Hyperledger Fabric java如何使用getQueryResult()

import org.hyperledger.fabric.shim.ChaincodeStub;
import org.hyperledger.fabric.shim.ledger.QueryResultsIterator;
import org.hyperledger.fabric.shim.ledger.KeyValue;

public String queryData(ChaincodeStub stub, String query) {
    QueryResultsIterator<KeyValue> results = stub.getQueryResult(query);
    StringBuilder response = new StringBuilder();

    for (KeyValue kv : results) {
        response.append(kv.getStringValue());
        response.append(",");
    }

    return response.toString();
}

public Response invoke(ChaincodeStub stub) {
    String function = stub.getFunction();
    List<String> args = stub.getParameters();

    if (function.equals("queryData")) {
        if (args.size() != 1) {
            return newErrorResponse("Incorrect number of arguments. Expecting 1");
        }

        String query = args.get(0);
        String result = queryData(stub, query);

        return newSuccessResponse(result);
    }

    return newErrorResponse("Invalid function name");
}