手把手教你区块链java开发智能合约nft-第五篇（铸造第一个NFT）

手把手教你区块链java开发智能合约nft-第五篇（铸造第一个NFT）

回顾

初学区块链，那真叫一个痛苦并无助。如果没有人带你的话

今天写的这篇是在前面文章基础上写的，初学区块链的朋友建议先看我前面写的文章
手把手教你区块链java开发智能合约nft-第一篇
手把手教你区块链java开发智能合约nft-第二篇（部署第一个NFT智能合约）
手把手教你区块链java开发智能合约nft token-第三篇（部署token）
手把手教你区块链java开发智能合约nft（第四篇）-如何动态获取gasPrice和gasLimit？

部署NFT721

关于部署NFT721 ，可以参考之前的文章：
手把手教你区块链java开发智能合约nft-第二篇（部署第一个NFT智能合约）

部署完成后，将得到一个NFT721的智能合约地址：contractAddress，这个智能合约地址值需要保存好，待会铸造NFT时需要用到它

比如我在部署合约完成后，得到的contractAddress值为：0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255

铸造NFT

铸造NFT也是比较简单的，直接调用NFT721 的方法mint 就可以了，主要难点是在对数据的签名上
直接上代码吧

 @Test
    public void mint() throws Exception {
        //NFT721合约地址
        String contractAddress="0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255";
        String tokenId="2";   //上链的NFT id
        String tokenURI="/static/uploadQmVJoMsgcsCCz75ZHzup7e8boqhBz9R8SKYwKknFEWamzA.png";   //上链的tokenId对应的值
        //铸造NFT需要用到的私钥，在部署合约时指定的地址对应的私钥
        String miner="0x5369576889297382912123166219811286283737728368986117127236719812";

        TransactionManager transactionManager = getRawTransactionManager();
        ContractGasProvider contractGasProvider = getContractGasProvider();
        NFT721 nft721 = NFT721.load(contractAddress, web3j, transactionManager, contractGasProvider);
        Credentials credentials = getCredentials();

        ECKeyPair ecKeyPair = ECKeyPair.create(Numeric.hexStringToByteArray(miner));

        Type<BigInteger> tId = new Uint(new BigInteger(tokenId));
        String a = contractAddress + Numeric.cleanHexPrefix(TypeEncoder.encode(tId));
        a = Hash.sha3(a);
        byte[] b = Numeric.hexStringToByteArray(a);
        Sign.SignatureData data = Sign.signPrefixedMessage(b, ecKeyPair);


        ArrayList<NFT721.Fee> fees = Lists.newArrayList(new NFT721.Fee(credentials.getAddress(), BigInteger.valueOf(200)));
        TransactionReceipt transactionReceipt = nft721.mint(new BigInteger(tokenId), new BigInteger(data.getV()), data.getR(), data.getS(),
                fees, tokenURI).send();
        System.out.println("mint:hash::"+transactionReceipt.getTransactionHash());
        System.out.println("mint:getContractAddress::"+transactionReceipt.getContractAddress());
    }

关键代码说明：

• 首先定义了一些传入的参数，这里当做局部变量定义出来
• 加载智能合约NFT721对象，要用这个对象来调用mint铸造NFT

     NFT721 nft721 = NFT721.load(contractAddress, web3j, transactionManager, contractGasProvider);

• 对上链数据进行签名

//利用签名账户对应的私钥对上链的tokenId等数据进行签名
 ECKeyPair ecKeyPair = ECKeyPair.create(Numeric.hexStringToByteArray(miner));

        Type<BigInteger> tId = new Uint(new BigInteger(tokenId));
        String a = contractAddress + Numeric.cleanHexPrefix(TypeEncoder.encode(tId));
        a = Hash.sha3(a);
        byte[] b = Numeric.hexStringToByteArray(a);
        Sign.SignatureData data = Sign.signPrefixedMessage(b, ecKeyPair);

• 铸造NFT

        ArrayList<NFT721.Fee> fees = Lists.newArrayList(new NFT721.Fee(credentials.getAddress(), BigInteger.valueOf(200)));
        TransactionReceipt transactionReceipt = nft721.mint(new BigInteger(tokenId), new BigInteger(data.getV()), data.getR(), data.getS(),
                fees, tokenURI).send();

mint方法参数说明：
public RemoteFunctionCall mint(BigInteger tokenId, BigInteger v, byte[] r, byte[] s, List _fees, String tokenURI)

tokenId:上链的tokenId,或者可以理解为NFT的id，必须保证在链上唯一
v: 签名数据的v
r:签名数据的R
s:签名数据的S
_fees: （我也不太理解具体是什么）从字面上理解是费用信息，

