应用场景：

1. 类似 uniswap 去中心化交易所池子合约计算。Uniswap v2 工厂合约计算 pair 合约地址的利用了该特性。但其中需要注意的点是：当我们使用 type(constract).creationCode 时需要注意合约元数据的变化，编译器版本的不同也有可能影响到字节码的变化，具体文档如下。（自行部署 Uniswap 代码时可能遇到该问题）

   https://learnblockchain.cn/docs/solidity/metadata.html#encoding-of-the-metadata-hash-in-the-bytecode

   https://github.com/Uniswap/v2-periphery/blob/master/contracts/libraries/UniswapV2Library.sol

   https://github.com/Uniswap/v2-core/blob/master/contracts/UniswapV2Factory.sol

2. 解决交易所充值账号问题

   如果为每个用户创建一个地址，则私钥的维护是个问题，如果单独的一个合约地址那必须要先先部署（浪费gas）才能看到地址，所以利用地址预测的方式，需要的时候再创建。

示例代码如下：

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

contract Factory {
    // Returns the address of the newly deployed contract
    function deploy(
        address _owner,
        uint _foo,
        bytes32 _salt
    ) public payable returns (address) {
        // This syntax is a newer way to invoke create2 without assembly, you just need to pass salt
        // https://docs.soliditylang.org/en/latest/control-structures.html#salted-contract-creations-create2
        return address(new TestContract{salt: _salt}(_owner, _foo));
    }
}

// This is the older way of doing it using assembly
contract FactoryAssembly {
    event Deployed(address addr, uint salt);

    // 1. Get bytecode of contract to be deployed
    // NOTE: _owner and _foo are arguments of the TestContract's constructor
    function getBytecode(address _owner, uint _foo) public pure returns (bytes memory) {
        bytes memory bytecode = type(TestContract).creationCode;

        return abi.encodePacked(bytecode, abi.encode(_owner, _foo));
    }

    // 2. Compute the address of the contract to be deployed
    // NOTE: _salt is a random number used to create an address
    function getAddress(bytes memory bytecode, uint _salt)
        public
        view
        returns (address)
    {
        bytes32 hash = keccak256(
            abi.encodePacked(bytes1(0xff), address(this), _salt, keccak256(bytecode))
        );

        // NOTE: cast last 20 bytes of hash to address
        return address(uint160(uint(hash)));
    }

    // 3. Deploy the contract
    // NOTE:
    // Check the event log Deployed which contains the address of the deployed TestContract.
    // The address in the log should equal the address computed from above.
    function deploy(bytes memory bytecode, uint _salt) public payable {
        address addr;

        /*
        NOTE: How to call create2

        create2(v, p, n, s)
        create new contract with code at memory p to p + n
        and send v wei
        and return the new address
        where new address = first 20 bytes of keccak256(0xff + address(this) + s + keccak256(mem[p…(p+n)))
              s = big-endian 256-bit value
        */
        assembly {
            addr := create2(
                callvalue(), // wei sent with current call
                // Actual code starts after skipping the first 32 bytes
                add(bytecode, 0x20),
                mload(bytecode), // Load the size of code contained in the first 32 bytes
                _salt // Salt from function arguments
            )

            if iszero(extcodesize(addr)) {
                revert(0, 0)
            }
        }

        emit Deployed(addr, _salt);
    }
}

contract TestContract {
    address public owner;
    uint public foo;

    constructor(address _owner, uint _foo) payable {
        owner = _owner;
        foo = _foo;
    }

    function getBalance() public view returns (uint) {
        return address(this).balance;
    }
}

应用场景：

1. 类似 uniswap 去中心化交易所池子合约计算。Uniswap v2 工厂合约计算 pair 合约地址的利用了该特性。但其中需要注意的点是：当我们使用 type(constract).creationCode 时需要注意合约元数据的变化，编译器版本的不同也有可能影响到字节码的变化，具体文档如下。（自行部署 Uniswap 代码时可能遇到该问题）

   https://learnblockchain.cn/docs/solidity/metadata.html#encoding-of-the-metadata-hash-in-the-bytecode

   https://github.com/Uniswap/v2-periphery/blob/master/contracts/libraries/UniswapV2Library.sol

   https://github.com/Uniswap/v2-core/blob/master/contracts/UniswapV2Factory.sol

2. 解决交易所充值账号问题

   如果为每个用户创建一个地址，则私钥的维护是个问题，如果单独的一个合约地址那必须要先先部署（浪费gas）才能看到地址，所以利用地址预测的方式，需要的时候再创建。

示例代码如下：

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

contract Factory {
    // Returns the address of the newly deployed contract
    function deploy(
        address _owner,
        uint _foo,
        bytes32 _salt
    ) public payable returns (address) {
        // This syntax is a newer way to invoke create2 without assembly, you just need to pass salt
        // https://docs.soliditylang.org/en/latest/control-structures.html#salted-contract-creations-create2
        return address(new TestContract{salt: _salt}(_owner, _foo));
    }
}

// This is the older way of doing it using assembly
contract FactoryAssembly {
    event Deployed(address addr, uint salt);

    // 1. Get bytecode of contract to be deployed
    // NOTE: _owner and _foo are arguments of the TestContract's constructor
    function getBytecode(address _owner, uint _foo) public pure returns (bytes memory) {
        bytes memory bytecode = type(TestContract).creationCode;

        return abi.encodePacked(bytecode, abi.encode(_owner, _foo));
    }

    // 2. Compute the address of the contract to be deployed
    // NOTE: _salt is a random number used to create an address
    function getAddress(bytes memory bytecode, uint _salt)
        public
        view
        returns (address)
    {
        bytes32 hash = keccak256(
            abi.encodePacked(bytes1(0xff), address(this), _salt, keccak256(bytecode))
        );

        // NOTE: cast last 20 bytes of hash to address
        return address(uint160(uint(hash)));
    }

    // 3. Deploy the contract
    // NOTE:
    // Check the event log Deployed which contains the address of the deployed TestContract.
    // The address in the log should equal the address computed from above.
    function deploy(bytes memory bytecode, uint _salt) public payable {
        address addr;

        /*
        NOTE: How to call create2

        create2(v, p, n, s)
        create new contract with code at memory p to p + n
        and send v wei
        and return the new address
        where new address = first 20 bytes of keccak256(0xff + address(this) + s + keccak256(mem[p…(p+n)))
              s = big-endian 256-bit value
        */
        assembly {
            addr := create2(
                callvalue(), // wei sent with current call
                // Actual code starts after skipping the first 32 bytes
                add(bytecode, 0x20),
                mload(bytecode), // Load the size of code contained in the first 32 bytes
                _salt // Salt from function arguments
            )

            if iszero(extcodesize(addr)) {
                revert(0, 0)
            }
        }

        emit Deployed(addr, _salt);
    }
}

contract TestContract {
    address public owner;
    uint public foo;

    constructor(address _owner, uint _foo) payable {
        owner = _owner;
        foo = _foo;
    }

    function getBalance() public view returns (uint) {
        return address(this).balance;
    }
}