在上一篇文章中 《Hyperledger Fabric 2.x 自定义智能合约》 分享了智能合约的安装并使用 cli 客户端进行合约的调用；本文将使用 Java 代码基于 fabric-gateway-java 进行区块链网络的访问与交易，并集成 SpringBoot 框架。
Fabric Gateway SDK 实现Fabric的编程模型，提供了一系列简单的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，每个网关都了解网络信道拓扑，包括组织的多个Peer节点和排序节点，使应用程序专注于业务逻辑；Peer节点可以使用gossip协议在组织内部和组织之间相互通信。
二、Mavn依赖
添加网关sdk的依赖：
<dependency>
<groupId>org.hyperledger.fabricgroupId>
<artifactId>fabric-gateway-javaartifactId>
<version>2.2.3version>
dependency>
三、准备配置文件
工程的目录结构如下图所示：
3.1. 准备网络证书
创建目录 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. 创建网络配置
创建文件 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"
}
]
}
}
}
需按实际情况修改url中的地址，内容中分别包含了
channels、organizations、orderers、peers、ca的配置
3.3. SpringBoot配置
在 application.yml 中添加以下内容，用于访问网关的相关配置：
fabric:
# wallet文件夹路径(自动创建)
walletDirectory: wallet
# 网络配置文件路径
networkConfigPath: connection.json
# 用户证书路径
certificatePath: crypto-config/peerOrganizations/org1.example.com/users/User1@org1.example.com/msp/signcerts/User1@org1.example.com-cert.pem
# 用户私钥路径
privateKeyPath: crypto-config/peerOrganizations/org1.example.com/users/User1@org1.example.com/msp/keystore/priv_sk
# 访问的组织名
mspid: Org1MSP
# 用户名
username: user1
# 通道名字
channelName: mychannel
# 链码名字
contractName: mycc
四、连接合约
分别构建网关、通道和合约的Bean对象，代码如下：
/**
* 连接网关
*/
@Bean
public Gateway connectGateway() throws IOException, InvalidKeyException, CertificateException {
//使用org1中的user1初始化一个网关wallet账户用于连接网络
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));
//根据connection.json 获取Fabric网络连接对象
Gateway.Builder builder = Gateway.createBuilder()
.identity(wallet, username)
.networkConfig(Paths.get(this.networkConfigPath));
//连接网关
return builder.connect();
}
/**
* 获取通道
*/
@Bean
public Network network(Gateway gateway) {
return gateway.getNetwork(this.channelName);
}
/**
* 获取合约
*/
@Bean
public Contract contract(Network network) {
return network.getContract(this.contractName);
}
五、合约调用
创建controller类，注入Contract对象调用合约方法：
@Resource
private Contract contract;
@Resource
private 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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