流动性挖矿与质押奖励
了解 DeFi 流动性挖矿和质押奖励合约如何随时间分发代币，包括主要协议使用的每代币奖励记账模式。
流动性挖矿与质押奖励 是 CoddyKit 上的免费 Blockchain Smart Contracts with Solidity 课时。 这是第 4 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Blockchain Smart Contracts with Solidity 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Blockchain Smart Contracts with Solidity 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
What Is Yield Farming?
Yield farming means depositing tokens into a protocol to earn additional token rewards. Users stake an asset, and the protocol distributes a reward token continuously over time to incentivize participation.
The Core Challenge
The hard part is fairly splitting rewards among many stakers who deposit and withdraw at different times, without looping over every user (which would be too gas-expensive).
The solution is the reward-per-token accumulator pattern.
Reward Per Token Idea
Track a single global accumulator: the total reward earned per staked token since the contract started. Each user stores a snapshot of this accumulator at their last interaction.
Their owed reward = stake amount times (current accumulator minus their snapshot).
State Variables
Set up the bookkeeping variables that drive the accounting.
uint256 public rewardRate; // reward tokens per second
uint256 public lastUpdateTime;
uint256 public rewardPerTokenStored;
uint256 public totalStaked;
mapping(address => uint256) public balances;
mapping(address => uint256) public userRewardPerTokenPaid;
mapping(address => uint256) public rewards;Computing Reward Per Token
The accumulator grows by the reward emitted since the last update, divided by the total staked.
function rewardPerToken() public view returns (uint256) {
if (totalStaked == 0) return rewardPerTokenStored;
uint256 elapsed = block.timestamp - lastUpdateTime;
return rewardPerTokenStored + (elapsed * rewardRate * 1e18) / totalStaked;
}Calculating Earned Rewards
A user's earned amount is their balance times the difference between the current accumulator and their last paid snapshot, plus anything already credited.
function earned(address account) public view returns (uint256) {
uint256 diff = rewardPerToken() - userRewardPerTokenPaid[account];
return (balances[account] * diff) / 1e18 + rewards[account];
}The Update Modifier
Before any state-changing action, settle the user's pending rewards and refresh the global accumulator. A modifier keeps this consistent.
modifier updateReward(address account) {
rewardPerTokenStored = rewardPerToken();
lastUpdateTime = block.timestamp;
if (account != address(0)) {
rewards[account] = earned(account);
userRewardPerTokenPaid[account] = rewardPerTokenStored;
}
_;
}Staking Tokens
Staking pulls tokens from the user and increases their balance and the total. The modifier settles rewards first.
function stake(uint256 amount) external updateReward(msg.sender) {
require(amount > 0, 'zero amount');
totalStaked += amount;
balances[msg.sender] += amount;
stakingToken.transferFrom(msg.sender, address(this), amount);
}Withdrawing Stake
Withdrawal mirrors staking: settle rewards, decrease balances, then return the staked tokens.
function withdraw(uint256 amount) external updateReward(msg.sender) {
require(balances[msg.sender] >= amount, 'too much');
totalStaked -= amount;
balances[msg.sender] -= amount;
stakingToken.transfer(msg.sender, amount);
}Claiming Rewards
Claiming sends accrued reward tokens to the user and resets their pending balance to zero.
function getReward() external updateReward(msg.sender) {
uint256 reward = rewards[msg.sender];
if (reward > 0) {
rewards[msg.sender] = 0;
rewardsToken.transfer(msg.sender, reward);
}
}Risks to Watch
Yield farming carries risks: impermanent loss when staking LP tokens, reward token inflation, and contract exploits. Always ensure the contract holds enough reward tokens to cover emissions and audit the math carefully.
Quick Check
Test your understanding of staking rewards.
Recap
You learned the staking rewards pattern used across DeFi:
- A global reward-per-token accumulator
- Per-user snapshots for O(1) accounting
- An
updateRewardmodifier settling state before stake, withdraw, and claim
This pattern fairly distributes continuous rewards while keeping gas costs low.
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在浏览器中编写并运行真实代码，获得全天候 AI 导师的即时帮助，并在网页或应用中继续学习。
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常见问题解答
「流动性挖矿与质押奖励」课时是免费的吗？
是的 — 「流动性挖矿与质押奖励」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Blockchain Smart Contracts with Solidity 课程的其余内容，请升级到 CoddyKit PRO。 Blockchain Smart Contracts with Solidity 课程共包含 4 节课。
「流动性挖矿与质押奖励」这节课中我会学到什么？
了解 DeFi 流动性挖矿和质押奖励合约如何随时间分发代币，包括主要协议使用的每代币奖励记账模式。 你通过在浏览器中直接运行的动手代码来练习 Blockchain Smart Contracts with Solidity，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Blockchain Smart Contracts with Solidity 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Blockchain Smart Contracts with Solidity 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 4 节课，共 4 节。
「流动性挖矿与质押奖励」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Blockchain Smart Contracts with Solidity 课中编写并运行代码吗？
能。每节 Blockchain Smart Contracts with Solidity 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。