Aptos Move DeFi 实战：从零构建流动性池兑换逻辑
- 寻月隐君
- 发布于 10小时前
- 阅读 71
AptosMoveDeFi实战：从零构建流动性池兑换逻辑去中心化交易所（DEX）是DeFi生态的基石，而其核心正是流动性池背后的自动做市商（AMM）算法。对于有志于在Aptos上构建DeFi应用的开发者来说，亲手实现并验证一个兑换（Swap）功能，是理解其底层机制的最佳路径。本
Aptos Move DeFi 实战：从零构建流动性池兑换逻辑
去中心化交易所（DEX）是 DeFi 生态的基石，而其核心正是流动性池背后的自动做市商（AMM）算法。对于有志于在 Aptos 上构建 DeFi 应用的开发者来说，亲手实现并验证一个兑换（Swap）功能，是理解其底层机制的最佳路径。
本文将摒弃复杂的理论，以最“实事求是”的方式，带你深入 Aptos Move 的开发实践。我们将从一个最基础的恒定乘积公式入手，一步步构建一个包含手续费的兑换计算函数，然后将其扩展为一个可管理多个交易对的模块化结构，并最终分析交易对价格产生的冲击。每一步，我们都将通过严格的单元测试来验证代码的准确性。
实操
Aptos Move Liquidity Pool Calculator
示例一
module net2dev_addr::Sample9 {
/// Error code indicating that the provided amount is not enough for the swap.
const E_NOT_ENOUGH: u64 = 0;
const Pool1_n2dr: u64 = 312;
const Pool1_usdt: u64 = 3201;
fun calculate_swap(coin1: u64, coin2: u64, coin1_amount: u64): u64 {
assert!(coin1_amount > 0, E_NOT_ENOUGH);
let fee = coin1_amount * 5 / 100;
let mix_supply = coin1 * coin2;
let new_usdt = coin1 + coin1_amount;
let new_n2dr = mix_supply / (new_usdt - fee);
let receive = coin2 - new_n2dr;
receive
}
#[test_only]
use std::debug::print;
#[test]
fun test_function() {
let swap_amount = 495; // USDT to swap
let receive = calculate_swap(Pool1_usdt, Pool1_n2dr, swap_amount);
print(&receive);
assert!(receive == 41, 1);
}
/*
Liquidity Pool
Coin1 = 3201 USDT
Coin2 = 312 N2DR
495 USDT -> N2DR
FORMULA with 5% fee
Value1 = Apply a 5% fee to the USDT amount to be swapped.
Fee: 495 * 5 / 100 = 24.75
Value2 = Multiply both USDT and N2DR Supply.
MixSupply: Coin1 * Coin2 = 998,712
Value3 = Determine the new supply of USDT after the swap.
NewUSDT = Coin1 + 495 = 3201 + 495 = 3696
Value4 = Determine the new supply of N2DR after the swap.
NewN2DR = MixSupply / (NewUSDT - fee) = 998,712 / (3696 - 24.75) = 271.5879458
Value5 = Determine the amount of N2DRs to transfer to the user.
