编写一个应用程序来连接到 fabrc 网络中，通过调用智能合约来访问账本.
fabric gateway
fabric gateway 有两个项目，一个是 fabric-gateway-java , 一个是 fabric-gateway。
fabric-gateway-java 是比较早的项目，使用起来较为麻烦需要提供一个 connection.json 配置文件，该配置文件中要详细配置网络中的各个节点的信息。
fabric-gateway 使用起来较为简单，不在需要 connection.json 配置文件，只需要指定网络中的一个节点连接就可以了。
fabric 官方建议如果是 fabrc 2.4 或者之后的版本建议使用 fabric-gateway。
本篇内容基于
fabric-gateway讲解，fabric 版本 v2.4.1
使用 fabric-gateway
Fabric Gateway 是 Hyperledger Fabric 区块链网络的核心组件，代表客户端应用程序协调提交事务和查询分类账状态所需的操作。通过使用 Gateway，客户端应用程序只需要连接到 Fabric 网络中的单个端点。
官方示例： https://github.com/hyperledger/fabric-samples/tree/main/asset-transfer-events https://github.com/hyperledger/fabric-samples/tree/main/asset-transfer-basic
fabric-gateway 依赖
<dependency>
<groupId>org.hyperledger.fabric</groupId>
<artifactId>fabric-gateway</artifactId>
<version>1.0.1</version>
</dependency>
连接 fabric 网络
application.properties 配置文件：
# 应用名称
spring.application.name=hyperledger-fabric-app-java-demo
# 应用服务 WEB 访问端口
server.port=8080
fabric.networkConnectionConfigPath=src/main/resources/org1ProdNetworkConnection.json
fabric.mspId=Org1MSP
fabric.certificatePath=src/main/resources/crypto-config/prod-network/peerOrganizations/org1.example.com/users/User1@org1.example.com/msp/signcerts/User1@org1.example.com-cert.pem
fabric.privateKeyPath=src/main/resources/crypto-config/prod-network/peerOrganizations/org1.example.com/users/User1@org1.example.com/msp/keystore/priv_sk
fabric.tlsCertPath=src/main/resources/crypto-config/prod-network/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt
fabric.channel=businesschannel
logging.level.org.hyperledger=trace
src/main/resources/crypto-config/prod-network 路径下存放的是身份信息文件.
初始化 Gateway , Network , Contract 对象
import io.grpc.ManagedChannel;
import io.grpc.netty.shaded.io.grpc.netty.GrpcSslContexts;
import io.grpc.netty.shaded.io.grpc.netty.NettyChannelBuilder;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.hyperledger.fabric.client.CallOption;
import org.hyperledger.fabric.client.Contract;
import org.hyperledger.fabric.client.Gateway;
import org.hyperledger.fabric.client.Network;
import org.hyperledger.fabric.client.identity.Identities;
import org.hyperledger.fabric.client.identity.Signers;
import org.hyperledger.fabric.client.identity.X509Identity;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.PrivateKey;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.concurrent.TimeUnit;
/**
* author he peng
* date 2022/1/22 21:21
*/
@Configuration
@AllArgsConstructor
@Slf4j
public class HyperLedgerFabricGatewayConfig {
final HyperLedgerFabricProperties hyperLedgerFabricProperties;
@Bean
public Gateway gateway() throws Exception {
BufferedReader certificateReader = Files.newBufferedReader(Paths.get(hyperLedgerFabricProperties.getCertificatePath()), StandardCharsets.UTF_8);
X509Certificate certificate = Identities.readX509Certificate(certificateReader);
BufferedReader privateKeyReader = Files.newBufferedReader(Paths.get(hyperLedgerFabricProperties.getPrivateKeyPath()), StandardCharsets.UTF_8);
PrivateKey privateKey = Identities.readPrivateKey(privateKeyReader);
Gateway gateway = Gateway.newInstance()
.identity(new X509Identity(hyperLedgerFabricProperties.getMspId() , certificate))
.signer(Signers.newPrivateKeySigner(privateKey))
.connection(newGrpcConnection())
.evaluateOptions(CallOption.deadlineAfter(5, TimeUnit.SECONDS))
.endorseOptions(CallOption.deadlineAfter(15, TimeUnit.SECONDS))
.submitOptions(CallOption.deadlineAfter(5, TimeUnit.SECONDS))
.commitStatusOptions(CallOption.deadlineAfter(1, TimeUnit.MINUTES))
.connect();
log.info("=========================================== connected fabric gateway {} " , gateway);
return gateway;
}
private ManagedChannel newGrpcConnection() throws IOException, CertificateException {
Reader tlsCertReader = Files.newBufferedReader(Paths.get(hyperLedgerFabricProperties.getTlsCertPath()));
X509Certificate tlsCert = Identities.readX509Certificate(tlsCertReader);
return NettyChannelBuilder.forTarget("peer0.org1.example.com:7051")
.sslContext(GrpcSslContexts.forClient().trustManager(tlsCert).build())
.overrideAuthority("peer0.org1.example.com")
.build();
}
@Bean
public Network network(Gateway gateway) {
return gateway.getNetwork(hyperLedgerFabricProperties.getChannel());
}
@Bean
public Contract catContract(Network network) {
return network.getContract("hyperledger-fabric-contract-java-demo" , "CatContract");
}
@Bean
public ChaincodeEventListener chaincodeEventListener(Network network) {
return new ChaincodeEventListener(network);
}
}
链码事件监听
用来监听交易完成之后通知的事件，事件中可以携带数据。
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.hyperledger.fabric.client.ChaincodeEvent;
import org.hyperledger.fabric.client.CloseableIterator;
import org.hyperledger.fabric.client.Network;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
/**
* @author he peng
* @date 2022/3/4
*/
@Slf4j
public class ChaincodeEventListener implements Runnable {
final Network network;
public ChaincodeEventListener(Network network) {
this.network = network;
ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1, new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread thread = new Thread(r);
thread.setDaemon(true);
thread.setName(this.getClass() + "chaincode_event_listener");
return thread;
}
});
executor.execute(this);
}
@Override
public void run() {
CloseableIterator<ChaincodeEvent> events = network.getChaincodeEvents("hyperledger-fabric-contract-java-demo");
log.info("chaincodeEvents {} " , events);
while (events.hasNext()) {
ChaincodeEvent event = events.next();
log.info("receive chaincode event {} , block number {} , payload {} "
, event.getEventName() , event.getBlockNumber() , JSONArray.toJSONString(Base64.decodeBase64(event.getPayload())));
}
}
}
异步调用合约
@PutMapping("/async")
public Map<String, Object> createCatAsync(@RequestBody CatDTO cat) throws Exception {
Map<String, Object> result = Maps.newConcurrentMap();
contract.newProposal("createCat")
.addArguments(cat.getKey(), cat.getName(), String.valueOf(cat.getAge()), cat.getColor(), cat.getBreed())
.build()
.endorse()
.submitAsync();
result.put("status", "ok");
return result;
}
完整示例代码项目:DevX/hyperledger-fabric-app-java-demo
