Fabric智能合约（余额转移样本）

需求分析

1）初始两个用户，赋予一定金额。

2）转账

3）查询余额

4）删除账户

---

 go语言版

项目结构

项目代码

package main

import (
	"fmt"
	"strconv"

	"github.com/hyperledger/fabric/core/chaincode/shim"
	pb "github.com/hyperledger/fabric/protos/peer"
)

var logger = shim.NewLogger("example_cc0")

// SimpleChaincode example simple Chaincode implementation
type SimpleChaincode struct {
}

// Init initializes the chaincode state
func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response {
	logger.Info("########### example_cc Init ###########")

	_, args := stub.GetFunctionAndParameters()
	var A, B string    // Entities
	var Aval, Bval int // Asset holdings
	var err error

	if len(args) != 4 {
		return shim.Error("Incorrect number of arguments. Expecting 4")
	}

	// Initialize the chaincode
	A = args[0]
	Aval, err = strconv.Atoi(args[1])
	if err != nil {
		return shim.Error("Expecting integer value for asset holding")
	}
	B = args[2]
	Bval, err = strconv.Atoi(args[3])
	if err != nil {
		return shim.Error("Expecting integer value for asset holding")
	}
	logger.Infof("Aval = %d, Bval = %d
", Aval, Bval)

	// Write the state to the ledger
	err = stub.PutState(A, []byte(strconv.Itoa(Aval)))
	if err != nil {
		return shim.Error(err.Error())
	}

	err = stub.PutState(B, []byte(strconv.Itoa(Bval)))
	if err != nil {
		return shim.Error(err.Error())
	}

	if transientMap, err := stub.GetTransient(); err == nil {

		rc := transientMap["rc"]

		transientData := transientMap["result"]

		if rc == nil {
			return shim.Success(transientData)
		}

		vrc, err := strconv.Atoi(string(rc[:]))

		if err != nil {
			return shim.Error(err.Error())
		}

		return pb.Response{
			Status:  int32(vrc),
			Payload: transientData,
		}

	}

	return shim.Success(nil)
}

// Invoke makes payment of X units from A to B
func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
	logger.Info("########### example_cc Invoke ###########")

	function, args := stub.GetFunctionAndParameters()

	if function == "delete" {
		// Deletes an entity from its state
		return t.delete(stub, args)
	}

	if function == "move" {
		// Deletes an entity from its state
		return t.move(stub, args)
	}

	if function == "query" {
		return t.query(stub, args)
	}

	logger.Errorf("Unknown action, check the first argument, must be one of 'delete', 'query', or 'move'. But got: %v", args[0])
	return shim.Error(fmt.Sprintf("Unknown action, check the first argument, must be one of 'delete', 'query', or 'move'. But got: %v", args[0]))
}

func (t *SimpleChaincode) move(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	// must be an invoke
	var A, B string    // Entities
	var Aval, Bval int // Asset holdings
	var X int          // Transaction value
	var err error

	if len(args) != 3 {
		return shim.Error("Incorrect number of arguments. Expecting 3, function followed by 2 names and 1 value")
	}

	A = args[0]
	B = args[1]

	// Get the state from the ledger
	// TODO: will be nice to have a GetAllState call to ledger
	Avalbytes, err := stub.GetState(A)
	if err != nil {
		return shim.Error("Failed to get state")
	}
	if Avalbytes == nil {
		return shim.Error("Entity not found")
	}
	Aval, _ = strconv.Atoi(string(Avalbytes))

	Bvalbytes, err := stub.GetState(B)
	if err != nil {
		return shim.Error("Failed to get state")
	}
	if Bvalbytes == nil {
		return shim.Error("Entity not found")
	}
	Bval, _ = strconv.Atoi(string(Bvalbytes))

	// Perform the execution
	X, err = strconv.Atoi(args[2])
	if err != nil {
		return shim.Error("Invalid transaction amount, expecting a integer value")
	}
	Aval = Aval - X
	Bval = Bval + X
	logger.Infof("Aval = %d, Bval = %d
", Aval, Bval)

	// Write the state back to the ledger
	err = stub.PutState(A, []byte(strconv.Itoa(Aval)))
	if err != nil {
		return shim.Error(err.Error())
	}

	err = stub.PutState(B, []byte(strconv.Itoa(Bval)))
	if err != nil {
		return shim.Error(err.Error())
	}

	if transientMap, err := stub.GetTransient(); err == nil {
		if transientData, ok := transientMap["event"]; ok {
			stub.SetEvent("event", transientData)
		}

		rc := transientMap["rc"]

		transientData := transientMap["result"]

		if rc == nil {
			return shim.Success(transientData)
		}

		vrc, err := strconv.Atoi(string(rc[:]))

		if err != nil {
			return shim.Error(err.Error())
		}


		logger.Infof("Status = %d 
", vrc)

		return pb.Response{
			Status:  int32(vrc),
			Payload: transientData,
		}
	}

	return shim.Success(nil)
}

// Deletes an entity from state
func (t *SimpleChaincode) delete(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	if len(args) != 1 {
		return shim.Error("Incorrect number of arguments. Expecting 1")
	}

	A := args[0]

	// Delete the key from the state in ledger
	err := stub.DelState(A)
	if err != nil {
		return shim.Error("Failed to delete state")
	}

	return shim.Success(nil)
}

// Query callback representing the query of a chaincode
func (t *SimpleChaincode) query(stub shim.ChaincodeStubInterface, args []string) pb.Response {

	var A string // Entities
	var err error

	if len(args) != 1 {
		return shim.Error("Incorrect number of arguments. Expecting name of the person to query")
	}