Transfer = Coin2 - NewN2DR = 312 - 271.5879458 = 40.4120542
*/
}
这段 Aptos Move 代码通过一个名为 Sample9 的模块，演示了一个简化的去中心化交易所（DEX）中流动性池的兑换计算逻辑。其核心功能 calculate_swap 函数实现了一种自动做市商（AMM）的定价公式：它采用恒定乘积模型（x * y = k），在计算中扣除了 5% 的手续费，并最终算出用户用一种代币能够换取另一种代币的数量。该模块使用常量来模拟一个 USDT/N2DR 交易对的初始流动性状态，并通过一个单元测试来验证整个兑换算法，该测试模拟了一笔 495 USDT 的交易，并用 assert! 断言其兑换结果是否等于预期的 41 N2DR。
测试
➜ aptos move test
INCLUDING DEPENDENCY AptosFramework
INCLUDING DEPENDENCY AptosStdlib
INCLUDING DEPENDENCY MoveStdlib
BUILDING my-dapp
Running Move unit tests
[debug] 41
[ PASS ] 0x48daaa7d16f1a59929ece03157b8f3e4625bc0a201988ac6fea9b38f50db5ef3::Sample9::test_function
Test result: OK. Total tests: 1; passed: 1; failed: 0
{
"Result": "Success"
}
这个测试结果表明，你的 my-dapp 项目已成功通过了其单元测试。在成功编译项目后，测试框架执行了 Sample9 模块中定义的唯一一个测试函数 test_function。日志中的 [debug] 41 是 calculate_swap 函数在接收到测试参数后实际计算并返回的最终兑换数量。紧随其后的 [ PASS ] 状态确认了该测试用例顺利完成，这意味着代码中的 assert! 断言成功地验证了计算结果 41 与预期值完全一致。最后的 Test result: OK 总结陈述为这次测试画上了圆满的句号，证明了你合约中的兑换算法逻辑根据该测试场景是正确无误的。
示例二
module net2dev_addr::Sample9 {
/// Error code indicating that the provided amount is not enough for the swap.
const E_NOT_ENOUGH: u64 = 0;
const N2DR: u64 = 1;
const APT: u64 = 2;
const WETH: u64 = 3;
const Pool1_n2dr: u64 = 312;
const Pool1_usdt: u64 = 3201;
const N2DR_name: vector<u8> = b"N2DR Rewards";
const Pool2_apt: u64 = 21500;
const Pool2_usdt: u64 = 124700;
const APT_name: vector<u8> = b"Aptos";
const Pool3_weth: u64 = 1310;
const Pool3_usdt: u64 = 2750000;
const WETH_name: vector<u8> = b"Wrapped Ether";
fun get_supply(coin_symbol: u64): (u64, u64, vector<u8>) {
if (coin_symbol == N2DR) {
(Pool1_usdt, Pool1_n2dr, N2DR_name)
} else if (coin_symbol == APT) {
(Pool2_usdt, Pool2_apt, APT_name)
} else {
(Pool3_usdt, Pool3_weth, WETH_name)
}
}
// This applies a 5% fee to each swap tx.
fun calculate_swap(coin1: u64, coin2: u64, coin1_amount: u64): u64 {
assert!(coin1_amount > 0, E_NOT_ENOUGH);
let fee = coin1_amount * 5 / 100;
let mix_supply = coin1 * coin2;
let new_usdt = coin1 + coin1_amount;
let new_n2dr = mix_supply / (new_usdt - fee);
let receive = coin2 - new_n2dr;
receive
}
#[test_only]
use std::debug::print;
use std::string::utf8;
#[test]
fun test_function() {
let swap_amount = 495; // USDT to swap
let receive = calculate_swap(Pool1_usdt, Pool1_n2dr, swap_amount);
print(&receive);
assert!(receive == 41, 1);
let (coin1, coin2, name) = get_supply(N2DR);
print(&coin1);
print(&coin2);
assert!(coin1 == Pool1_usdt, 2);
assert!(coin2 == Pool1_n2dr, 3);
assert!(name == N2DR_name, 4);
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
assert!(result == receive, 5);
let (coin1, coin2, name) = get_supply(APT);
print(&coin1);
print(&coin2);
assert!(coin1 == Pool2_usdt, 6);
assert!(coin2 == Pool2_apt, 7);
assert!(name == APT_name, 8);
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
assert!(result == 81, 9);
let (coin1, coin2, name) = get_supply(WETH);
print(&coin1);
print(&coin2);
assert!(coin1 == Pool3_usdt, 10);
assert!(coin2 == Pool3_weth, 11);
assert!(name == WETH_name, 12);
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
assert!(result == 1, 13);
}
/*
Liquidity Pool
Coin1 = 3201 USDT
Coin2 = 312 N2DR
495 USDT -> N2DR
FORMULA with 5% fee
Value1 = Apply a 5% fee to the USDT amount to be swapped.
