hyperledger java_hyperledger fabric 1.4 使用java开发智能合约

hyperledger fabric使用java开发智能合约，也较为简单，我们今天就来聊一聊如何使用java开发智能合约，如需完整的学习fabric，可以参考视频教程

首先需要在pom里面引入fabric的智能合约的jar包，如下图所示，需要注意的点如下，引入maven-shade-plugin包，设置mainclass，且finalname必须为chaincode。

org.hyperledger.fabric-chaincode-java

fabric-chaincode-shim

1.4.0

org.apache.maven.plugins

maven-compiler-plugin

3.1

${java.version}

${java.version}

org.apache.maven.plugins

maven-shade-plugin

3.1.0

package

shade

chaincode

com.fabric.chaincode.MyChaincode

*:*

META-INF/*.SF

META-INF/*.DSA

META-INF/*.RSA

java-fabric的示例代码如下：~~~~

private static Log _logger = LogFactory.getLog(MyChaincode.class);

@Override

public Response init(ChaincodeStub stub) {

return newSuccessResponse();

}

@Override

public Response invoke(ChaincodeStub stub) {

try {

_logger.info("Invoke java simple chaincode");

String func = stub.getFunction();

List params = stub.getParameters();

if (func.equals("invoke")) {

return invoke(stub, params);

}

else if (func.equals("query")) {

return query(stub, params);

}

return newErrorResponse("Invalid invoke function name. Expecting one of: [\"invoke\", \"delete\", \"query\"]");

} catch (Throwable e) {

return newErrorResponse(e);

}

}

private Response invoke(ChaincodeStub stub, List args) {

if (args.size() != 2) {

return newErrorResponse("Incorrect number of arguments. Expecting 3");

}

String key = args.get(0);

String json = args.get(1);

if(StringUtil.isNullOrEmpty(key) || StringUtil.isNullOrEmpty(json)){

return newErrorResponse("arguments error");

}else{

stub.putStringState(key,json);

return newSuccessResponse("put success!");

}

}

// query callback representing the query of a chaincode

private Response query(ChaincodeStub stub, List args) {

if (args.size() != 1) {

return newErrorResponse("Incorrect number of arguments. Expecting name of the person to query");

}

String key = args.get(0);

//byte[] stateBytes

String val = stub.getStringState(key);

if (val == null) {

return newErrorResponse(String.format("Error: state for %s is null", key));

}

_logger.info(String.format("Query Response:\nName: %s, Amount: %s\n", key, val));

return newSuccessResponse(val, ByteString.copyFrom(val, UTF_8).toByteArray());

}

public static void main(String[] args) {

System.out.println("OpenSSL avaliable: " + OpenSsl.isAvailable());

new MyChaincode().start(args);

}

}

智能合约的安装和实例化,需要注意的是 -l java指定java语言为智能合约，智能合约的路径需要补全，go开发的话无需补全。

peer chaincode install -n jcode -v 1.0 -p /opt/gopath/src//chaincode/javachaincode/ -l java

peer chaincode instantiate -o :7050 --tls --cafile /opt/gopath/src//hyperledger/fabric/peer/crypto/ordererOrganizations//orderers//msp/tlscacerts/-cert.pem -C mychannel -n jcode -v 1.0 -c '{"Args":["init"]}' -P "AND ('Org1MSP.peer')"