手续费抽象

每笔 Solana 交易都需要使用 SOL 支付网络手续费。但用户在使用你的支付应用时，通常希望用稳定币进行交易，而不想管理第二种代币余额。手续费抽象通过让其他人代为支付手续费，消除了这一障碍。

本指南涵盖两个层面：

手续费赞助的工作原理 — Solana 的底层机制
使用 Kora 实现大规模手续费抽象 — 可用于生产环境的手续费抽象服务

手续费赞助的工作原理

Solana 交易有一个指定的手续费支付者——即负责支付网络手续费的账户。默认情况下，这个账户是第一个签名者。但你也可以指定其他账户作为手续费支付者，从而让第三方（即“赞助者”）代表发送方支付手续费。

发送方和赞助者都必须对交易进行签名：

发送方 签名以授权其代币的转账
赞助者 签名以授权支付网络手续费

参见 Solana 支付原理了解核心支付概念。

以下步骤展示了核心流程。完整可运行代码请参见演示。

创建赞助者账户

为将要支付交易手续费的赞助者生成一个独立的 keypair。赞助者需要持有用于支付手续费的 SOL，但无需持有被转账的代币。

Sponsor Transaction Fee

const sponsor = (await generateKeypair()).signer;

创建转账指令

创建以发送方为授权人的代币转账指令。发送方拥有代币，必须对转账进行签名。

Sponsor Transaction Fee

const sponsor = (await generateKeypair()).signer;

const transferInstruction = getTransferInstruction({
  source: senderAta,
  destination: recipientAta,
  authority: sender, // Sender signs for the transfer
  amount: 250_000n // adjusted for the mint's decimals
});

由赞助方作为手续费支付者进行发送

使用 prepareAndSend，同时包含 authority（签署转账的发送方）和 feePayer（支付手续费的赞助方）。两者都必须签署该交易。

Sponsor Transaction Fee

const sponsor = (await generateKeypair()).signer;

const transferInstruction = getTransferInstruction({
  source: senderAta,
  destination: recipientAta,
  authority: sender,
  amount: 250_000n
});

const signature = await client.transaction.prepareAndSend({
  authority: sender, // Signs the transfer instruction
  feePayer: sponsor, // Pays the transaction fees
  instructions: [transferInstruction],
  version: 0
});

创建赞助者账户

为将要支付交易手续费的赞助者生成一个独立的 keypair。赞助者需要持有用于支付手续费的 SOL，但无需持有被转账的代币。

创建转账指令

创建以发送方为授权人的代币转账指令。发送方拥有代币，必须对转账进行签名。

由赞助方作为手续费支付者进行发送

使用 prepareAndSend，同时包含 authority（签署转账的发送方）和 feePayer（支付手续费的赞助方）。两者都必须签署该交易。

Sponsor Transaction Fee

const sponsor = (await generateKeypair()).signer;

演示

Demo



// Generate keypairs for sender, recipient, and sponsor (fee payer)
const sender = (await generateKeypair()).signer;
const recipient = (await generateKeypair()).signer;
const sponsor = (await generateKeypair()).signer;

console.log("Sender Address:", sender.address);
console.log("Recipient Address:", recipient.address);
console.log("Sponsor Address (Fee Payer):", sponsor.address);

// Demo Setup: Create client, mint account, token accounts, and fund with initial tokens
const { client, mint } = await demoSetup(sender, recipient, sponsor);

console.log("\nMint Address:", mint.address);

// Derive the Associated Token Accounts addresses (ATAs) for sender and recipient
const [senderAta] = await findAssociatedTokenPda({
  mint: mint.address,
  owner: sender.address,
  tokenProgram: TOKEN_2022_PROGRAM_ADDRESS
});

const [recipientAta] = await findAssociatedTokenPda({
  mint: mint.address,
  owner: recipient.address,
  tokenProgram: TOKEN_2022_PROGRAM_ADDRESS
});

console.log("Sender Token Account:", senderAta.toString());
console.log("Recipient Token Account:", recipientAta.toString());

// =============================================================================
// Sponsored Token Payment Demo
// =============================================================================

// Create instruction to transfer tokens from sender to recipient
// Transferring 250,000 base units = 0.25 tokens (with 6 decimals)
const transferInstruction = getTransferInstruction({
  source: senderAta,
  destination: recipientAta,
  authority: sender, // Pass signer, not just address
  amount: 250_000n // 0.25 tokens
});

// Prepare and send transaction with sponsor as fee payer using @solana/client
// The sponsor pays transaction fees, sender signs for the transfer
const signature = await client.transaction.prepareAndSend({
  authority: sender, // Sender signs the transfer instruction
  feePayer: sponsor, // Sponsor pays the transaction fees (different account)
  instructions: [transferInstruction],
  version: 0
});

console.log("\n=== Sponsored Token Payment Complete ===");
console.log("Transaction Signature:", signature.toString());

