NFT 与数字资产标准：ERC-721、ERC-1155 与元数据存储

interface IERC721 {
    // 余额与所有权
    function balanceOf(address owner) external view returns (uint256);
    function ownerOf(uint256 tokenId) external view returns (address);
    
    // 授权管理
    function approve(address to, uint256 tokenId) external;
    function getApproved(uint256 tokenId) external view returns (address);
    function setApprovalForAll(address operator, bool approved) external;
    function isApprovedForAll(address owner, address operator) external view returns (bool);
    
    // 转账
    function transferFrom(address from, address to, uint256 tokenId) external;
    function safeTransferFrom(address from, address to, uint256 tokenId) external;
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
    
    // 事件
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
}

function safeTransferFrom(address from, address to, uint256 tokenId) external {
    transferFrom(from, to, tokenId);
    // 检查接收方是否为合约，且是否实现了 IERC721Receiver
    require(
        to.code.length == 0 ||  // EOA
        IERC721Receiver(to).onERC721Received(msg.sender, from, tokenId, "") == 
            IERC721Receiver.onERC721Received.selector,
        "Transfer to non ERC721Receiver implementer"
    );
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract MyNFT is ERC721, ERC721URIStorage, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIdCounter;
    
    constructor() ERC721("MyNFT", "MNFT") {}
    
    function mint(address to, string memory uri) external onlyOwner returns (uint256) {
        uint256 tokenId = _tokenIdCounter.current();
        _tokenIdCounter.increment();
        _safeMint(to, tokenId);
        _setTokenURI(tokenId, uri);
        return tokenId;
    }
    
    function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) {
        super._burn(tokenId);
    }
    
    function tokenURI(uint256 tokenId) public view override(ERC721, ERC721URIStorage) returns (string memory) {
        return super.tokenURI(tokenId);
    }
}

interface IERC1155 {
    // 查询余额
    function balanceOf(address account, uint256 id) external view returns (uint256);
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids) 
        external view returns (uint256[] memory);
    
    // 授权与转账
    function setApprovalForAll(address operator, bool approved) external;
    function isApprovedForAll(address account, address operator) external view returns (bool);
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external;
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, 
        uint256[] calldata amounts, bytes calldata data) external;
    
    // 元数据
    function uri(uint256 id) external view returns (string memory);
}

{
    "name": "CryptoKitty #12345",
    "description": "A cute crypto-collectible cat",
    "image": "ipfs://QmXYZ.../image.png",
    "attributes": [
        { "trait_type": "Background", "value": "Blue" },
        { "trait_type": "Eyes", "value": "Green", "display_type": "number" },
        { "trait_type": "Level", "value": 5, "max_value": 10 }
    ],
    "animation_url": "ipfs://QmABC.../animation.glb",
    "external_url": "https://example.com/nft/12345"
}

# 安装 IPFS CLI
ipfs init
ipfs daemon

# 上传文件
ipfs add image.png
# 返回: added QmXYZ... image.png

# 固定（pin）到 Pinata/Infura 防止垃圾回收
curl -X POST "https://api.pinata.cloud/pinning/pinByHash" \
  -H "Authorization: Bearer YOUR_JWT" \
  -d '{"hashToPin":"QmXYZ..."}'

// 合约中使用 IPFS 链接
function tokenURI(uint256 tokenId) public view override returns (string memory) {
    return string(abi.encodePacked("ipfs://", _tokenCIDs[tokenId]));
}

import "@chainlink/contracts/src/v0.8/VRFConsumerBaseV2.sol";

contract RandomNFT is VRFConsumerBaseV2 {
    function requestRandomWords() external returns (uint256 requestId) {
        return COORDINATOR.requestRandomWords(
            keyHash, subscriptionId, requestConfirmations, callbackGasLimit, numWords
        );
    }
    
    function fulfillRandomWords(uint256 requestId, uint256[] memory randomWords) internal override {
        uint256 tokenId = requestIdToTokenId[requestId];
        // 使用随机数生成属性
        uint256 random = randomWords[0];
        attributes[tokenId] = Attribute({
            background: random % 10,
            eyes: (random / 10) % 10,
            ...
        });
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";

abstract contract Soulbound is ERC721 {
    error SoulboundTransferNotAllowed();
    
    function _beforeTokenTransfer(address from, address to, uint256 tokenId, uint256 batchSize) 
        internal virtual override {
        super._beforeTokenTransfer(from, to, tokenId, batchSize);
        // 仅允许铸造（from == address(0)）和销毁（to == address(0)）
        if (from != address(0) && to != address(0)) {
            revert SoulboundTransferNotAllowed();
        }
    }
}

interface IERC2981 {
    function royaltyInfo(uint256 tokenId, uint256 salePrice) 
        external view returns (address receiver, uint256 royaltyAmount);
}

// 实现示例：固定 5% 版税
function royaltyInfo(uint256, uint256 salePrice) external view 
    returns (address receiver, uint256 royaltyAmount) {
    return (artistAddress, salePrice * 500 / 10000);  // 5%
}