Go语言视频零基础入门到精通

admin

使用java开发区块链

  这里需要使用的环境 web3j，nodejs

  安装编译sol工具

1. [code]$ npm install -g solc

复制代码

[/code]

  保存为hello.sol文件到本地

1. [code]pragma solidity 0.4.19;  
2. contract hello {  
3. function main(uint a) constant returns (uint b)   
4.     {  
5.         uint result = a * 8;  
6.         return result;  
7.     }  
8. }  

复制代码

[/code]

  编译sol文件

1. [code]$ solcjs <sol文件目录>   --optimize  --bin --abi --output-dir <输出目录>
3. //demo
4. $ solcjs F:\\hello.sol   --optimize  --bin --abi --output-dir F:\\

复制代码

[/code]

  出现这种错误

1. [code]Failed to write F:\F_\hello_sol_hello.bin: Error: ENOENT: no such file or directory, open "F:\F_\hello_sol_hello.bin"
2. Failed to write F:\F_\hello_sol_hello.abi: Error: ENOENT: no such file or directory, open "F:\F_\hello_sol_hello.abi"

复制代码

[/code]

  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

1. [code]$ 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>
2. //demo
3. $ 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

复制代码

[/code]

  生成成功

1. [code]package xyz.lihang.demo.eth.sol;
3. import java.math.BigInteger;
4. import java.util.Arrays;
5. import org.web3j.abi.TypeReference;
6. import org.web3j.abi.datatypes.Function;
7. import org.web3j.abi.datatypes.Type;
8. import org.web3j.abi.datatypes.generated.Uint256;
9. import org.web3j.crypto.Credentials;
10. import org.web3j.protocol.Web3j;
11. import org.web3j.protocol.core.RemoteCall;
12. import org.web3j.tx.Contract;
13. import org.web3j.tx.TransactionManager;
15. /**
16. * <p>Auto generated code.
17. * <p><strong>Do not modify!</strong>
18. * <p>Please use the <a href="https://docs.web3j.io/command_line.html">web3j command line tools</a>,
19. * or the org.web3j.codegen.SolidityFunctionWrapperGenerator in the
20. * <a href="https://github.com/web3j/web3j/tree/master/codegen">codegen module</a> to update.
21. *
22. * <p>Generated with web3j version 3.2.0.
23. */
24. public class Hello_sol_hello extends Contract {
25.     private static final String BINARY = "60606040523415600e57600080fd5b609a8061001c6000396000f300606060405260043610603e5763ffffffff7c0100000000000000000000000000000000000000000000000000000000600035041663ab3ae25581146043575b600080fd5b3415604d57600080fd5b60566004356068565b60405190815260200160405180910390f35b600802905600a165627a7a723058200cc51f5dad45190b24189d9f8ff836d704bcebc9862cfd669e054b8c8f19f66c0029";
27.     protected Hello_sol_hello(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
28.         super(BINARY, contractAddress, web3j, credentials, gasPrice, gasLimit);
29.     }
31.     protected Hello_sol_hello(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
32.         super(BINARY, contractAddress, web3j, transactionManager, gasPrice, gasLimit);
33.     }
35.     public RemoteCall<BigInteger> main(BigInteger a) {
36.         Function function = new Function("main",
37.                 Arrays.<Type>asList(new org.web3j.abi.datatypes.generated.Uint256(a)),
38.                 Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));
39.         return executeRemoteCallSingleValueReturn(function, BigInteger.class);
40.     }
42.     public static RemoteCall<Hello_sol_hello> deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
43.         return deployRemoteCall(Hello_sol_hello.class, web3j, credentials, gasPrice, gasLimit, BINARY, "");
44.     }
46.     public static RemoteCall<Hello_sol_hello> deploy(Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
47.         return deployRemoteCall(Hello_sol_hello.class, web3j, transactionManager, gasPrice, gasLimit, BINARY, "");
48.     }
50.     public static Hello_sol_hello load(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
51.         return new Hello_sol_hello(contractAddress, web3j, credentials, gasPrice, gasLimit);
52.     }
54.     public static Hello_sol_hello load(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
55.         return new Hello_sol_hello(contractAddress, web3j, transactionManager, gasPrice, gasLimit);
56.     }
57. }

复制代码

[/code]

  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