	A = args[0]

	// Get the state from the ledger
	Avalbytes, err := stub.GetState(A)
	if err != nil {
		jsonResp := "{"Error":"Failed to get state for " + A + ""}"
		return shim.Error(jsonResp)
	}

	if Avalbytes == nil {
		jsonResp := "{"Error":"Nil amount for " + A + ""}"
		return shim.Error(jsonResp)
	}

	jsonResp := "{"Name":"" + A + "","Amount":"" + string(Avalbytes) + ""}"
	logger.Infof("Query Response:%s
", jsonResp)
	return shim.Success(Avalbytes)
}

func main() {
	err := shim.Start(new(SimpleChaincode))
	if err != nil {
		logger.Errorf("Error starting Simple chaincode: %s", err)
	}
}

java语言版

项目结构

 

项目依赖

1）build.gradle文件

plugins {
    id 'com.github.johnrengelman.shadow' version '2.0.3'
    id 'java'
}

group 'org.hyperledger.fabric-chaincode-java'
version '1.0-SNAPSHOT'

sourceCompatibility = 1.8

repositories {
    mavenLocal()
    mavenCentral()
}

dependencies {
    compile group: 'org.hyperledger.fabric-chaincode-java', name: 'fabric-chaincode-shim', version: '1.4.1'
}

shadowJar {
    //这个名字必须是chaincode
    baseName = 'chaincode'
    version = null
    classifier = null

    manifest {
        attributes 'Main-Class': 'org.hyperledger.fabric.example.SimpleChaincode'
    }
}

2）settings.gradle文件

rootProject.name = 'fabric-chaincode-example-gradle'

项目代码

package org.hyperledger.fabric.example;

import java.util.List;

import com.google.protobuf.ByteString;
import io.netty.handler.ssl.OpenSsl;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hyperledger.fabric.shim.ChaincodeBase;
import org.hyperledger.fabric.shim.ChaincodeStub;

import static java.nio.charset.StandardCharsets.UTF_8;

public class SimpleChaincode extends ChaincodeBase {

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

    @Override
    public Response init(ChaincodeStub stub) {
        try {
            _logger.info("Init java simple chaincode");
            String func = stub.getFunction();
            if (!func.equals("init")) {
                return newErrorResponse("function other than init is not supported");
            }
            List<String> args = stub.getParameters();
            if (args.size() != 4) {
                newErrorResponse("Incorrect number of arguments. Expecting 4");
            }
            // Initialize the chaincode
            String account1Key = args.get(0);
            int account1Value = Integer.parseInt(args.get(1));
            String account2Key = args.get(2);
            int account2Value = Integer.parseInt(args.get(3));

            _logger.info(String.format("account %s, value = %s; account %s, value %s", account1Key, account1Value, account2Key, account2Value));
            stub.putStringState(account1Key, args.get(1));
            stub.putStringState(account2Key, args.get(3));

            return newSuccessResponse();
        } catch (Throwable e) {
            return newErrorResponse(e);
        }
    }

    @Override
    public Response invoke(ChaincodeStub stub) {
        try {
            _logger.info("Invoke java simple chaincode");
            String func = stub.getFunction();
            List<String> params = stub.getParameters();
            if (func.equals("move")) {
                return move(stub, params);
            }
            if (func.equals("delete")) {
                return delete(stub, params);
            }
            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 move(ChaincodeStub stub, List<String> args) {
        if (args.size() != 3) {
            return newErrorResponse("Incorrect number of arguments. Expecting 3");
        }
        String accountFromKey = args.get(0);
        String accountToKey = args.get(1);

        String accountFromValueStr = stub.getStringState(accountFromKey);
        if (accountFromValueStr == null) {
            return newErrorResponse(String.format("Entity %s not found", accountFromKey));
        }
        int accountFromValue = Integer.parseInt(accountFromValueStr);

        String accountToValueStr = stub.getStringState(accountToKey);
        if (accountToValueStr == null) {
            return newErrorResponse(String.format("Entity %s not found", accountToKey));
        }
        int accountToValue = Integer.parseInt(accountToValueStr);

        int amount = Integer.parseInt(args.get(2));

        if (amount > accountFromValue) {
            return newErrorResponse(String.format("not enough money in account %s", accountFromKey));
        }

        accountFromValue -= amount;
        accountToValue += amount;

        _logger.info(String.format("new value of A: %s", accountFromValue));
        _logger.info(String.format("new value of B: %s", accountToValue));

        stub.putStringState(accountFromKey, Integer.toString(accountFromValue));
        stub.putStringState(accountToKey, Integer.toString(accountToValue));

        _logger.info("Transfer complete");

        return newSuccessResponse("invoke finished successfully", ByteString.copyFrom(accountFromKey + ": " + accountFromValue + " " + accountToKey + ": " + accountToValue, UTF_8).toByteArray());
    }

    // Deletes an entity from state
    private Response delete(ChaincodeStub stub, List<String> args) {
        if (args.size() != 1) {
            return newErrorResponse("Incorrect number of arguments. Expecting 1");
        }
        String key = args.get(0);
        // Delete the key from the state in ledger
        stub.delState(key);
        return newSuccessResponse();
    }

    // query callback representing the query of a chaincode
    private Response query(ChaincodeStub stub, List<String> 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:
Name: %s, Amount: %s
", 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 SimpleChaincode().start(args);
    }
}