Fee构造方法需要传入两个参数：
public Fee(String recipient, BigInteger value) {
super(new Address(recipient),
new Uint256(value));
this.recipient = recipient;
this.value = value;
}
从命名上看：
recipient ： 接受者
value：费用

tokenURI：tokenURI，具体上链的数据，上链后可以通过tokenId查看的数据，一个tokenId需要指定一个tokenURI

执行完以上代码，没有报错的话，等一会就会铸造成功了
这样就完成了NFT的铸造了

根据tokenId查看NFT链上数据

    @Test
    public void tokenURI() throws Exception {

        String contractAddress="0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255";
        String tokenId="2";
        TransactionManager transactionManager = getRawTransactionManager();
        ContractGasProvider contractGasProvider = getContractGasProvider();
        NFT721 nft721 = NFT721.load(contractAddress, web3j, transactionManager, contractGasProvider);
        String tokenURI = nft721.tokenURI(new BigInteger(tokenId)).send();
        System.out.println("tokenURI::"+tokenURI);
    }

完整代码

package net.sandboxol.support.deploy.mint;

import net.sandboxol.support.deploy.NFT721;
import net.sandboxol.support.utils.Web3Util;
import org.assertj.core.util.Lists;
import org.junit.Test;
import org.web3j.abi.TypeEncoder;
import org.web3j.abi.datatypes.Type;
import org.web3j.abi.datatypes.Uint;
import org.web3j.crypto.Credentials;
import org.web3j.crypto.ECKeyPair;
import org.web3j.crypto.Hash;
import org.web3j.crypto.Sign;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.core.methods.response.TransactionReceipt;
import org.web3j.protocol.http.HttpService;
import org.web3j.tx.RawTransactionManager;
import org.web3j.tx.TransactionManager;
import org.web3j.tx.gas.ContractGasProvider;
import org.web3j.tx.gas.StaticGasProvider;
import org.web3j.utils.Numeric;

import java.io.IOException;
import java.math.BigInteger;
import java.util.ArrayList;

public class DeployMintTest {
    Web3j web3j = Web3j.build(new HttpService("http://192.168.159.101:8545/"));
	private String userId="214158";
    private String siteId="ishow";
    @Test
    public void mint() throws Exception {

        String contractAddress="0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255";
        String tokenId="2";
        String tokenURI="/static/uploadQmVJoMsgcsCCz75ZHzup7e8boqhBz9R8SKYwKknFEWamzA.png";
        //私钥
        String miner="0x5369576889297382912123166219811286283737728368986117127236719812";

        TransactionManager transactionManager = getRawTransactionManager();
        ContractGasProvider contractGasProvider = getContractGasProvider();
        NFT721 nft721 = NFT721.load(contractAddress, web3j, transactionManager, contractGasProvider);
        Credentials credentials = getCredentials();

        ECKeyPair ecKeyPair = ECKeyPair.create(Numeric.hexStringToByteArray(miner));



        Type<BigInteger> tId = new Uint(new BigInteger(tokenId));
        String a = contractAddress + Numeric.cleanHexPrefix(TypeEncoder.encode(tId));
        a = Hash.sha3(a);
        byte[] b = Numeric.hexStringToByteArray(a);
        Sign.SignatureData data = Sign.signPrefixedMessage(b, ecKeyPair);


        ArrayList<NFT721.Fee> fees = Lists.newArrayList(new NFT721.Fee(credentials.getAddress(), BigInteger.valueOf(200)));
        TransactionReceipt transactionReceipt = nft721.mint(new BigInteger(tokenId), new BigInteger(data.getV()), data.getR(), data.getS(),
                fees, tokenURI).send();
        System.out.println("mint:hash::"+transactionReceipt.getTransactionHash());
        System.out.println("mint:getContractAddress::"+transactionReceipt.getContractAddress());
    }


    @Test
    public void tokenURI() throws Exception {

        String contractAddress="0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255";
        String tokenId="1";
        TransactionManager transactionManager = getRawTransactionManager();
        ContractGasProvider contractGasProvider = getContractGasProvider();
        NFT721 nft721 = NFT721.load(contractAddress, web3j, transactionManager, contractGasProvider);
        String tokenURI = nft721.tokenURI(new BigInteger(tokenId)).send();
        System.out.println("tokenURI::"+tokenURI);
    }

    private Credentials getCredentials () {
    //这个Web3Util 是自己定义的工具，能根据userId和siteId生成Credentials 对象的工具，大家可以自己构造，我这个有其他依赖，不方便提供源码
        return Web3Util.getUserCredentials(userId,siteId);
    }

    private TransactionManager getRawTransactionManager() throws IOException {
        BigInteger chainId = web3j.ethChainId().send().getChainId();
        return new RawTransactionManager(web3j, getCredentials(),chainId.longValue());
    }

    private ContractGasProvider getContractGasProvider(){
        return new StaticGasProvider(BigInteger.valueOf(22_000_000_000l),BigInteger.valueOf(6_700_000l));
    }
}

NFT721 相关智能合约源码下载