Fee: 495 * 5 / 100 = 24.75
Value2 = Multiply both USDT and N2DR Supply.
MixSupply: Coin1 * Coin2 = 998,712
Value3 = Determine the new supply of USDT after the swap.
NewUSDT = Coin1 + 495 = 3201 + 495 = 3696
Value4 = Determine the new supply of N2DR after the swap.
NewN2DR = MixSupply / (NewUSDT - fee) = 998,712 / (3696 - 24.75) = 271.5879458
Value5 = Determine the amount of N2DRs to transfer to the user.
Transfer = Coin2 - NewN2DR = 312 - 271.5879458 = 40.4120542
*/
}
这段 Aptos Move 代码在前一个兑换计算示例的基础上进行了扩展，用于模拟一个拥有多个流动性池的去中心化交易所 (DEX)。该模块通过常量定义了三个独立的流动性池（分别是 USDT 与 N2DR、APT 和 WETH 的交易对），并引入了一个新的分派函数 get_supply，该函数能根据传入的代币标识返回对应池子的储备金数据。原有的 calculate_swap 函数被复用，以处理所有这些池子的兑-换计算。整个系统的正确性由一个全面的单元测试来验证，该测试依次获取并验证每个池子的数据，然后对每个池子执行兑换计算并断言其输出结果的正确性，从而展示了一种更模块化和可扩展的多交易对处理方法。
测试
➜ aptos move test
INCLUDING DEPENDENCY AptosFramework
INCLUDING DEPENDENCY AptosStdlib
INCLUDING DEPENDENCY MoveStdlib
BUILDING my-dapp
Running Move unit tests
[debug] 41
[debug] 3201
[debug] 312
[debug] "Swap USDT for:"
[debug] "N2DR Rewards"
[debug] 41
[debug] 124700
[debug] 21500
[debug] "Swap USDT for:"
[debug] "Aptos"
[debug] 81
[debug] 2750000
[debug] 1310
[debug] "Swap USDT for:"
[debug] "Wrapped Ether"
[debug] 1
[ PASS ] 0x48daaa7d16f1a59929ece03157b8f3e4625bc0a201988ac6fea9b38f50db5ef3::Sample9::test_function
Test result: OK. Total tests: 1; passed: 1; failed: 0
{
"Result": "Success"
}这个测试结果表明，你的 my-dapp 项目已成功通过了其全面的单元测试。在成功编译项目后，测试框架执行了 Sample9 模块中定义的唯一但包含了多个步骤的测试函数 test_function。日志中详细的 [debug] 输出，依次展示了针对 N2DR、Aptos 和 Wrapped Ether 这三个不同流动性池的验证过程：它首先打印出池子的储备金数据，然后打印出模拟兑换后计算出的结果（分别为 41、81 和 1）。最终的 [ PASS ] 状态确认了该测试函数顺利完成，意味着其内部所有 assert! 断言均已满足，既验证了 get_supply 函数能为每个池子返回正确数据，也验证了 calculate_swap 函数对每个池子的计算结果都准确无误。
示例三
module net2dev_addr::Sample9 {
/// Error code indicating that the provided amount is not enough for the swap.
const E_NOT_ENOUGH: u64 = 0;
const N2DR: u64 = 1;
const APT: u64 = 2;
const WETH: u64 = 3;
const Pool1_n2dr: u64 = 312;
const Pool1_usdt: u64 = 3201;
const N2DR_name: vector<u8> = b"N2DR Rewards";
const Pool2_apt: u64 = 21500;
const Pool2_usdt: u64 = 124700;
const APT_name: vector<u8> = b"Aptos";
const Pool3_weth: u64 = 1310;
const Pool3_usdt: u64 = 2750000;
const WETH_name: vector<u8> = b"Wrapped Ether";
fun get_supply(coin_symbol: u64): (u64, u64, vector<u8>) {
if (coin_symbol == N2DR) {
(Pool1_usdt, Pool1_n2dr, N2DR_name)
} else if (coin_symbol == APT) {
(Pool2_usdt, Pool2_apt, APT_name)
} else {
(Pool3_usdt, Pool3_weth, WETH_name)
}
}
fun token_price(coin1: u64, coin2: u64): u64 {
assert!(coin1 > 0, E_NOT_ENOUGH);
assert!(coin2 > 0, E_NOT_ENOUGH);
coin1 / coin2
}
// This applies a 5% fee to each swap tx.
