# 使用Solidity实现区块链微博

**Published by:** [haoxueren](https://paragraph.com/@haoxueren/)
**Published on:** 2022-12-11
**URL:** https://paragraph.com/@haoxueren/solidity

## Content

// SPDX-License-Identifier: UNDEFINED pragma solidity ^0.8.17; /* * 区块链微博程序 */ contract MicroBlog { address admin; bool is_running = true; string app_name; // 应用程序的名称 uint256 blog_id; // 微博ID，从1开始递增 uint256 blog_count; // 微博数量 uint256[] id_array; // 所有微博ID数组 mapping(uint256 => bool) has_id; // 是否包含当前ID mapping(uint256 => Blog) blogs; // 所有微博集合 event AddBlog(uint256 id, string log); // 发布微博事件 event DeleteBlog(uint256 id, string log); // 删除微博事件 // 微博结构体 struct Blog { uint256 time; address owner; string content; } constructor() payable { admin = msg.sender; } // 设置APP名称 function setAppName(string memory _name) external { app_name = _name; } // 发布一条微博 function addBlog(string memory _content) public isRunning { blog_id++; id_array.push(blog_id); has_id[blog_id] = true; blogs[blog_id] = Blog(block.timestamp, msg.sender, _content); emit AddBlog(blog_id, _content); blog_count++; } // 删除一条微博 function delBlogById(uint256 _id) public canAccess(_id) { if (has_id[_id]) { delete blogs[_id]; delete has_id[_id]; blog_count--; emit DeleteBlog(_id, blogs[_id].content); } } // 根据ID查看微博 function getBlogById(uint256 id) public view returns (Blog memory) { return blogs[id]; } // 查询指定用户的所有微博 function getBlogByAddress(address _address) public view returns (Blog[] memory) { // 计算该用户的微博数量 uint256 _user_count; for (uint256 i = 0; i < id_array.length; i++) { if (has_id[id_array[i]]) { if (blogs[id_array[i]].owner == _address) { _user_count++; } } } // 查询该用户名下的微博 uint256 index; Blog[] memory _blogs = new BlogUnsupported embed; for (uint256 i = 0; i < id_array.length; i++) { if (has_id[id_array[i]]) { if (blogs[id_array[i]].owner == msg.sender) { _blogs[index] = blogs[id_array[i]]; index++; } } } return _blogs; } // 获取所有id function getBlogIds() public view returns (uint256[] memory) { uint256[] memory _result = new uint256Unsupported embed; uint256 index; for (uint256 i = 0; i < id_array.length; i++) { if (has_id[id_array[i]]) { _result[index] = id_array[i]; index++; } } return _result; } // 所有微博数量 function getBlogCount() public view returns (uint256) { return blog_count; } // 设置合约运行状态 function setIsRunning(bool _running) public isAdmin { is_running = _running; } // 变更合约的管理员 function changeOwner(address _newOwner) external { admin = _newOwner; } // 只有合约管理员才可以提取资金 function withdraw(uint256 _amount) public payable isAdmin { payable(admin).transfer(_amount); } // 只有合约管理员才可以提取全部资金 function withdrawAll() public payable isAdmin { payable(admin).transfer(address(this).balance); } // 销毁合约 function destruct() public isAdmin { selfdestruct(payable(admin)); } // 是否为合约管理员 modifier isAdmin() { require(msg.sender == admin, "must be admin!"); _; } // 合约是否在正常运行 modifier isRunning() { require(is_running, "contract is stopped!"); _; } // 用户仅可操作自己的微博(管理员除外) modifier canAccess(uint256 _id) { require( msg.sender == admin || msg.sender == blogs[_id].owner, "permission denied!" ); _; } }

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