手把手教你區(qū)塊鏈java開發(fā)智能合約nft-第五篇（鑄造第一個NFT）

回顧

初學(xué)區(qū)塊鏈，那真叫一個痛苦并無助。如果沒有人帶你的話

今天寫的這篇是在前面文章基礎(chǔ)上寫的，初學(xué)區(qū)塊鏈的朋友建議先看我前面寫的文章
手把手教你區(qū)塊鏈java開發(fā)智能合約nft-第一篇
手把手教你區(qū)塊鏈java開發(fā)智能合約nft-第二篇（部署第一個NFT智能合約）
手把手教你區(qū)塊鏈java開發(fā)智能合約nft token-第三篇（部署token）
手把手教你區(qū)塊鏈java開發(fā)智能合約nft（第四篇）-如何動態(tài)獲取gasPrice和gasLimit？

部署NFT721

關(guān)于部署NFT721 ，可以參考之前的文章：
手把手教你區(qū)塊鏈java開發(fā)智能合約nft-第二篇（部署第一個NFT智能合約）

部署完成后，將得到一個NFT721的智能合約地址：contractAddress，這個智能合約地址值需要保存好，待會鑄造NFT時需要用到它

比如我在部署合約完成后，得到的contractAddress值為：0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255

鑄造NFT

鑄造NFT也是比較簡單的，直接調(diào)用NFT721 的方法mint 就可以了，主要難點(diǎn)是在對數(shù)據(jù)的簽名上
直接上代碼吧

 @Test
    public void mint() throws Exception {
        //NFT721合約地址
        String contractAddress="0x1fc51bf18b49d29f7a40825914e8c68f4ce7b255";
        String tokenId="2";   //上鏈的NFT id
        String tokenURI="/static/uploadQmVJoMsgcsCCz75ZHzup7e8boqhBz9R8SKYwKknFEWamzA.png";   //上鏈的tokenId對應(yīng)的值
        //鑄造NFT需要用到的私鑰，在部署合約時指定的地址對應(yīng)的私鑰
        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());
    }

關(guān)鍵代碼說明：

• 首先定義了一些傳入的參數(shù)，這里當(dāng)做局部變量定義出來
• 加載智能合約NFT721對象，要用這個對象來調(diào)用mint鑄造NFT

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

• 對上鏈數(shù)據(jù)進(jìn)行簽名

//利用簽名賬戶對應(yīng)的私鑰對上鏈的tokenId等數(shù)據(jù)進(jìn)行簽名
 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);

• 鑄造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方法參數(shù)說明：
public RemoteFunctionCall mint(BigInteger tokenId, BigInteger v, byte[] r, byte[] s, List _fees, String tokenURI)

tokenId:上鏈的tokenId,或者可以理解為NFT的id，必須保證在鏈上唯一
v: 簽名數(shù)據(jù)的v
r:簽名數(shù)據(jù)的R
s:簽名數(shù)據(jù)的S
_fees: （我也不太理解具體是什么）從字面上理解是費(fèi)用信息，

Fee構(gòu)造方法需要傳入兩個參數(shù)：
public Fee(String recipient, BigInteger value) {
super(new Address(recipient),
new Uint256(value));
this.recipient = recipient;
this.value = value;
}
從命名上看：
recipient ： 接受者
value：費(fèi)用

tokenURI：tokenURI，具體上鏈的數(shù)據(jù)，上鏈后可以通過tokenId查看的數(shù)據(jù)，一個tokenId需要指定一個tokenURI

執(zhí)行完以上代碼，沒有報錯的話，等一會就會鑄造成功了
這樣就完成了NFT的鑄造了文章來源地址http://www.zghlxwxcb.cn/news/detail-401993.html

根據(jù)tokenId查看NFT鏈上數(shù)據(jù)

    @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);
    }

完整代碼

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";
        //私鑰
        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 () {
    //這個Web3Util 是自己定義的工具，能根據(jù)userId和siteId生成Credentials 對象的工具，大家可以自己構(gòu)造，我這個有其他依賴，不方便提供源碼
        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 相關(guān)智能合約源碼下載

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