = "0xYourWalletAddress"
# 创建合约实例
contract = w3.eth.contract(address=token_address, abi=erc20_abi)
# 查询余额
balance = contract.functions.balanceOf(user_address).call()
print(f"代币余额: {balance / 10**18}") # 假设代币有18位小数
区块链数据分析
分析交易数据
python
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import pandas as pd
from web3 import Web3
w3 = Web3(Web3.HTTPProvider("https://mainnet.infura.io/v3/YOUR_PROJECT_ID"))
def get_block_data(block_number):
block = w3.eth.get_block(block_number, full_transactions=True)
return {
"block_number": block.number,
"timestamp": block.timestamp,
"miner": block.miner,
"gas_used": block.gasUsed,
"gas_limit": block.gasLimit,
"transaction_count": len(block.transactions)
}
# 获取最近10个区块数据
blocks_data = [get_block_data(w3.eth.block_number - i) for i in range(10)]
df = pd.DataFrame(blocks_data)
# 数据分析
print(df.describe())
print("\nGas使用率:")
df['gas_usage'] = df['gas_used'] / df['gas_limit']
print(df[['block_number', 'gas_usage']])
可视化交易趋势
python
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import matplotlib.pyplot as plt
# 准备数据
df['datetime'] = pd.to_datetime(df['timestamp'], unit='s')
# 创建图表
plt.figure(figsize=(12, 6))
plt.plot(df['datetime'], df['gas_usage'], marker='o')
plt.title('区块Gas使用率趋势')
plt.xlabel('时间')
plt.ylabel('Gas使用率')
plt.grid(True)
plt.savefig('gas_usage_trend.png')
plt.show()
安全最佳实践
智能合约安全检测
python
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from slither import Slither
from slither.detectors import all_detectors
def analyze_contract(contract_path):
# 加载合约
slither = Slither(contract_path)
# 运行所有检测器
detectors = [getattr(all_detectors, d) for d in all_detectors.__all__]
print(f"分析合约: {contract_path}")
print("=" * 50)
for detector in detectors:
detector = detector(slither)
detector_results = detector.detect()
if detector_results:
print(f"\n{detector.ARGUMENT}:")
for result in detector_results:
print(f"- {result['description']}")
print(f" 位置: {result['source_mapping']}")
# 分析合约
analyze_contract("SimpleStorage.sol")
常见漏洞防护
重入攻击防护:
solidity
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// 使用OpenZeppelin的ReentrancyGuard
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
contract SecureContract is ReentrancyGuard {
function safeWithdraw() public nonReentrant {
// 提款逻辑
}
}
整数溢出防护:
solidity
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// 使用SafeMath(0.8.0+版本已内置)
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
contract SafeMathExample {
using SafeMath for uint256;
function safeAdd(uint256 a, uint256 b) public pure returns (uint256) {
return a.add(b);
}
}
Web3开发工具链
| 工具名称 | 用途 | 适用场景 |
|---|---|---|
| Web3.py | 以太坊交互库 | 后端服务、脚本 |
| Brownie | 开发框架 | 合约测试、部署 |
| Hardhat | 开发环境 | 专业合约开发 |
| Ganache | 本地测试链 | 开发测试 |
| Infura/Alchemy | 节点服务 | 生产环境连接 |
| OpenZeppelin | 合约库 | 安全合约开发 |
| IPFS | 去中心化存储 | NFT元数据存储 |
去中心化应用(DApp)架构
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dapp_project/ ├── client/ # 前端代码 │ ├── public/ # 静态文件 │ └── src/ # React/Vue代码 ├── contracts/ # 智能合约 │ ├── contracts/ # Solidity代码 │ ├── tests/ # 合约测试 │ └── scripts/ # 部署脚本 ├── backend/ # 后端服务(可选) │ ├── api/ # API路由 │ └── services/ # 业务逻辑 └── docs/ # 项目文档
前端集成示例
javascript
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import { ethers } from "ethers";
import ABI from "./contractABI.json";
async function connectWallet() {
if (window.ethereum) {
try {
// 请求账户访问
const accounts = await window.ethereum.request({
method: "eth_requestAccounts"
});
const provider = new ethers.providers.Web3Provider(window.ethereum);
const signer = provider.getSigner();
// 合约实例
const contractAddress = "0x123...";
const contract = new ethers.Contract(contractAddress, ABI, signer);
// 调用合约
const value = await contract.get();
console.log("当前值:", value.toString());
} catch (error) {
console.error("用户拒绝访问:", error);
}
} else {
alert("请安装MetaMask!");
}
}
结语与学习路径
https://ethereum.org/static/4d030a6f9c1e4a919e775cf12a8dd192/302a4/learn.png
通过这八篇系列教程，你已经掌握了：
区块链基础原理与Python实现
Web3.py与以太坊交互
智能合约开发与部署
NFT与DeFi应用开发
区块链数据分析
安全最佳实践
完整DApp架构
下一步学习建议：
深入协议层：
学习以太坊EVM原理
研究零知识证明(ZKP)技术
探索Layer2解决方案
参与生态：
贡献开源Web3项目
参加黑客松活动
加入DAO组织
专业领域：
DeFi协议开发
NFT平台架构
区块链安全审计
扩展知识：
IPFS与去中心化存储
Oracles与链外数据
跨链技术
区块链技术正在重塑互联网未来，Python作为Web3开发的重要工具，将持续发挥关键作用。保持学习，你将成为这一变革的引领者！