简单使用 Hyperledger-Fabric-Java-SDK

发表于 2020-03-11 更新于 2021-12-15 分类于技术分享

介绍如何用 Fabric Java SDK 进行简单的数据块插入和查询

环境

Hyperledger Fabric 2.0
Fabric Java SDK 2.0.0

示例

public class LocalUser implements User {
    private String name;
    private String mspId;
    private Enrollment enrollment;

    LocalUser(String name, String mspId, String keyFile, String certFile) throws Exception {
        this.name = name;
        this.mspId = mspId;
        this.enrollment = loadFromPemFile(keyFile, certFile);
    }

    private Enrollment loadFromPemFile(String keyFile, String certFile) throws Exception {
        byte[] keyPem = Files.readAllBytes(Paths.get(keyFile));
        byte[] certPem = Files.readAllBytes(Paths.get(certFile));
        CryptoPrimitives suite = new CryptoPrimitives();
        PrivateKey privateKey = suite.bytesToPrivateKey(keyPem);
        return new X509Enrollment(privateKey, new String(certPem));
    }

    @Override
    public String getName() {
        return name;
    }

    public Set<String> getRoles() {
        return null;
    }

    public String getMspId() {
        return mspId;
    }

    @Override
    public Enrollment getEnrollment() {
        return enrollment;
    }

    @Override
    public String getAccount() {
        return null;
    }

    @Override
    public String getAffiliation() {
        return null;
    }

}

public class FabricTest {

    private static final String BASE_PATH = "./fabric";
    private static final String CHANNEL_NAME = "CHANNEL_NAME";
    private static final String CHAINCODE_ID = "CHAINCODE_ID";
    private static final Map<String, String> ORDERER_MAP = new HashMap<>();
    private static final Map<String, String> PEER_MAP = new HashMap<>();
    private static final boolean TLS = true;

    static
        String protocol = "grpc";
        if(TLS) {
            protocol += "s";
        }
        ORDERER_MAP.put("test.com", protocol + "://127.0.0.1:7050");
        PEER_MAP.put("peer.test.com", protocol + "://127.0.0.1:7051");
    }

    public static void main(String[] args) throws Exception {
        String keyFile = BASE_PATH + "***/user-key.pem";
        String certFile = BASE_PATH + "***/user-cert.pem";
        LocalUser user = new LocalUser("username", "mspId", keyFile, certFile);

        HFClient client = HFClient.createNewInstance();
        client.setCryptoSuite(CryptoSuite.Factory.getCryptoSuite());
        client.setUserContext(user);

        Channel channel = client.newChannel(CHANNEL_NAME);
        for (Map.Entry<String, String> entry : ORDERER_MAP.entrySet()) {
            Properties properties = new Properties();
            if(TLS) {
                properties.setProperty("clientCertFile", "对应配置目录下users/***/tls/client.crt文件");
                properties.setProperty("clientKeyFile", "对应配置目录下users/***/tls/client.key文件");
                properties.setProperty("pemFile", "对应配置目录下/tls/server.crt文件");
                properties.setProperty("hostnameOverride", entry.getKey());
                properties.setProperty("sslProvider", "openSSL");
                properties.setProperty("negotiationType", "TLS");
            }
            channel.addOrderer(client.newOrderer(entry.getKey(), entry.getValue(), properties));
        }
        for (Map.Entry<String, String> entry : PEER_MAP.entrySet()) {
            Properties properties = new Properties();
            if(TLS) {
                properties.setProperty("clientCertFile", "对应配置目录下users/***/tls/client.crt文件");
                properties.setProperty("clientKeyFile", "对应配置目录下users/***/tls/client.key文件");
                properties.setProperty("pemFile", "对应配置目录下/tls/server.crt文件");
                properties.setProperty("hostnameOverride", entry.getKey());
                properties.setProperty("sslProvider", "openSSL");
                properties.setProperty("negotiationType", "TLS");
            }
            channel.addPeer(client.newPeer(entry.getKey(), entry.getValue(), properties));
        }
        channel.initialize();

