智能合約案例(1)-----永載史冊的結婚證書

參考于https://mp.weixin.qq.com/s/YG1sbWKA8kS8VAT6pIIaBQ

目的

結合Character角色合約與Evidence存證合約打造結婚證書，示范角色合約和存證合約如何使用，

智能合約的開發步驟

1. 角色分析
2. 基于角色的功能設計
3. 編碼實作各個功能

合約結構說明

Character: 見證人合約（作業人員、結婚夫妻）
Evidence: 存證多簽合約
EvidenceFactory: 存證工廠合約
MarriageEvidence: 結婚合約
Roles: 角色合約

1. 角色控制合約

pragma solidity^0.4.25;

import "./Roles.sol";

contract Character{
    using Roles for Roles.Role;
    Roles.Role private _character;
    
    event characterAdded(address amount,string summary);
    event characterRemoved(address amount);
    event characterRevised(address amount,string summary);
    event characterSeeked(address amount);
    
    address owner;
    address[] characters;
    
    
    constructor()public{
        owner = msg.sender;
    }
    
    modifier onlyOwner(){
        require(owner == msg.sender,"Only owner can call");
        _;
    }
    
    function isCharacter(address amount)public view returns(bool){
        return _character.has(amount);
    }
    
    function _addCharacter(address amount,string _summary)internal{
        _character.add(amount,_summary);
        characters.push(amount);
        emit characterAdded(amount,_summary);
    }
    
    function _removeCharacter(address amount)internal{
        _character.remove(amount);
        emit characterRemoved(amount);
    }
    
    function _reviseCharacter(address amount,string _summary)internal{
        _character.revise(amount,_summary);
        emit characterRevised(amount,_summary);
    }
    
    function _seekCharacter(address amount)internal view returns(string){
        return _character.seek(amount);
        emit characterSeeked(amount);
    }
    
    function _removeCharacterByAddress(address amount)internal{
        for (uint i = 0; i < characters.length; i++) {
            if (amount == characters[i])
                for (uint j = i; j < characters.length-1; j++) 
                    characters[j] = characters[j+1];
            characters.length--;
            }
    }   
    
    function addCharacter(address amount,string _summary)public onlyOwner{
        require(!isCharacter(amount),"The character already exist");
        _addCharacter(amount,_summary);
    }
    
    function removeCharacter(address amount)public onlyOwner{
        require(isCharacter(amount),"The character does not exist");
        _removeCharacter(amount);
        _removeCharacterByAddress(amount);
    }
    
    function reviseCharacter(address amount,string _summary)public onlyOwner{
        require(isCharacter(amount),"The character does not exist");
        _reviseCharacter(amount,_summary);
    }
    
    function seekCharacter(address amount)public view returns(string) {
        require(isCharacter(amount),"The character does not exist");
        return _seekCharacter(amount);
    }
    
    function getAllCharater()public view returns(address[]){
        return characters;
    }
    
}

pragma solidity^0.4.25;

library Roles{
    struct Role{
        mapping(address=>bool) bearer;
        mapping(address=>string) summary;
    }
    //判斷角色
    function has(Role storage role,address amount)internal view returns(bool){
        require(amount!=address(0),"Address is zero address");
        return role.bearer[amount];
    }
    //添加角色
    function add(Role storage role,address amount,string _summary)internal{
        require(!has(role,amount),"Address already exists");
        role.bearer[amount] = true;
        role.summary[amount] = _summary;
    }
    //洗掉角色
    function remove(Role storage role,address amount)internal{
        require(has(role,amount),"Address does not exist");
        role.bearer[amount] = false;
    }
    //修改角色
    function revise(Role storage role,address amount,string _summary)internal {
        require(has(role,amount),"Address does not exist");
        role.summary[amount] = _summary;
    }
    //查詢角色
    function seek(Role storage role,address amount)internal view returns(string){
        require(has(role,amount),"Address does not exist");
        return role.summary[amount];
    }
    
}

介面說明
提供了兩個合約：Roles合約，Character合約，其中Character合約是對外服務合約，Roles合約是庫合約，用于資料和邏輯抽象化，

Character合約：對外服務的唯一介面，包含：
?addCharacter(address amount,string summary):管理員進行添加角色操作，amount是添加角色的地址， _summary添加角色的基本資訊
?removeCharacter(address amount): 管理員進行洗掉角色操作，amount是洗掉角色的地址
?reviseCharacter(address amount,string _summary)：管理員進行修改角色資訊操作，amount是修改角色的地址， _summary修改角色的基本資訊 ?seekCharacter(address amount): 任何人都可以進行查詢角色資訊操作，amount是查詢角色的地址
?getAllCharater()：任何人都可以進行查看當前存在的所有角色操作，
?isCharacter(address amount): 任何人都可以進行查看當前地址是否已經被添加為角色，amount是查詢的地址

MarriageEvidence合約

pragma solidity^0.4.25;
import "./EvidenceFactory.sol";
import "./Character.sol";

contract MarriageEvidence is Character{
    address admin;
    address eviContractAddress;
    address eviAddress;
    constructor() public Character{
        admin = msg.sender;
    }
    
    modifier adminOnly{  
        require(msg.sender == admin ,"require admin");
        _;
    }
    
    modifier charactersMustBeAddedFirst{
        require(getAllCharater().length != 0,"It is null");
        _;
    }
    
    modifier signersOnly{
        require(EvidenceFactory(eviContractAddress).verify(msg.sender),"you not is signer");
        _;
    }
    function deployEvi() external adminOnly charactersMustBeAddedFirst{
        addCharacter(msg.sender,"民政局");
        EvidenceFactory evi = new EvidenceFactory(getAllCharater());
        eviContractAddress = address(evi);
    }
    
    function getSigners() public constant returns(address[]){
        return EvidenceFactory(eviContractAddress).getSigners();
    }
    
    function newEvi(string _evi)public adminOnly returns(address){
        eviAddress = EvidenceFactory(eviContractAddress).newEvidence(_evi);
        return eviAddress;
    }
    
    function sign() public signersOnly returns(bool) {
            return EvidenceFactory(eviContractAddress).addSignatures(eviAddress);
    }
    function getEvi() public constant returns(string,address[],address[]){
            return EvidenceFactory(eviContractAddress).getEvidence(eviAddress);
    }
}

結婚證書簽發流程

1. 部署 MarriageEvidence 合約

民政局管理員wzl呼叫部署合約

2. 呼叫添加角色介面

民政局管理員wzl呼叫方法：

添加丈夫地址：0xb2bb841d09c9e0ff82eee353715197e046c9684c 添加丈夫資訊：
{
“name”:“Alice”,
“url”:“https://blog.csdn.net/weixin_43402353”,
“id”:321183200007270010,
“sex”:“male”,
“address”:{
“street”:“科技 園路.”,
“city”:“江蘇蘇州”,
“country”:“中國”
}
}
添加妻子地址：0x336c9a9d34c3dca40f8a0ac9573b45fa576b07a3 添加妻子資訊：
{
“name”:“Bob”,
“url”:“https://blog.csdn.net/weixin_43402353”,
“id”:321183200007270010,
“sex”:“male”,
“address”:{
“street”:“科技 園路.”,
“city”:“江蘇蘇州”,
“country”:“中國”
}
}

3. 呼叫查看資訊介面
   
   
4. 部署存證合約

呼叫 deployEvi 方法，

5. 創建結婚證書

本質上是支持多簽的一條存證，

6. 呼叫sign介面，夫妻分別簽名
   
7. 呼叫getEvi查看證書