fun calculate_swap(coin1: u64, coin2: u64, coin1_amount: u64): u64 {
assert!(coin1_amount > 0, E_NOT_ENOUGH);
let fee = coin1_amount * 5 / 100;
let mix_supply = coin1 * coin2;
let new_usdt = coin1 + coin1_amount;
let new_n2dr = mix_supply / (new_usdt - fee);
let receive = coin2 - new_n2dr;
receive
}
#[test_only]
use std::debug::print;
#[test_only]
use std::string::utf8;
#[test]
fun test_function() {
let swap_amount = 495; // USDT to swap
let receive = calculate_swap(Pool1_usdt, Pool1_n2dr, swap_amount);
print(&receive);
assert!(receive == 41, 1);
let (coin1, coin2, name) = get_supply(N2DR);
print(&coin1);
print(&coin2);
assert!(coin1 == Pool1_usdt, 2);
assert!(coin2 == Pool1_n2dr, 3);
assert!(name == N2DR_name, 4);
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
assert!(result == receive, 5);
let (coin1, coin2, name) = get_supply(APT);
print(&coin1);
print(&coin2);
assert!(coin1 == Pool2_usdt, 6);
assert!(coin2 == Pool2_apt, 7);
assert!(name == APT_name, 8);
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
assert!(result == 81, 9);
let (coin1, coin2, name) = get_supply(WETH);
print(&coin1);
print(&coin2);
assert!(coin1 == Pool3_usdt, 10);
assert!(coin2 == Pool3_weth, 11);
assert!(name == WETH_name, 12);
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
assert!(result == 1, 13);
}
#[test]
fun test_function2() {
let (coin1, coin2, name) = get_supply(N2DR);
let swap_amount = 512; // USDT to swap
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
print(&utf8(b"Token Price Before Swap:"));
let price_before = token_price(coin1, coin2);
print(&price_before);
let result = calculate_swap(coin1, coin2, swap_amount);
print(&result);
print(&utf8(b"Token Price After Swap:"));
let coin1_after = coin1 + swap_amount;
let coin2_after = coin2 - result;
let price_after = token_price(coin1_after, coin2_after);
print(&price_after);
assert!(price_after > price_before, 13);
let (coin1, coin2, name) = get_supply(APT);
let swap_amount = 2340; // USDT to swap
print(&utf8(b"Swap USDT for:"));
print(&utf8(name));
print(&utf8(b"Token Price Before Swap:"));
let price_before = token_price(coin1, coin2);
print(&price_before);
let result = calculate_swap(coin1, coin2, swap_amount);
print(&utf8(b"Swap Result:"));
print(&result);
print(&utf8(b"Token Price After Swap:"));
let coin1_after = coin1 + swap_amount;
let coin2_after = coin2 - result;
let price_after = token_price(coin1_after, coin2_after);
print(&price_after);
}
/*
Liquidity Pool
Coin1 = 3201 USDT
Coin2 = 312 N2DR
495 USDT -> N2DR
FORMULA with 5% fee
Value1 = Apply a 5% fee to the USDT amount to be swapped.
Fee: 495 * 5 / 100 = 24.75
Value2 = Multiply both USDT and N2DR Supply.
MixSupply: Coin1 * Coin2 = 998,712
Value3 = Determine the new supply of USDT after the swap.
NewUSDT = Coin1 + 495 = 3201 + 495 = 3696
Value4 = Determine the new supply of N2DR after the swap.
NewN2DR = MixSupply / (NewUSDT - fee) = 998,712 / (3696 - 24.75) = 271.5879458
Value5 = Determine the amount of N2DRs to transfer to the user.
