fabric java sdk spring boot项目详解

Fabric Java SDK 是为 Hyperledger Fabric 区块链平台开发的 Java SDK，它提供了访问 Fabric 网络的所有必要接口，包括身份验证、链码调用、交易提交等。Spring Boot 是一个基于 Spring 框架的快速开发应用程序的工具，它提供了诸多便利的特性，如自动配置、快速开发等。

在使用 Fabric Java SDK 开发 Spring Boot 项目时，我们可以采用以下步骤：

1. 配置 Maven 依赖

在 pom.xml 文件中添加以下依赖：

<dependency>
    <groupId>org.hyperledger.fabric-sdk-java</groupId>
    <artifactId>fabric-sdk-java</artifactId>
    <version>2.2.0</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

2. 配置 Fabric SDK

在 Spring Boot 项目中，我们可以使用 @Configuration 注解配置 Fabric SDK。在配置中，我们需要指定以下参数：

- Fabric 网络的 CA 证书
- Fabric 网络的 MSP 证书
- Fabric 网络的连接配置文件

@Configuration
public class FabricConfig {
    private static final String CONNECTION_PROFILE_PATH = "connection-profile.yaml";
    private static final String MSP_PATH = "/msp";
    private static final String CA_ORG1_URL = "http://localhost:7054";
    private static final String CHANNEL_NAME = "mychannel";

    @Bean
    public NetworkConfig getNetworkConfig() throws Exception {
        Path connectionProfilePath = Paths.get(CONNECTION_PROFILE_PATH);
        return NetworkConfig.fromYamlFile(connectionProfilePath.toFile());
    }

    @Bean
    public User getUser(NetworkConfig networkConfig) throws Exception {
        UserContext userContext = new UserContext();
        userContext.setName("user1");
        userContext.setAffiliation("org1");
        userContext.setMspId("Org1MSP");
        Path mspPath = Paths.get(networkConfig.getOrganizationInfo("Org1").getMspId(), MSP_PATH);
        userContext.setEnrollment(new Enrollment() {
            @Override
            public PrivateKey getKey() {
                try {
                    return loadPrivateKey(mspPath);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }

            @Override
            public String getCert() {
                try {
                    return new String(loadCert(mspPath), "UTF-8");
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }
        });
        return userContext;
    }

    @Bean
    public FabricGateway getGateway(NetworkConfig networkConfig, User user) throws Exception {
        Gateway.Builder builder = Gateway.createBuilder();
        builder.identity(user);
        builder.networkConfig(networkConfig);
        return builder.connect().get();
    }

    @Bean
    public Contract getContract(FabricGateway gateway) throws Exception {
        return gateway.getNetwork(CHANNEL_NAME).getContract("mychaincode");
    }

    private byte[] loadCert(Path mspPath) throws Exception {
        Path certPath = mspPath.resolve(Paths.get("signcerts", "cert.pem"));
        return Files.readAllBytes(certPath);
    }

    private PrivateKey loadPrivateKey(Path mspPath) throws Exception {
        Path keyPath = mspPath.resolve(Paths.get("keystore", "priv.key"));
        byte[] keyBytes = Files.readAllBytes(keyPath);
        return getPrivateKeyFromBytes(keyBytes);
    }

    private PrivateKey getPrivateKeyFromBytes(byte[] keyBytes) throws Exception {
        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory factory = KeyFactory.getInstance("EC");
        return factory.generatePrivate(spec);
    }
}

3. 实现接口方法

在接口方法中，我们可以使用 Fabric SDK 提供的 API 实现对链码的调用、交易的提交等操作。

@RestController
public class MyController {
    private static final String CHAINCODE_NAME = "mychaincode";
    private static final String FUNCTION_NAME = "invoke";
    private static final String KEY = "key1";
    private static final String VALUE = "value1";

    @Autowired
    private Contract contract;

    @PostMapping("/set")
    public String setValue() throws Exception {
        contract.submitTransaction(FUNCTION_NAME, KEY, VALUE);
        return "success";
    }

    @GetMapping("/get")
    public String getValue() throws Exception {
        byte[] result = contract.evaluateTransaction(FUNCTION_NAME, KEY);
        return new String(result, "UTF-8");
    }
}

以上就是使用 Fabric Java SDK 开发 Spring Boot 项目的流程。通过这种方式，我们可以方便地实现对 Fabric 网络的访问，并快速开发出符合需求的应用程序。