ERC721开发NFT--接口

使用https://docs.openzeppelin.com/contracts/4.x/erc721中的简单案例

pragma solidity ^0.8.0;

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

contract GameItem is ERC721URIStorage {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    constructor() ERC721("GameItem", "ITM") {}

    function awardItem(address player, string memory tokenURI)
        public
        returns (uint256)
    {
        uint256 newItemId = _tokenIds.current();
        _mint(player, newItemId);
        _setTokenURI(newItemId, tokenURI);

        _tokenIds.increment();
        return newItemId;
    }
}

 

tokenId：类似于商城商品ID，从0开始

approve函数

// 将token授权给to地址
function approve(address to, uint256 tokenId) external;

 

函数：awardItem()   铸造token,

player:拥有者地址

tokenURI：NFT信息，可以是地址或json，
返回tokenId

function awardItem(address player, string memory tokenURI)
        public
        returns (uint256)
    {
        uint256 newItemId = _tokenIds.current();
        _mint(player, newItemId);
        _setTokenURI(newItemId, tokenURI);

        _tokenIds.increment();
        return newItemId;
    }

 

safeTransferFrom函数

// 转移token从from到to地址
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;

 

safeTransferFrom函数

// 转移token从from到to地址
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

 

setApprovalForAll函数

// 授权全部token给operate地址
    function setApprovalForAll(address operator, bool _approved) external;

transferFrom函数,//单个NFT转移，与safeTransferFrom()不同之处在于调用者必须自己确认_to地址能正常接收NFT，否则将丢失此NFT

    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //检查 合约调用者是否是token的拥有者或者被授权approve
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner or approved");
        // 转移token
        _transfer(from, to, tokenId);
    }

 

balanceOf函数,返回由_owner 持有的NFTs的数量

// 记录
    function balanceOf(address owner) external view returns (uint256 balance);

 

getApproved函数,查询地址授权（单个NFT）

    // 获取token的approve地址
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
    //  检查token是否存在
        _requireMinted(tokenId);
        return _tokenApprovals[tokenId];
    }

 

isApprovedForAll函数,查询地址授权（所有的NFT）

    // 设置 给operator的授权情况
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

 

ownerOf函数

// 获取token的拥有者地址
    function ownerOf(uint256 tokenId) external view returns (address owner);

supportsInterface函数

    // 是否使用了 ERC721接口
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

 

tokenURI函数

    //  获取tokenURI
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
    //  检查token是否存在
        _requireMinted(tokenId);
   //  获取baseURI
        string memory baseURI = _baseURI();
   
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

 

 

更多接口解析，请看：https://learnblockchain.cn/article/4507#_mint%E5%87%BD%E6%95%B0

    // 是否使用了 ERC721接口    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {        return            interfaceId == type(IERC721).interfaceId ||            interfaceId == type(IERC721Metadata).interfaceId ||            super.supportsInterface(interfaceId);    }