使用 Java 和 web3j 进行 Token 开发[概述][译]

内容简介：学习使用 web3j 部署ERC20 以及与合约进行交互。本文参与登链社区写作激励计划 ，好文好收益，欢迎正在阅读的你也加入。

truffle compile

curl -L get.web3j.io | sh

Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://raw.githubusercontent.com/web3j/web3j-installer/master/installer.ps1'))

web3j truffle generate Truffle/build/contracts/JavaToken.json -o src -p com.javaToken

// The Ganache TestNet listens at port 7545
Web3j w3 = Web3j.build(new HttpService("HTTP://127.0.0.1:7545"));
String privateKey = "你的私钥";
Credentials credentials = Credentials.create(privateKey);
// 初始发行量
BigInteger initialSupply = BigInteger.valueOf(100000);

JavaToken javaToken = JavaToken.deploy(w3, credentials, new DefaultGasProvider(), initialSupply).send()

// The Ganache TestNet listens at port 7545
Web3j w3 = Web3j.build(new HttpService("HTTP://127.0.0.1:7545"));
String privateKey = "你的私钥";
Credentials credentials = Credentials.create(privateKey);
String contractAddress = "合约地址";

JavaToken javaToken = JavaToken.load(contractAddress,w3,credentials,new DefaultGasProvider());

// With java wrapper
BigInteger balance = javaToken.balanceOf(credentials.getAddress()).send()

// Without java wrapper
String contractAddress = "YourDeployedContractAddress";

// Define the function we want to invoke from the smart contract
Function function = new Function("balanceOf", Arrays.asList(new Address(credentials.getAddress())),
                                 Arrays.asList(new TypeReference<Uint256>() {}));

// Encode it for the contract to understand
String encodedFunction = FunctionEncoder.encode(function);

/*
Send the request and wait for the response using eth call since
it's a read only transaction with no cost associated
*/
EthCall response = w3.ethCall(
  Transaction.createEthCallTransaction(credentials.getAddress(), contractAddress, encodedFunction),
  DefaultBlockParameterName.LATEST).send();

balance = Numeric.toBigInt(response.getValue());

String addressTo = "YourFriendsAddress";
BigInteger amount = BigInteger.valueOf(500);

// 使用 wrapper
TransactionReceipt receipt = javaToken.transfer(addressTo,amount).send();

// Without java wrapper

// 定义想要调用的函数
Function function = new Function("transfer", Arrays.asList(new Address(addressTo), new Uint256(amount)),  Collections.emptyList());

// 编码，以便合约可以理解调用哪个函数
String encodedFunction = FunctionEncoder.encode(function);

/*
Need to use a TransactionManager here since transfer actually alters the state of the blockchain and credentials are therefore relevant
*/
TransactionManager transactionManager = new FastRawTransactionManager(w3, credentials);


// Send the transaction off using transactionManager and wait for the hash
String transactionHash = transactionManager.sendTransaction(DefaultGasProvider.GAS_PRICE,
                                                            DefaultGasProvider.GAS_LIMIT, contractAddress, encodedFunction,
                                                            BigInteger.ZERO).getTransactionHash();

// 获取交易收据
Optional<TransactionReceipt> transactionReceipt =
  w3.ethGetTransactionReceipt(transactionHash).send().getTransactionReceipt();
if(transactionReceipt.isEmpty())
  receipt = null;
else
  receipt = transactionReceipt.get();

truffle compile

curl -L get.web3j.io | sh

Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://raw.githubusercontent.com/web3j/web3j-installer/master/installer.ps1'))

web3j truffle generate Truffle/build/contracts/JavaToken.json -o src -p com.javaToken

// The Ganache TestNet listens at port 7545
Web3j w3 = Web3j.build(new HttpService("HTTP://127.0.0.1:7545"));
String privateKey = "你的私钥";
Credentials credentials = Credentials.create(privateKey);
// 初始发行量
BigInteger initialSupply = BigInteger.valueOf(100000);

JavaToken javaToken = JavaToken.deploy(w3, credentials, new DefaultGasProvider(), initialSupply).send()

// The Ganache TestNet listens at port 7545
Web3j w3 = Web3j.build(new HttpService("HTTP://127.0.0.1:7545"));
String privateKey = "你的私钥";
Credentials credentials = Credentials.create(privateKey);
String contractAddress = "合约地址";

JavaToken javaToken = JavaToken.load(contractAddress,w3,credentials,new DefaultGasProvider());

// With java wrapper
BigInteger balance = javaToken.balanceOf(credentials.getAddress()).send()

// Without java wrapper
String contractAddress = "YourDeployedContractAddress";

// Define the function we want to invoke from the smart contract
Function function = new Function("balanceOf", Arrays.asList(new Address(credentials.getAddress())),
                                 Arrays.asList(new TypeReference<Uint256>() {}));

// Encode it for the contract to understand
String encodedFunction = FunctionEncoder.encode(function);

/*
Send the request and wait for the response using eth call since
it's a read only transaction with no cost associated
*/
EthCall response = w3.ethCall(
  Transaction.createEthCallTransaction(credentials.getAddress(), contractAddress, encodedFunction),
  DefaultBlockParameterName.LATEST).send();

balance = Numeric.toBigInt(response.getValue());

String addressTo = "YourFriendsAddress";
BigInteger amount = BigInteger.valueOf(500);

// 使用 wrapper
TransactionReceipt receipt = javaToken.transfer(addressTo,amount).send();

// Without java wrapper

// 定义想要调用的函数
Function function = new Function("transfer", Arrays.asList(new Address(addressTo), new Uint256(amount)),  Collections.emptyList());

// 编码，以便合约可以理解调用哪个函数
String encodedFunction = FunctionEncoder.encode(function);

/*
Need to use a TransactionManager here since transfer actually alters the state of the blockchain and credentials are therefore relevant
*/
TransactionManager transactionManager = new FastRawTransactionManager(w3, credentials);

// Send the transaction off using transactionManager and wait for the hash
String transactionHash = transactionManager.sendTransaction(DefaultGasProvider.GAS_PRICE,
                                                            DefaultGasProvider.GAS_LIMIT, contractAddress, encodedFunction,
                                                            BigInteger.ZERO).getTransactionHash();

// 获取交易收据
Optional<TransactionReceipt> transactionReceipt =
  w3.ethGetTransactionReceipt(transactionHash).send().getTransactionReceipt();
if(transactionReceipt.isEmpty())
  receipt = null;
else
  receipt = transactionReceipt.get();

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