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虚拟货币怎么上合约

2023-05-19 08:56:34 币百科 阅读 0

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首先,我们要有自己的智能合约,我们使用测试网络(ropsten),还要有自己开发编号。申请如下:

地址:https://infura.io/

注册登录,创建自己的项目

java使用web3j链接自己智能合约(教程)

注意:选择测试ropsten链,复制自己的链接 web3j需要用到。

java使用web3j链接自己智能合约(教程)

第二步:使用solidity编译自己的智能合约(个人理解就是链上的服务器脚本),为了案例的丰富性和实用性,全方位的展示web3j调度性,我们使用留言版智能合约模板,solidity代码如下(采用了8.15编译):

// SPDX-License-Identifier: MITpragma solidity ^0.8.0;//声明一个结构体用于留言保持struct Message{    string word;    address from;    string timeStr;}contract Test_Web3j{    Message[] public AllMsg;    //构造方法    constructor (){    }    //接受留言    function setWord(string memory sendMsgStr,string memory tStr)public returns(uint256){        AllMsg.push(Message({word:sendMsgStr,from:msg.sender,timeStr:tStr}));        return AllMsg.length;    }    //查询留言    function getWord() public view returns(uint256,string memory,address,string memory){        if(AllMsg.length==0){         //当没有留言数据时候,返回空          return (0,"",address(0),"");        }else{                                   //当有留言时候,返回最新的一条          uint256 indexInt=AllMsg.length-1;          Message storage thisMsg=AllMsg[indexInt];          return (AllMsg.length,thisMsg.word,thisMsg.from,thisMsg.timeStr);        }    }    //返回总留言的条数    function getSize() public view returns(uint256){      return AllMsg.length;    }    //测试方法1    function testStr() public pure returns(string memory){       return "hello word";    }    function testInt(uint256 argInt) public pure returns(uint256){       return argInt+10;    }}

采用remix在线版发布合约,注意浏览器中需要安装metaMask;才需要ropsten有测试币

java使用web3j链接自己智能合约(教程)

