Hyperledger區塊數據的訪問

簡介

本文介紹了訪問Hyperledger區塊數據的幾種方法.

REST API

Hyperledger提供了多個REST API (https://hyperledger-fabric.readthedocs.io/en/latest/API/CoreAPI/#rest-api) 用於訪問Hyperledger區塊數據.

示例1： 獲取區塊鏈長度

請求

http://192.168.99.100:7050/chain/

響應

{
    "height": 5,
    "currentBlockHash": "9UIs99F9Qq0RvwOzCEDG0SHvBrdoOHy0rexOICJ56aiIQbnszEO9y2QpjbMnrzIp3ehGh6W8FWY8eqbBFqaOVA==",
    "previousBlockHash": "AABHooEnVMuv4JO4roHqgcNAOf3mcUqOV6sTrCWeuPcKf/ji4tYXJ5cONgcQTwoIowf1wAqhZObFmjkT1QLmsQ=="
}

示例2： 獲取區塊數據

請求

http://192.168.99.100:7050/chain/blocks/4

響應

{
    "transactions": [
        {
            "type": 2,
            "chaincodeID": "EgRteWNj",
            "payload": "CigIARIGEgRteWNjGhwKBmludm9rZQoHdGVzdEtleQoJdGVzdFZhbHVl",
            "txid": "4a05fbd2-f17d-46eb-abec-a6218b404117",
            "timestamp": {
                "seconds": 1476704491,
                "nanos": 740300402
            },
            "nonce": "jYFNo67ks3JhWh3PwxCJG0qK0rnBojwe",
            "cert": "MIICQTCCAeegAwIBAgIQMQ6RNvEkQKqWqqMx6vVJujAKBggqhkjOPQQDAzAxMQswCQYDVQQGEwJVUzEUMBIGA1UEChMLSHlwZXJsZWRnZXIxDDAKBgNVBAMTA3RjYTAeFw0xNjEwMDUxMTE5MjdaFw0xNzAxMDMxMTE5MjdaMEUxCzAJBgNVBAYTAlVTMRQwEgYDVQQKEwtIeXBlcmxlZGdlcjEgMB4GA1UEAxMXVHJhbnNhY3Rpb24gQ2VydGlmaWNhdGUwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAASzqDkDtyveHNTcz0tD73PV5xvXFU0JpDxVvN8LEAAKtnP+TfkPT42EmERcSP+oOlzpfjBD8iGaOq4wQGbPckWKo4HMMIHJMA4GA1UdDwEB/wQEAwIHgDAMBgNVHRMBAf8EAjAAMA0GA1UdDgQGBAQBAgMEMA8GA1UdIwQIMAaABAECAwQwTQYGKgMEBQYHAQH/BECqjFoEQcSb6N1SGRE8uc03WMz4ccjSFfplLUrSXxdUUA81LciUswvKeDz8m3abk8z/pVc06nNFAcRWXkHfqzEJMDoGBioDBAUGCAQwN90tistCDXKOkUCQUjzKbZsrEy2A/iOgGtiHru7yVoIawPIeHfnfdfP+LEtCgMrkMAoGCCqGSM49BAMDA0gAMEUCIQC5ClRb0pPCdL+peOq/Cc6Z+Wy+KTq0mIB6FAEvy5gMcwIgFI1HWhlGGGjeqLTrLvcIeWamck2ISYImcIBZIfE+xlI=",
            "signature": "MEUCIHRnWCQmt+4QoiY01aiDU+0567xUgaiEZ6zZr+gDg8D2AiEA+OgCGGxWbQTkmC0IB4nJoiU65Dv/pR27XDirhtXgStU="
        }
    ],
    "stateHash": "cxUZAjaQar85ZGvgt4z3soRMpQjJpDrpLBkFbwqQSVb1rebXcMT1kMzNA45MX9ybB/sILXCslN1C9yprmhAVng==",
    "previousBlockHash": "9UIs99F9Qq0RvwOzCEDG0SHvBrdoOHy0rexOICJ56aiIQbnszEO9y2QpjbMnrzIp3ehGh6W8FWY8eqbBFqaOVA==",
    "nonHashData": {
        "localLedgerCommitTimestamp": {
            "seconds": 1476704492,
            "nanos": 779081508
        },
        "chaincodeEvents": [
            {}
        ]
    }
}

Java Client API

Hyperledger Java Client API (https://github.com/hyperledger/fabric-api)提供較為底層的接口來訪問Hyperledger區塊數據. 以下示例代碼顯示如何解析Invocation類的區塊中的payload.

privatevoiddecodeChaincodeInvocationSpec() {
    try {
        String base64String = "CigIARIGEgRteWNjGhwKBmludm9rZQoHdGVzdEtleQoJdGVzdFZhbHVl";
        byte[] decoded = javax.xml.bind.DatatypeConverter.parseBase64Binary(base64String);

        Chaincode.ChaincodeInvocationSpec invocationSpec =
                Chaincode.ChaincodeInvocationSpec.parseFrom(decoded);

        Map<Descriptors.FieldDescriptor, Object> fields = invocationSpec.getAllFields();
        for (Descriptors.FieldDescriptor key : fields.keySet()) {
            Chaincode.ChaincodeSpec value = (Chaincode.ChaincodeSpec) fields.get(key);
            System.out.println("key:" + key);
            System.out.println("value:" + value);
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

相應的輸出為：

key:protos.ChaincodeInvocationSpec.chaincodeSpec
value:type: GOLANG
chaincodeID {
  name: "mycc"
}
ctorMsg {
  args: "invoke"
  args: "testKey"
  args: "testValue"
}

總結

本文介紹了使用Hyperledger REST和Java Client API訪問Hyperledger區塊數據的方法.