web3j 部署合约
环境:mac os & android studio
官网:here
以太坊 web3j for java 配置和使用<1>: here
以太坊 web3j for java 使用 - 为用户创建凭证credentials <2>:here
零、书写合约
本文还是使用MetaCoin.sol
pragma solidity ^0.4.2;contract MetaCoin {mapping (address => uint) balances;event Transfer(address indexed _from, address indexed _to, uint256 _value);function MetaCoin() {balances[tx.origin] = 10000;}function sendCoin(address receiver, uint amount) returns(bool sufficient) {if (balances[msg.sender] < amount) return false;balances[msg.sender] -= amount;balances[receiver] += amount;Transfer(msg.sender, receiver, amount);return true;}function getBalance(address addr) returns(uint) {return balances[addr];}}
一、编译合约
solc <contract>.sol --bin --abi --optimize -o <output-dir>/
====>生产 .abi 和 .bin 文件
例如,在MetaCoin.sol文件目录下输入:solc MetaCoin.sol --bin --abi --optimize -o /Users/pro/Desktop
二、生成 .java文件
web3j solidity generate [--javaTypes|--solidityTypes] /path/to/<smart-contract>.bin /path/to/<smart-contract>.abi -o /path/to/src/main/java -p anisation.name
例如:
然后将生成的 .java文件导入到安卓项目中。
三、部署合约
YourSmartContract contract = YourSmartContract.deploy(<web3j>, <credentials>, GAS_PRICE, GAS_LIMIT,[<initialValue>,]<param1>, ..., <paramN>).send();
例如:
MetaCoin contract = MetaCoin.deploy(web3, credentials, GAS_PRICE, GAS_LIMIT).send();System.out.println(contract.getContractAddress());
或者可以加载已经部署在私有链上面的合约:
YourSmartContract contract = YourSmartContract.load("0x<address>|<ensName>", web3j, credentials, GAS_PRICE, GAS_LIMIT);
例如:
AllBikeShared contract = AllBikeShared.load("0x055a864a5f39f9eecd17e729e2cfc4fb6b12c19b", web3, credentials, GAS_PRICE, GAS_LIMIT);
四、调用合约
1.call 的方式,不改变智能合约的状态
Type result = contract.someMethod(<param1>, ...).send();
例如:
BigInteger result = contract.getUserCount().send();