Transfer = Coin2 - NewN2DR = 312 - 271.5879458 = 40.4120542
*/
}
这段 Aptos Move 代码定义了一个名为 Sample9 的模块，它模拟了一个功能有所增强的多池去中心化交易所（DEX）。在原有的 calculate_swap 和 get_supply 函数基础上，该模块新增了一个简单的 token_price 价格计算函数，用于通过基础除法来估算池中两种代币的相对价格。其单元测试也扩展为了两个独立的函数：第一个 test_function 负责验证在所有三个预定义流动性池（USDT 分别与 N2DR、APT 和 WETH 配对）中的兑换计算是否准确；而新增的 test_function2 则演示了更完整的兑换分析，它通过在模拟交易前后分别调用 token_price 函数，来展示单笔交易对流动性池价格产生的冲击，并断言价格如预期般发生了变化。
测试
➜ aptos move test
INCLUDING DEPENDENCY AptosFramework
INCLUDING DEPENDENCY AptosStdlib
INCLUDING DEPENDENCY MoveStdlib
BUILDING my-dapp
Running Move unit tests
[debug] 41
[debug] 3201
[debug] 312
[debug] "Swap USDT for:"
[debug] "N2DR Rewards"
[debug] 41
[debug] 124700
[debug] 21500
[debug] "Swap USDT for:"
[debug] "Aptos"
[debug] 81
[debug] 2750000
[debug] 1310
[debug] "Swap USDT for:"
[debug] "Wrapped Ether"
[debug] 1
[ PASS ] 0x48daaa7d16f1a59929ece03157b8f3e4625bc0a201988ac6fea9b38f50db5ef3::Sample9::test_function
[debug] "Swap USDT for:"
[debug] "N2DR Rewards"
[debug] "Token Price Before Swap:"
[debug] 10
[debug] 42
[debug] "Token Price After Swap:"
[debug] 13
[debug] "Swap USDT for:"
[debug] "Aptos"
[debug] "Token Price Before Swap:"
[debug] 5
[debug] "Swap Result:"
[debug] 377
[debug] "Token Price After Swap:"
[debug] 6
[ PASS ] 0x48daaa7d16f1a59929ece03157b8f3e4625bc0a201988ac6fea9b38f50db5ef3::Sample9::test_function2
Test result: OK. Total tests: 2; passed: 2; failed: 0
{
"Result": "Success"
}这个测试结果表明，你的 my-dapp 项目完美地通过了其全部单元测试。在成功编译项目后，测试框架执行了 Sample9 模块中定义的 test_function 和 test_function2 两个测试函数。日志中的 [debug] 输出清晰地展示了两个测试的详细过程：第一个 test_function 的输出验证了在三个不同流动性池中的基础兑换计算结果（41, 81, 1）均准确无误；而第二个 test_function2 的输出则更进一步，它打印出了在两次不同交易中，代币价格交易前（如 10 和 5）和交易后（如 13 和 6）的变化，其 [ PASS ] 状态证明了 assert! 断言成功确认了交易对池子价格产生了预期的冲击。最终 Test result: OK 的总结陈述，证明了你合约中所有的兑换和价格影响逻辑都已通过验证。
总结
恭喜你！通过本篇详尽的实战教程，你不仅成功地在 Aptos Move 中实现了一个功能完备的流动性池兑换逻辑，更重要的是，你掌握了从单一功能到模块化、可扩展系统演进的设计思路。
我们从一个基础的 AMM 公式出发，逐步构建了一个能够处理多个交易对的灵活模块，并学会了如何分析和测试交易行为对池子价格产生的具体影响。最终，测试日志中每一条 [ PASS ] 记录，都是对我们严谨逻辑的最好肯定。
现在，你已经具备了构建 DEX 核心算法的能力，并为在 Aptos DeFi 生态中创造更复杂的金融应用打下了坚实的基础。
参考
本文参与登链社区写作激励计划 ，好文好收益，欢迎正在阅读的你也加入。
