一、阐明
在上一篇文章中 《Hyperledger Fabric 2.x 自定义智能合约》 分享了智能合约的装置并应用 cli 客户端进行合约的调用；本文将应用 Java 代码基于 fabric-gateway-java 进行区块链网络的拜访与交易，并集成 SpringBoot 框架。
Fabric Gateway SDK 实现Fabric的编程模型，提供了一系列简略的API给应用程序与Fabric区块链网络进行交互；
网络拓扑图：
应用程序将各自的网络交互委托给其网关，每个网关都理解网络信道拓扑，包含组织的多个Peer节点和排序节点，使应用程序专一于业务逻辑；Peer节点能够应用gossip协定在组织外部和组织之间互相通信。
二、Mavn依赖
增加网关sdk的依赖：
<dependency> <groupId>org.hyperledger.fabric</groupId> <artifactId>fabric-gateway-java</artifactId> <version>2.2.3</version></dependency>
三、筹备配置文件
工程的目录构造如下图所示：
3.1. 筹备网络证书
创立目录 crypto-config 把 orderer 和 peer 节点的证书文件复制进来。
证书文件从 fabric-samples 的 test-network 目录中复制 ordererOrganizations 与 peerOrganizations 文件夹：
3.2. 创立网络配置
创立文件 connection.json 内容如下：
{ "name": "basic-network", "version": "1.0.0", "client": { "organization": "Org1", "connection": { "timeout": { "peer": { "endorser": "300" }, "orderer": "300" } } }, "channels": { "mychannel": { "orderers": [ "orderer.example.com" ], "peers": { "peer0.org1.example.com": { "endorsingPeer": true, "chaincodeQuery": true, "ledgerQuery": true, "eventSource": true }, "peer0.org2.example.com": { "endorsingPeer": true, "chaincodeQuery": true, "ledgerQuery": true, "eventSource": true } } } }, "organizations": { "Org1": { "mspid": "Org1MSP", "peers": [ "peer0.org1.example.com" ], "certificateAuthorities": [ "ca-org1" ], "adminPrivateKeyPEM": { "path": "src/main/resources/crypto-config/peerOrganizations/org1.example.com/users/Admin@org1.example.com/msp/keystore/priv_sk" }, "signedCertPEM": { "path": "src/main/resources/crypto-config/peerOrganizations/org1.example.com/users/Admin@org1.example.com/msp/signcerts/Admin@org1.example.com-cert.pem" } }, "Org2": { "mspid": "Org2MSP", "peers": [ "peer0.org2.example.com" ], "certificateAuthorities": [ "ca-org2" ], "adminPrivateKeyPEM": { "path": "src/main/resources/crypto-config/peerOrganizations/org2.example.com/users/Admin@org2.example.com/msp/keystore/priv_sk" }, "signedCertPEM": { "path": "src/main/resources/crypto-config/peerOrganizations/org2.example.com/users/Admin@org2.example.com/msp/signcerts/Admin@org2.example.com-cert.pem" } } }, "orderers": { "orderer.example.com": { "url": "grpcs://192.168.28.134:7050", "mspid": "OrdererMSP", "grpcOptions": { "ssl-target-name-override": "orderer.example.com", "hostnameOverride": "orderer.example.com" }, "tlsCACerts": { "path": "src/main/resources/crypto-config/ordererOrganizations/example.com/orderers/orderer.example.com/tls/ca.crt" }, "adminPrivateKeyPEM": { "path": "src/main/resources/crypto-config/ordererOrganizations/example.com/users/Admin@example.com/msp/keystore/priv_sk" }, "signedCertPEM": { "path": "src/main/resources/crypto-config/ordererOrganizations/example.com/users/Admin@example.com/msp/signcerts/Admin@example.com-cert.pem" } } }, "peers": { "peer0.org1.example.com": { "url": "grpcs://192.168.28.134:7051", "grpcOptions": { "ssl-target-name-override": "peer0.org1.example.com", "hostnameOverride": "peer0.org1.example.com", "request-timeout": 120001 }, "tlsCACerts": { "path": "src/main/resources/crypto-config/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt" } }, "peer0.org2.example.com": { "url": "grpcs://192.168.28.134:9051", "grpcOptions": { "ssl-target-name-override": "peer0.org2.example.com", "hostnameOverride": "peer0.org2.example.com", "request-timeout": 120001 }, "tlsCACerts": { "path": "src/main/resources/crypto-config/peerOrganizations/org2.example.com/peers/peer0.org2.example.com/tls/ca.crt" } } }, "certificateAuthorities": { "ca-org1": { "url": "https://192.168.28.134:7054", "grpcOptions": { "verify": true }, "tlsCACerts": { "path": "src/main/resources/crypto-config/peerOrganizations/org1.example.com/ca/ca.org1.example.com-cert.pem" }, "registrar": [ { "enrollId": "admin", "enrollSecret": "adminpw" } ] }, "ca-org2": { "url": "https://192.168.28.134:8054", "grpcOptions": { "verify": true }, "tlsCACerts": { "path": "src/main/resources/crypto-config/peerOrganizations/org2.example.com/ca/ca.org2.example.com-cert.pem" }, "registrar": [ { "enrollId": "admin", "enrollSecret": "adminpw" } ] } }}需按理论状况批改url中的地址，内容中别离蕴含了channels、organizations、orderers、peers、ca的配置
3.3. SpringBoot配置
在 application.yml 中增加以下内容，用于拜访网关的相干配置：
fabric: # wallet文件夹门路(主动创立) walletDirectory: wallet # 网络配置文件门路 networkConfigPath: connection.json # 用户证书门路 certificatePath: crypto-config/peerOrganizations/org1.example.com/users/User1@org1.example.com/msp/signcerts/User1@org1.example.com-cert.pem # 用户私钥门路 privateKeyPath: crypto-config/peerOrganizations/org1.example.com/users/User1@org1.example.com/msp/keystore/priv_sk # 拜访的组织名 mspid: Org1MSP # 用户名 username: user1 # 通道名字 channelName: mychannel # 链码名字 contractName: mycc
四、连贯合约
别离构建网关、通道和合约的Bean对象，代码如下：
/** * 连贯网关 */@Beanpublic Gateway connectGateway() throws IOException, InvalidKeyException, CertificateException { //应用org1中的user1初始化一个网关wallet账户用于连贯网络 Wallet wallet = Wallets.newFileSystemWallet(Paths.get(this.walletDirectory)); X509Certificate certificate = readX509Certificate(Paths.get(this.certificatePath)); PrivateKey privateKey = getPrivateKey(Paths.get(this.privateKeyPath)); wallet.put(username, Identities.newX509Identity(this.mspid, certificate, privateKey)); //依据connection.json 获取Fabric网络连接对象 Gateway.Builder builder = Gateway.createBuilder() .identity(wallet, username) .networkConfig(Paths.get(this.networkConfigPath)); //连贯网关 return builder.connect();}/** * 获取通道 */@Beanpublic Network network(Gateway gateway) { return gateway.getNetwork(this.channelName);}/** * 获取合约 */@Beanpublic Contract contract(Network network) { return network.getContract(this.contractName);}
五、合约调用
创立controller类，注入Contract对象调用合约办法：
@Resourceprivate Contract contract;@Resourceprivate Network network;@GetMapping("/getUser")public String getUser(String userId) throws ContractException { byte[] queryAResultBefore = contract.evaluateTransaction("getUser",userId); return new String(queryAResultBefore, StandardCharsets.UTF_8);}@GetMapping("/addUser")public String addUser(String userId, String userName, String money) throws ContractException, InterruptedException, TimeoutException { byte[] invokeResult = contract.createTransaction("addUser") .setEndorsingPeers(network.getChannel().getPeers(EnumSet.of(Peer.PeerRole.ENDORSING_PEER))) .submit(userId, userName, money); String txId = new String(invokeResult, StandardCharsets.UTF_8); return txId;}
六、测试接口
调用接口 getUser：
http://127.0.0.1:9001/getUser?userId=1返回：
{ "money": 300, "name": "zlt", "userId": "1"}
调用接口 addUser：
http://127.0.0.1:9001/addUser?userId=6&userName=test6&money=600返回：
2ae291bb6a366b5ba01ad49e4237da8def9e9828cc2c982e8c49d4b763af0157
七、代码下载
gitee：https://gitee.com/zlt2000/my-fabric-application-java
github：https://github.com/zlt2000/my-fabric-application-java
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