Java开发组件

Java版本Chain Connector使用说明

Git库地址：https://github.com/taiyi-io/chain-connector-java

用于访问和操作链平台的Java语言SDK，基于openJDK 18编译。

项目

项目基于apache maven管理

编译

$mvn compile

构建库

$mvn package

运行测试用例

$mvn test

使用范例

连接链平台

首先使用平台分配的私钥数据构建Connector，然后连接链平台的gateway模块。

AccessKey accessKey = gson.fromJson(fileContent, AccessKey.class);
ChainConnector connector = ChainConnector.NewConnectorFromAccess(accessKey);
connector.connect(gatewayHost, gatewayPort);

构建与管理数字资产

首先为数字资产定义数据范式（Schema），然后就能够基于该Schema添加、修改、删除和查询数字资产(Document)。所有变更痕迹自动使用区块链技术持久化存储，并且能够通过getSchemaLog和getDocumentLog接口查询。

//create new schema
String schemaName = "sample";
List<DocumentProperty> properties = new ArrayList<>();
properties.add(new DocumentProperty("name", PropertyType.String));
properties.add(new DocumentProperty("age", PropertyType.Integer));
properties.add(new DocumentProperty("available", PropertyType.Boolean));
conn.createSchema(schemaName, properties);
DocumentSchema schema = conn.getSchema(schemaName);

//add a document
String content = "{\"name\": \"hello\", \"age\": 20, \"available\": true}";
String docID = conn.addDocument(schemaName, "", content);

//check a document
if (conn.hasDocument(schemaName, docID)){
	//update a existed document
    String updatedContent = "{\"name\": \"alice\", \"age\": 18, \"available\": false}";
    conn.updateDocument(schemaName, docID, updatedContent);
}

//get change trace of a document
LogRecords logs = conn.getDocumentLogs(schemaName, docID);

//query documents
QueryCondition condition = new QueryBuilder()
    .AscendBy("name")
    .MaxRecord(20)
    .SetOffset(0)
    .Build();
DocumentRecords records = conn.queryDocuments(schemaName, condition);


//remove document
conn.removeDocument(schemaName, docID);

部署和调用智能合约

部署智能合约时，需要设定合约名称和执行步骤。调用时，指定合约名称和调用参数就可以启动执行。系统允许打开追踪开关，查看合约执行计划和实际运行情况。

String contractName = "contract_create";
List<ContractStep> steps = new ArrayList<>();
steps.add(new ContractStep("create_doc", new String[]{"$s", "@1", "@2"}));
steps.add(new ContractStep("set_property", new String[]{"$s", "catalog", "@3"}));
steps.add(new ContractStep("set_property", new String[]{"$s", "balance", "@4"}));
steps.add(new ContractStep("set_property", new String[]{"$s", "number", "@5"}));
steps.add(new ContractStep("set_property", new String[]{"$s", "available", "@6"}));
steps.add(new ContractStep("set_property", new String[]{"$s", "weight", "@7"}));
steps.add(new ContractStep("update_doc", new String[]{"@1", "$s"}));
steps.add(new ContractStep("submit"));

ContractDefine contractDefine = new ContractDefine(steps);
//check existed contract
if (conn.hasContract(contractName)) {
    //withdraw existed contract
    conn.withdrawContract(contractName);
    System.out.printf("previous contract %s removed\n", contractName);
}

//deploy contact
conn.deployContract(contractName, contractDefine);

//enable trace option
ContractInfo info = conn.getContractInfo(contractName);
if (!info.isEnabled()) {
    conn.enableContractTrace(contractName);
}

final String docID = "contract-doc";
String[] parameters = {
    schemaName,
    docID,
    schemaName,
    String.valueOf(Math.random()),
    String.valueOf((int) (Math.random() * 1000)),
    Math.random() > 0.5 ? "true" : "false",
    String.format("%.2f", Math.random() * 200)
};

//call contract with parameters
conn.callContract(createContractName, new ArrayList<>(Arrays.asList(parameters)));

检查区块链与交易

通过SDK能够获取并检查链、区块、交易的全部详细信息，用于审计数据安全性和检查后台运行情况。

//check chain status
ChainStatus status = conn.getStatus();

//query blocks from height 1 to 10
BlockRecords blockRecords = conn.queryBlocks(1, 10);
for (String blockID : blockRecords.getBlocks()) {
    //get block data
    BlockData blockData = conn.getBlock(blockID);
    //query transactions in a block
    TransactionRecords transactionRecords = conn.queryTransactions(blockID, 0, 20);
    for (String transID : transactionRecords.getTransactions()) {
        //get transaction data
        TransactionData transactionData = conn.getTransaction(blockID, transID);
    }
}