基于区块链的供应链管理追溯系统研究

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;
 
contract SupplyChain {
    address public owner;
 
    struct Product {
        uint productId;
        string productName;
        address producer;
        address distributor;
        address retailer;
        bool isProduced;
        bool isDistributed;
        bool isSold;
    }
 
    mapping(uint => Product) public products;
    uint public productCount;
 
    constructor() {
        owner = msg.sender;
        productCount = 0;
    }
 
    function produceProduct(string memory _productName) public {
        require(msg.sender == owner, "Only owner can produce products.");
        productCount++;
        products[productCount] = Product(productCount, _productName, msg.sender, address(0), address(0), true, false, false);
    }
 
    function distributeProduct(uint _productId, address _distributor) public {
        require(products[_productId].isProduced == true, "Product does not exist or is not produced yet.");
        require(msg.sender == products[_productId].producer, "Only producer can distribute the product.");
        products[_productId].distributor = _distributor;
        products[_productId].isDistributed = true;
    }
 
    function sellProduct(uint _productId, address _retailer) public {
        require(products[_productId].isDistributed == true, "Product is not distributed yet.");
        require(msg.sender == products[_productId].distributor, "Only distributor can sell the product.");
        products[_productId].retailer = _retailer;
        products[_productId].isSold = true;
    }
}