第三步 java部分

import java.math.BigInteger;import java.util.Arrays;import java.util.List;import org.web3j.abi.FunctionEncoder;import org.web3j.abi.FunctionReturnDecoder;import org.web3j.abi.datatypes.Function;import org.web3j.abi.datatypes.Utf8String;import org.web3j.abi.datatypes.Address;import org.web3j.abi.datatypes.generated.Uint256;import org.web3j.crypto.Credentials;import org.web3j.crypto.RawTransaction;import org.web3j.crypto.TransactionEncoder;import org.web3j.protocol.Web3j;import org.web3j.protocol.core.DefaultBlockParameterName;import org.web3j.protocol.core.methods.request.Transaction;import org.web3j.protocol.core.methods.response.EthCall;import org.web3j.protocol.core.methods.response.EthGetBalance;import org.web3j.protocol.core.methods.response.EthSendTransaction;import org.web3j.protocol.http.HttpService;import org.web3j.abi.datatypes.Type;import org.web3j.abi.TypeReference;import org.web3j.tx.Contract;import org.web3j.utils.Convert;import org.web3j.utils.Numeric;public class mainCreateSolitidyJava {    public static void main(String[] args) {        try {            String url = "https://ropsten.infura.io/v3/8ac1e3ea********7a4a077c0a0745";            String contractAddress="0x954e9A986467861********F5aEa8b83cAB63B6";                        //合约地址            String fromAddr="0xb4377fb04FE5aDe3C35*******0cd354308807bF";                               //查询用户地址            String inputPrivateKey="4369ceac05601**************a29f2ab6a41e7c6f93f3ea55222c5d";  //该账号密钥            //查询一下自己虚拟币的数量            Web3j web3j = Web3j.build(new HttpService(url));            //第二个参数:区块的参数,建议选最新区块            EthGetBalance balance = web3j.ethGetBalance(fromAddr, DefaultBlockParameterName.LATEST).send();            String blanceETH = Convert.fromWei(balance.getBalance().toString(), Convert.Unit.ETHER).toPlainString();//.concat(" ether");            System.out.println("====> 拥有的以太坊币 :" + blanceETH);            //测试调用方法一            try {                List input = Arrays.asList();                                               //输入参数                List output = Arrays.asList(new TypeReference<Utf8String>() {});            //接受返回参数                String methodName = "testStr";                Function function = new Function(methodName, input, output);                String data = FunctionEncoder.encode(function);                Transaction transaction = Transaction.createEthCallTransaction(fromAddr, contractAddress, data);                EthCall ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).sendAsync().get();                List<Type> results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());                System.out.println("==111==>"+results.get(0).getValue());            }catch (Exception e){                e.printStackTrace();            }            //测试调用方法二            try {                List input = Arrays.asList(new Uint256(100));                List output = Arrays.asList(new TypeReference<Uint256>() {});                String methodName = "testInt";                Function function = new Function(methodName, input, output);                String data = FunctionEncoder.encode(function);                Transaction transaction = Transaction.createEthCallTransaction(fromAddr, contractAddress, data);                EthCall ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).sendAsync().get();                List<Type> results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());                System.out.println("==222==>"+results.get(0).getValue());            }catch (Exception e){                e.printStackTrace();            }            //测试调用方法三            try {                List input = Arrays.asList(new Utf8String("第一条留言"),new Utf8String("这是插入时间"));                List output = Arrays.asList(new TypeReference<Uint256>() {});                String methodName = "setWord";                Function function = new Function(methodName, input, output);                String encodedFunction = FunctionEncoder.encode(function);                BigInteger nonce =NormalUtil.getNonce(web3j,fromAddr);        //获取nonce                BigInteger gasPrice = NormalUtil.requestCurrentGasPrice(web3j);     //gas数                BigInteger gasLimit = Contract.GAS_LIMIT;                           //限制gas数                RawTransaction rawTransaction = RawTransaction.createTransaction(nonce, gasPrice, gasLimit, contractAddress, encodedFunction);                Credentials credentials = Credentials.create(inputPrivateKey);                byte[] signMessage = TransactionEncoder.signMessage(rawTransaction, credentials);                String hexValue = Numeric.toHexString(signMessage);                EthSendTransaction  ethResult=web3j.ethSendRawTransaction(hexValue).sendAsync().get();                System.out.println("交易编号:"+ethResult.getTransactionHash());            }catch (Exception e){                e.printStackTrace();            }            //获得总留言数量            try {                List input = Arrays.asList();                List ouput = Arrays.asList(new TypeReference<Uint256>() {});                String methodName = "getSize";                Function function = new Function(methodName, input, ouput);                String data = FunctionEncoder.encode(function);                Transaction transaction = Transaction.createEthCallTransaction(fromAddr, contractAddress, data);                EthCall ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).sendAsync().get();                List<Type> results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());                System.out.println("==333==>"+results.get(0).getValue());            }catch (Exception e){                e.printStackTrace();            }            //调用自己合约地址            try {                List input = Arrays.asList();                List ouput = Arrays.asList(new TypeReference<Uint256>(){},new TypeReference<Utf8String>() {},new TypeReference<Address>() {},new TypeReference<Utf8String>() {});                String methodName = "getWord";                Function function = new Function(methodName, input, ouput);                String data = FunctionEncoder.encode(function);                Transaction transaction = Transaction.createEthCallTransaction(fromAddr, contractAddress, data);                EthCall ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).sendAsync().get();                //System.out.println(ethCall.getValue());                List<Type> results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());                System.out.println("==444==>"+results.get(1).getValue());            }catch (Exception e){                e.printStackTrace();            }        }catch (Exception e){            e.printStackTrace();        }    }}

Java部分核心难度地方:ethCall和ethSendRawTransaction区别,ethcall调用的方法是不需要gas费用,而ethSendRawTransaction需要,因此此教程中,插入留言就需要使用ethSendRawTransaction方法来调用。

运行结果如下:

java使用web3j链接自己智能合约(教程)

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