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Chainlink 价格数据

Chainlink 价格数据

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概述

本教程展示如何在智能合约中集成 Chainlink 价格 Feed，构建一个简单的价格感知 DApp——用户存入 ETH，合约基于实时 ETH/USD 价格计算美元价值并发放对应数量的代币。

主要内容

项目功能

ETH 存款应用：
  1. 用户向合约存入任意数量 ETH
  2. 合约读取 Chainlink ETH/USD 价格
  3. 按 $1 = 1 Token 的比例铸造代币给用户
  4. 用户可随时取出 ETH（按当前价格）

安装依赖

Terminal window
npm install @chainlink/contracts
# 或 Foundry
forge install smartcontractkit/chainlink-brownie-contracts

合约实现

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;


import "@chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";


contract ETHVault is ERC20, Ownable {
    AggregatorV3Interface public immutable priceFeed;


    mapping(address => uint256) public ethDeposited;
    uint256 public constant STALE_PRICE_THRESHOLD = 3600; // 1小时


    event Deposited(address indexed user, uint256 ethAmount, uint256 usdValue, uint256 tokensIssued);
    event Withdrawn(address indexed user, uint256 ethAmount, uint256 tokensBurned);


    error StalePriceData();
    error InvalidPrice();
    error InsufficientBalance();


    // Sepolia ETH/USD: 0x694AA1769357215DE4FAC081bf1f309aDC325306
    // 主网 ETH/USD: 0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419
    constructor(address _priceFeed, address _owner)
        ERC20("ETH Vault Token", "EVT")
        Ownable(_owner)
    {
        priceFeed = AggregatorV3Interface(_priceFeed);
    }


    // 获取 ETH/USD 价格（带安全检查）
    function getETHPrice() public view returns (uint256 price, uint8 decimals_) {
        (
            /* uint80 roundId */,
            int256 answer,
            /* uint256 startedAt */,
            uint256 updatedAt,
            /* uint80 answeredInRound */
        ) = priceFeed.latestRoundData();


        // 检查数据新鲜度
        if (block.timestamp - updatedAt > STALE_PRICE_THRESHOLD) revert StalePriceData();
        if (answer <= 0) revert InvalidPrice();


        return (uint256(answer), priceFeed.decimals());
    }


    // ETH 换算为 USD 金额（18 位精度）
    function ethToUSD(uint256 ethAmount) public view returns (uint256 usdAmount) {
        (uint256 price, uint8 priceDecimals) = getETHPrice();
        // ethAmount(18 decimals) * price(8 decimals) / 10^8 = USD(18 decimals)
        usdAmount = (ethAmount * price) / (10 ** priceDecimals);
    }


    // 存入 ETH，获取 Token
    function deposit() external payable {
        require(msg.value > 0, "Must deposit ETH");


        uint256 usdValue = ethToUSD(msg.value);
        uint256 tokensToMint = usdValue; // 1 USD = 1 Token


        ethDeposited[msg.sender] += msg.value;
        _mint(msg.sender, tokensToMint);


        emit Deposited(msg.sender, msg.value, usdValue, tokensToMint);
    }


    // 销毁 Token，取回对应 ETH
    function withdraw(uint256 tokenAmount) external {
        require(balanceOf(msg.sender) >= tokenAmount, "Insufficient tokens");


        // 计算对应的 ETH 数量
        (uint256 price, uint8 priceDecimals) = getETHPrice();
        // tokenAmount(18 decimals) * 10^8 / price(8 decimals) = ETH(18 decimals)
        uint256 ethAmount = (tokenAmount * (10 ** priceDecimals)) / price;


        require(address(this).balance >= ethAmount, "Insufficient ETH in vault");


        _burn(msg.sender, tokenAmount);
        ethDeposited[msg.sender] = ethDeposited[msg.sender] > ethAmount
            ? ethDeposited[msg.sender] - ethAmount
            : 0;


        payable(msg.sender).transfer(ethAmount);
        emit Withdrawn(msg.sender, ethAmount, tokenAmount);
    }


    // 查询当前 ETH 价格（用于前端显示）
    function getCurrentPrice() external view returns (uint256 priceUSD) {
        (uint256 price, uint8 priceDecimals) = getETHPrice();
        // 转换为 18 位精度的 USD 价格
        return price * (10 ** (18 - priceDecimals));
    }
}

测试（使用 Mock）

test/mocks/MockV3Aggregator.sol
pragma solidity ^0.8.20;


contract MockV3Aggregator {
    int256 private _price;
    uint8 private _decimals;
    uint256 private _updatedAt;


    constructor(uint8 decimals_, int256 initialPrice) {
        _decimals = decimals_;
        _price = initialPrice;
        _updatedAt = block.timestamp;
    }


    function latestRoundData() external view returns (
        uint80, int256, uint256, uint256, uint80
    ) {
        return (1, _price, block.timestamp, _updatedAt, 1);
    }


    function decimals() external view returns (uint8) { return _decimals; }


    // 测试用：更新价格
    function updateAnswer(int256 newPrice) external {
        _price = newPrice;
        _updatedAt = block.timestamp;
    }
}
describe("ETHVault", function () {
    it("应该按 Chainlink 价格铸造 Token", async function () {
        const MockAggregator = await ethers.getContractFactory("MockV3Aggregator");
        const mockFeed = await MockAggregator.deploy(8, 200000000000n); // $2000 (8 decimals)


        const ETHVault = await ethers.getContractFactory("ETHVault");
        const vault = await ETHVault.deploy(await mockFeed.getAddress(), owner.address);


        // 存入 1 ETH
        await vault.connect(alice).deposit({ value: parseEther("1") });


        // 应该得到 2000 Token（1 ETH × $2000/ETH = $2000 = 2000 Token）
        expect(await vault.balanceOf(alice.address)).to.equal(parseEther("2000"));
    });
});

前端集成

// 显示实时 ETH 价格
function ETHPriceDisplay() {
    const { data: price } = useReadContract({
        address: VAULT_ADDRESS,
        abi: VAULT_ABI,
        functionName: "getCurrentPrice",
        query: { refetchInterval: 30000 }, // 每 30 秒刷新
    });


    return (
        <p>ETH 当前价格: ${price ? (Number(price) / 1e18).toFixed(2) : "..."} USD</p>
    );
}

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