使用web3j工具生成java版本的智能合约

这里需要使用的环境 web3j，nodejs

  • 安装编译sol工具

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$ npm install -g solc
  • 保存为hello.sol文件到本地

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pragma solidity 0.4.19; 

contract hello { 

function main(uint a) constant returns (uint b)  

    { 

        uint result = a * 8; 

        return result; 

    } 

}
  • 编译sol文件

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$ solcjs <sol文件目录>   --optimize  --bin --abi --output-dir <输出目录>

 

//demo

$ solcjs F:\\hello.sol   --optimize  --bin --abi --output-dir F:\\

出现这种错误

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Failed to write F:\F_\hello_sol_hello.bin: Error: ENOENT: no such file or directory, open 'F:\F_\hello_sol_hello.bin'

Failed to write F:\F_\hello_sol_hello.abi: Error: ENOENT: no such file or directory, open 'F:\F_\hello_sol_hello.abi'

这里有个坑，就是使用solcjs 编译智能合约文件输出到目录会有一个文件夹，这个需要手动创建，我这里输出目录到F:\\ 但是它还是要输出到F:\\F_\ 下，这里的F_文件夹需要我们创建！

  • 编译成功,记录下bin 和 abi后缀的文件
  • 使用web3j工具生成java版本的智能合约
  • web3j 命令行工具下载

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$ web3j solidity generate <编译的bin文件地址> <编译的abi文件地址> -o <输出目录> -p <java包名>

//demo

$ web3j solidity generate F:\F_\hello_sol_hello.bin F:\F_\hello_sol_hello.abi -o E:\etheth\src\main\java -p xyz.lihang.demo.eth.sol

　PS：使用web3j命令，需要进入https://github.com/web3j/web3j/releases/tag/v3.3.1网站，下载web3j-3.3.1.tar，并解压。

　　　进入目录bin下，在此目录命令行执行web3j，否则web3j bash命令不存在

  • 生成成功

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package xyz.lihang.demo.eth.sol;

 

import java.math.BigInteger;

import java.util.Arrays;

import org.web3j.abi.TypeReference;

import org.web3j.abi.datatypes.Function;

import org.web3j.abi.datatypes.Type;

import org.web3j.abi.datatypes.generated.Uint256;

import org.web3j.crypto.Credentials;

import org.web3j.protocol.Web3j;

import org.web3j.protocol.core.RemoteCall;

import org.web3j.tx.Contract;

import org.web3j.tx.TransactionManager;

 

/**

 * <p>Auto generated code.

 * <p><strong>Do not modify!</strong>

 * <p>Please use the <a href="https://docs.web3j.io/command_line.html">web3j command line tools</a>,

 * or the org.web3j.codegen.SolidityFunctionWrapperGenerator in the

 * <a href="https://github.com/web3j/web3j/tree/master/codegen">codegen module</a> to update.

 *

 * <p>Generated with web3j version 3.2.0.

 */

public class Hello_sol_hello extends Contract {

    private static final String BINARY = "60606040523415600e57600080fd5b609a8061001c6000396000f300606060405260043610603e5763ffffffff7c0100000000000000000000000000000000000000000000000000000000600035041663ab3ae25581146043575b600080fd5b3415604d57600080fd5b60566004356068565b60405190815260200160405180910390f35b600802905600a165627a7a723058200cc51f5dad45190b24189d9f8ff836d704bcebc9862cfd669e054b8c8f19f66c0029";

 

    protected Hello_sol_hello(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {

        super(BINARY, contractAddress, web3j, credentials, gasPrice, gasLimit);

    }

 

    protected Hello_sol_hello(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {

        super(BINARY, contractAddress, web3j, transactionManager, gasPrice, gasLimit);

    }

 

    public RemoteCall<BigInteger> main(BigInteger a) {

        Function function = new Function("main",

                Arrays.<Type>asList(new org.web3j.abi.datatypes.generated.Uint256(a)),

                Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));

        return executeRemoteCallSingleValueReturn(function, BigInteger.class);

    }

 

    public static RemoteCall<Hello_sol_hello> deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {

        return deployRemoteCall(Hello_sol_hello.class, web3j, credentials, gasPrice, gasLimit, BINARY, "");

    }

 

    public static RemoteCall<Hello_sol_hello> deploy(Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {

        return deployRemoteCall(Hello_sol_hello.class, web3j, transactionManager, gasPrice, gasLimit, BINARY, "");

    }

 

    public static Hello_sol_hello load(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {

        return new Hello_sol_hello(contractAddress, web3j, credentials, gasPrice, gasLimit);

    }

 

    public static Hello_sol_hello load(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {

        return new Hello_sol_hello(contractAddress, web3j, transactionManager, gasPrice, gasLimit);

    }

}

一定要注意合约调用后进行挖矿，这样才能网络确认，才能使用合约

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