        System.out.format("Valid: %s\n", invokeRequest(client, channel, "insert", "ID1","VALUE222"));
        System.out.format("Message: %s\n", queryRequest(client, channel, "query", "ID1"));
    }

    private static String queryRequest(HFClient client, Channel channel, String function, String... args) throws Exception {
        QueryByChaincodeRequest request = client.newQueryProposalRequest();
        request.setChaincodeName(CHAINCODE_ID);
        request.setFcn(function);
        request.setArgs(args);
        ProposalResponse[] responses = channel.queryByChaincode(request).toArray(new ProposalResponse[0]);
        return responses[0].getProposalResponse().getResponse().getPayload().toStringUtf8();
    }

    private static boolean invokeRequest(HFClient client, Channel channel, String function, String... args) throws Exception {
        TransactionProposalRequest request = client.newTransactionProposalRequest();
        request.setChaincodeName(CHAINCODE_ID);
        request.setFcn(function);
        request.setArgs(args);
        Collection<ProposalResponse> responses = channel.sendTransactionProposal(request);
        BlockEvent.TransactionEvent event = channel.sendTransaction(responses).get();
        return event.isValid();
    }
}

Java模拟JavaScript生成器函数

发表于 2020-01-02 更新于 2021-12-15 分类于技术分享

js中可以定义生成器函数, 使用yield迭代结果, 例如

function* gen() { 
  yield 1;
  yield 2;
  yield 3;
}

let g = gen(); 
g.next();
g.next();

本文中尝试在Java环境中实现类似的效果

实现

Generator.java

生成器类

import java.util.concurrent.Semaphore;

public class Generator {

    private Function function;

    private Runnable runnable;
    private Thread thread;

    private Semaphore readLock;
    private Semaphore writeLock;

    private Result result;
    private Object nextValue;
    private boolean done = true;

    public Generator(Function function) {
        this.function = function;
        this.runnable = () -> {
            try {
                this.writeLock.acquire();
                Object value = this.function.run(this);
                this.result = new Result(value, true);
                this.readLock.release();
            } catch (Exception e) {
                e.printStackTrace();
            }
        };
        this.reset();
    }

    public boolean isDone() {
        return done;
    }

    public synchronized void reset() {
        this.close();
        this.readLock = new Semaphore(0);
        this.writeLock = new Semaphore(0);
        this.result = null;
        this.nextValue = null;
        this.done = false;
        this.thread = new Thread(this.runnable);
        this.thread.start();
    }

    public synchronized void close() {
        if (this.thread != null) {
            this.thread.stop();
            this.thread = null;
        }
    }

    public synchronized Result next() throws InterruptedException {
        return this.next(null);
    }

    public synchronized Result next(Object value) throws InterruptedException {
        if (this.done) {
            return null;
        }
        this.nextValue = value;
        this.writeLock.release();
        this.readLock.acquire();
        Result result = this.result;
        this.done = result.isDone();
        return result;
    }

    public Object yield(Object value) throws InterruptedException {
        this.result = new Result(value, false);
        this.readLock.release();
        this.writeLock.acquire();
        return this.nextValue;
    }

    @FunctionalInterface
    public interface Function {
        Object run(Generator context) throws Exception;
    }

    public static class Result {
        private Object value;
        private boolean done;

        private Result(Object value, boolean done) {
            this.value = value;
            this.done = done;
        }

        public Object getValue() {
            return value;
        }

        public boolean isDone() {
            return done;
        }

        @Override
        public String toString() {
            return "Result{" +
                    "value=" + value +
                    ", done=" + done +
                    '}';
        }
    }
}

测试

Java

public class Main {

    public static void main(String[] args) throws InterruptedException {
        Generator generator = new Generator(context -> {
            int count = 0;
            for (int i = 0; i < 10; i++) {
                Integer value = (Integer) context.yield(i);
                count += value == null ? 0 : value;
            }
            return count;
        });

        Generator.Result result = null;
        do {
            result = generator.next(result == null ? null : result.getValue());
            System.out.println(result);
        } while (!result.isDone());
    }
}

/* 输出结果
Result{value=0, done=false}
Result{value=1, done=false}
Result{value=2, done=false}
Result{value=3, done=false}
Result{value=4, done=false}
Result{value=5, done=false}
Result{value=6, done=false}
Result{value=7, done=false}
Result{value=8, done=false}
Result{value=9, done=false}
Result{value=45, done=true}
*/

对应的JavaScript代码

let generator = (function* Generator() {
    let count = 0;
    for (let i = 0; i < 10; i++) {
        count += (yield i) || 0;
    }
    return count;
})();

let result;
do {
    result = generator.next(result && result.value);
    console.log(result);
} while (!result.done)

/* 输出结果
{value: 0, done: false}
{value: 1, done: false}
{value: 2, done: false}
{value: 3, done: false}
{value: 4, done: false}
{value: 5, done: false}
{value: 6, done: false}
{value: 7, done: false}
{value: 8, done: false}
{value: 9, done: false}
{value: 45, done: true}
*/