// Fetch final token account balances using @solana/client SPL token helper
const splToken = client.splToken({
  mint: mint.address,
  tokenProgram: "auto"
});

const senderBalance = await splToken.fetchBalance(sender.address);
const recipientBalance = await splToken.fetchBalance(recipient.address);

console.log("\nSender Token Account Balance:", senderBalance);
console.log("Recipient Token Account Balance:", recipientBalance);

// Fetch transaction details
const transaction = await client.runtime.rpc
  .getTransaction(signature, {
    encoding: "jsonParsed",
    maxSupportedTransactionVersion: 0
  })
  .send();

const feePayer = transaction?.transaction.message.accountKeys?.[0];
console.log("\nNote: The first account in accountKeys is always the fee payer");
console.log("Fee Payer Address:", feePayer);

// =============================================================================
// Demo Setup Helper Function
// =============================================================================

Console

Click to execute the code.

Demo



// Generate keypairs for sender, recipient, and sponsor (fee payer)
const sender = (await generateKeypair()).signer;
const recipient = (await generateKeypair()).signer;
const sponsor = (await generateKeypair()).signer;

console.log("Sender Address:", sender.address);
console.log("Recipient Address:", recipient.address);
console.log("Sponsor Address (Fee Payer):", sponsor.address);

// Demo Setup: Create client, mint account, token accounts, and fund with initial tokens
const { client, mint } = await demoSetup(sender, recipient, sponsor);

console.log("\nMint Address:", mint.address);

// Derive the Associated Token Accounts addresses (ATAs) for sender and recipient
const [senderAta] = await findAssociatedTokenPda({
  mint: mint.address,
  owner: sender.address,
  tokenProgram: TOKEN_2022_PROGRAM_ADDRESS
});

const [recipientAta] = await findAssociatedTokenPda({
  mint: mint.address,
  owner: recipient.address,
  tokenProgram: TOKEN_2022_PROGRAM_ADDRESS
});

console.log("Sender Token Account:", senderAta.toString());
console.log("Recipient Token Account:", recipientAta.toString());

// =============================================================================
// Sponsored Token Payment Demo
// =============================================================================

// Create instruction to transfer tokens from sender to recipient
// Transferring 250,000 base units = 0.25 tokens (with 6 decimals)
const transferInstruction = getTransferInstruction({
  source: senderAta,
  destination: recipientAta,
  authority: sender, // Pass signer, not just address
  amount: 250_000n // 0.25 tokens
});

// Prepare and send transaction with sponsor as fee payer using @solana/client
// The sponsor pays transaction fees, sender signs for the transfer
const signature = await client.transaction.prepareAndSend({
  authority: sender, // Sender signs the transfer instruction
  feePayer: sponsor, // Sponsor pays the transaction fees (different account)
  instructions: [transferInstruction],
  version: 0
});

console.log("\n=== Sponsored Token Payment Complete ===");
console.log("Transaction Signature:", signature.toString());

// Fetch final token account balances using @solana/client SPL token helper
const splToken = client.splToken({
  mint: mint.address,
  tokenProgram: "auto"
});

const senderBalance = await splToken.fetchBalance(sender.address);
const recipientBalance = await splToken.fetchBalance(recipient.address);

console.log("\nSender Token Account Balance:", senderBalance);
console.log("Recipient Token Account Balance:", recipientBalance);

// Fetch transaction details
const transaction = await client.runtime.rpc
  .getTransaction(signature, {
    encoding: "jsonParsed",
    maxSupportedTransactionVersion: 0
  })
  .send();

const feePayer = transaction?.transaction.message.accountKeys?.[0];
console.log("\nNote: The first account in accountKeys is always the fee payer");
console.log("Fee Payer Address:", feePayer);

// =============================================================================
// Demo Setup Helper Function
// =============================================================================

Console

Click to execute the code.

当你为终端用户创建 token account 时，他们可以关闭该账户并取回用于 rent 的 SOL。建议向用户收取账户创建费用（如以稳定币结算），或将此成本计入你的产品经济模型中。

使用 Kora 实现大规模手续费抽象

fee payer 原语非常强大，但要构建生产级的免 gas 系统，还需要更多功能：管理赞助钱包、处理 token 兑换（让用户可以用 USDC "支付" 手续费）、限流和安全控制。

Kora 处理了这些复杂性。它是一个 JSON-RPC 服务器，提供手续费抽象，让用户无需 SOL。你可以全额赞助手续费，或接受任何 token 作为手续费支付。

只需一条命令即可部署 Kora：

cargo install kora-cli
kora --config path/to/kora.toml rpc start --signers-config path/to/signers.toml

然后使用 Kora 客户端签名并发送交易：

pnpm add @solana/kora

import { KoraClient } from "@solana/kora";

const kora = new KoraClient({ rpcUrl: "https://your-kora-instance" });

const { signature } = await kora.signAndSendTransaction({
  transaction: base64EncodedTransaction
});