用solidity写一个众筹系统要求众筹得到的钱可以被追踪

好的，以下是一个简单的用Solidity编写的众筹合约，其中可以追踪众筹得到的钱：

pragma solidity ^0.8.0;

contract Crowdfunding {
    address public owner;
    uint public goal;
    uint public raisedAmount;
    mapping(address => uint) public contributions;
    bool public goalReached;
    
    event GoalReached(address recipient, uint totalAmountRaised);
    event FundTransfer(address backer, uint amount, bool isContribution);
    
    constructor(uint _goal) {
        owner = msg.sender;
        goal = _goal;
    }
    
    function contribute() public payable {
        require(!goalReached);
        contributions[msg.sender] += msg.value;
        raisedAmount += msg.value;
        emit FundTransfer(msg.sender, msg.value, true);
    }
    
    function checkGoalReached() public {
        require(msg.sender == owner);
        if (raisedAmount >= goal) {
            goalReached = true;
            emit GoalReached(owner, raisedAmount);
        }
    }
    
    function withdraw() public {
        require(goalReached);
        require(msg.sender == owner);
        uint amount = address(this).balance;
        (bool success,) = owner.call{value: amount}("");
        require(success, "Transfer failed.");
        emit FundTransfer(owner, amount, false);
    }
}

在这个合约中，有一个`raisedAmount`变量用于记录众筹得到的总金额，`contributions`映射用于记录每个人的贡献。当众筹成功达成目标时，可以通过`checkGoalReached`函数发出`GoalReached`事件，通知所有人。此时，只有合约的创建者可以通过`withdraw`函数取回筹款。