CordaにおけるReference Stateの活用方法(コード解説編)

    private static int ID_AddressState=1;
    @NotNull
    private final Party issuer;
    @NotNull
    private final String address;
    @NotNull
    private final UniqueIdentifier linearId;

      //1. About InputState
      require.using("No Address InputState should be consumed when publishing Address State",
              tx.inputsOfType(AddressState.class).isEmpty());

      //2. About OutputState
      final List<AddressState> outList=tx.outputsOfType(AddressState.class);
      require.using("Only one OutputState should be created",
              outList.size()==1);

     List<AddressState> inputState=tx.inputsOfType(AddressState.class);
     List<AddressState> outputState=tx.outputsOfType(AddressState.class);

     //add constraints regarding Move command.
     //1. About InputState and OutputState
     require.using("Move transaction should only consume and create one InputState and One OutputState.",
             inputState.size()==1 &&
             outputState.size()==1);

     //2. About Address information
     require.using("Address information should be changed in Move transaction",
             !(inputState.get(0).getAddress()).equals(outputState.get(0).getAddress()));

     //3. Other fields should not be changed.
     require.using("Only address field should be changed in Move transaction",
             inputState.get(0).getIssuer().equals(outputState.get(0).getIssuer()) &&
             inputState.get(0).getLinearId().equals(outputState.get(0).getLinearId()));

     //2. Add outputState and Command into TX.
     AddressState state=new AddressState(getServiceHub().getMyInfo().getLegalIdentities().get(0), address);
              Command txCommand=new Command(new 
     AddressContract.Commands.Publish(),getServiceHub().getMyInfo().getLegalIdentities().get(0).getOwningKey());
              TransactionBuilder txBuilder=new TransactionBuilder(notary)
                    .addOutputState(state, AddressContract.ADDRESS_CONTRACT_ID)
                    .addCommand(txCommand);

     //2. Find already published AddressState.
     StateAndRef<AddressState> oldState=getServiceHub().getVaultService().queryBy(AddressState.class).getStates().get(0);
     AddressState oldStateData=oldState.getState().getData();
     String newAddress=address;
     AddressState newAddressState=new AddressState(
              oldStateData.getIssuer(),
              newAddress,
              oldStateData.getLinearId()
     );

     private int ID_Contract=1;

     //whether matches IOU lender and AddressState issuer.
     AddressState addressState =tx.referenceInputRefsOfType(AddressState.class).get(0).getState().getData();
     require.using("The lender of IOUState and the issuer of AddressState should be matched.",addressState.getIssuer().equals(outputState.getBorrower()));

                //ID constraints
     require.using("ID_AddressState and ID_Contract must be same.",ID_Contract==AddressState.getID_AddressState());

       public StateAndRef<AddressState> getAddressIssuer(Party addressStateIssuer){
			Predicate<StateAndRef<AddressState>> byIssuer=addressISU
					->(addressISU.getState().getData().getIssuer().equals(addressStateIssuer));
			List<StateAndRef<AddressState>> addressLists = getServiceHub().getVaultService().queryBy(AddressState.class)
					.getStates().stream().filter(byIssuer).collect(Collectors.toList());
			if(addressLists.isEmpty()){
				return null;
			}else{
				return addressLists.get(0);
			}
		}

            //1. get latest AddressState's hash by using vaultQuery.
			QueryCriteria queryCriteria=new QueryCriteria.VaultQueryCriteria(Vault.StateStatus.ALL);
			Vault.Page results =getServiceHub().getVaultService().queryBy(AddressState.class,queryCriteria);
			//The index is set to 1 to see the item of "ref".
			StateAndRef included_addressState=(StateAndRef) results.getStates().get(1);
			SecureHash vault_addressHash=included_addressState.getRef().getTxhash();

			//2. get previous AddressState's hash by using validatedTransaction.
			StateRef results1 =getServiceHub().getValidatedTransactions().getTransaction(vault_addressHash).getInputs().get(0);
			SecureHash previousHash=results1.getTxhash();
			//Output previous hash to confirm.
			System.out.println("previousHash="+previousHash);

     public StateAndRef<AddressState> getAddressContent(SecureHash previousHash){
			QueryCriteria queryCriteria=new QueryCriteria.VaultQueryCriteria(Vault.StateStatus.ALL);
			//search the hash equal to the previous hash and put it in the list.
			Predicate<StateAndRef<AddressState>> byHash=address_hash
					->(address_hash.getRef().getTxhash().equals(previousHash));
			List<StateAndRef<AddressState>> addressHashLists=getServiceHub().getVaultService().queryBy(AddressState.class,queryCriteria)
					.getStates().stream().filter(byHash).collect(Collectors.toList());
			//Output previous hash to confirm.
			System.out.println("the content of list="+ addressHashLists);
			if(addressHashLists.isEmpty()){
				return null;
			}else{
				return addressHashLists.get(0);
			}
		}