BAEL-969 Apache Commons Chain (#2228)

* BAEL 969 Apache Commons Chain - Example with testcase

* Made changes for Apache Commons Chain as per recommendation

libraries/src/main/java/com/baeldung/commons/chain/AbstractDenominationDispenser.java

@@ -0,0 +1,23 @@
+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.Command;
+import org.apache.commons.chain.Context;
+
+import static com.baeldung.commons.chain.AtmConstants.AMOUNT_LEFT_TO_BE_WITHDRAWN;
+
+public abstract class AbstractDenominationDispenser implements Command {
+
+    @Override
+    public boolean execute(Context context) throws Exception {
+        int amountLeftToBeWithdrawn = (int) context.get(AMOUNT_LEFT_TO_BE_WITHDRAWN);
+        if (amountLeftToBeWithdrawn >= getDenominationValue()) {
+            context.put(getDenominationString(), amountLeftToBeWithdrawn / getDenominationValue());
+            context.put(AMOUNT_LEFT_TO_BE_WITHDRAWN, amountLeftToBeWithdrawn % getDenominationValue());
+        }
+        return false;
+    }
+
+    protected abstract String getDenominationString();
+
+    protected abstract int getDenominationValue();
+}

libraries/src/main/java/com/baeldung/commons/chain/AtmCatalog.java

@@ -0,0 +1,13 @@
+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.impl.CatalogBase;
+
+import static com.baeldung.commons.chain.AtmConstants.ATM_WITHDRAWAL_CHAIN;
+
+public class AtmCatalog extends CatalogBase {
+
+    public AtmCatalog() {
+        super();
+        addCommand(ATM_WITHDRAWAL_CHAIN, new AtmWithdrawalChain());
+    }
+}

libraries/src/main/java/com/baeldung/commons/chain/AtmConstants.java

@@ -0,0 +1,10 @@
+package com.baeldung.commons.chain;
+
+public class AtmConstants {
+    public static final String TOTAL_AMOUNT_TO_BE_WITHDRAWN = "totalAmountToBeWithdrawn";
+    public static final String AMOUNT_LEFT_TO_BE_WITHDRAWN = "amountLeftToBeWithdrawn";
+    public static final String NO_OF_HUNDREDS_DISPENSED = "noOfHundredsDispensed";
+    public static final String NO_OF_FIFTIES_DISPENSED = "noOfFiftiesDispensed";
+    public static final String NO_OF_TENS_DISPENSED = "noOfTensDispensed";
+    public static final String ATM_WITHDRAWAL_CHAIN = "atmWithdrawalChain";
+}

libraries/src/main/java/com/baeldung/commons/chain/AtmRequestContext.java

@@ -0,0 +1,52 @@
+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.impl.ContextBase;
+
+public class AtmRequestContext extends ContextBase {
+
+    int totalAmountToBeWithdrawn;
+    int noOfHundredsDispensed;
+    int noOfFiftiesDispensed;
+    int noOfTensDispensed;
+    int amountLeftToBeWithdrawn;
+
+    public int getTotalAmountToBeWithdrawn() {
+        return totalAmountToBeWithdrawn;
+    }
+
+    public void setTotalAmountToBeWithdrawn(int totalAmountToBeWithdrawn) {
+        this.totalAmountToBeWithdrawn = totalAmountToBeWithdrawn;
+    }
+
+    public int getNoOfHundredsDispensed() {
+        return noOfHundredsDispensed;
+    }
+
+    public void setNoOfHundredsDispensed(int noOfHundredsDispensed) {
+        this.noOfHundredsDispensed = noOfHundredsDispensed;
+    }
+
+    public int getNoOfFiftiesDispensed() {
+        return noOfFiftiesDispensed;
+    }
+
+    public void setNoOfFiftiesDispensed(int noOfFiftiesDispensed) {
+        this.noOfFiftiesDispensed = noOfFiftiesDispensed;
+    }
+
+    public int getNoOfTensDispensed() {
+        return noOfTensDispensed;
+    }
+
+    public void setNoOfTensDispensed(int noOfTensDispensed) {
+        this.noOfTensDispensed = noOfTensDispensed;
+    }
+
+    public int getAmountLeftToBeWithdrawn() {
+        return amountLeftToBeWithdrawn;
+    }
+
+    public void setAmountLeftToBeWithdrawn(int amountLeftToBeWithdrawn) {
+        this.amountLeftToBeWithdrawn = amountLeftToBeWithdrawn;
+    }
+}

libraries/src/main/java/com/baeldung/commons/chain/AtmWithdrawalChain.java

@@ -0,0 +1,14 @@
+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.impl.ChainBase;
+
+public class AtmWithdrawalChain extends ChainBase {
+
+    public AtmWithdrawalChain() {
+        super();
+        addCommand(new HundredDenominationDispenser());
+        addCommand(new FiftyDenominationDispenser());
+        addCommand(new TenDenominationDispenser());
+        addCommand(new AuditFilter());
+    }
+}

libraries/src/main/java/com/baeldung/commons/chain/AuditFilter.java

@@ -0,0 +1,18 @@
+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.Context;
+import org.apache.commons.chain.Filter;
+
+public class AuditFilter implements Filter {
+
+    @Override
+    public boolean postprocess(Context context, Exception exception) {
+        //    Send notification to customer & bank.
+        return false;
+    }
+
+    @Override
+    public boolean execute(Context context) throws Exception {
+        return false;
+    }
+}

libraries/src/main/java/com/baeldung/commons/chain/FiftyDenominationDispenser.java

@@ -0,0 +1,15 @@
+package com.baeldung.commons.chain;
+
+import static com.baeldung.commons.chain.AtmConstants.NO_OF_FIFTIES_DISPENSED;
+
+public class FiftyDenominationDispenser extends AbstractDenominationDispenser {
+    @Override
+    protected String getDenominationString() {
+        return NO_OF_FIFTIES_DISPENSED;
+    }
+
+    @Override
+    protected int getDenominationValue() {
+        return 50;
+    }
+}

libraries/src/main/java/com/baeldung/commons/chain/HundredDenominationDispenser.java

@@ -0,0 +1,15 @@
+package com.baeldung.commons.chain;
+
+import static com.baeldung.commons.chain.AtmConstants.NO_OF_HUNDREDS_DISPENSED;
+
+public class HundredDenominationDispenser extends AbstractDenominationDispenser {
+    @Override
+    protected String getDenominationString() {
+        return NO_OF_HUNDREDS_DISPENSED;
+    }
+
+    @Override
+    protected int getDenominationValue() {
+        return 100;
+    }
+}

libraries/src/main/java/com/baeldung/commons/chain/TenDenominationDispenser.java

@@ -0,0 +1,15 @@
+package com.baeldung.commons.chain;
+
+import static com.baeldung.commons.chain.AtmConstants.NO_OF_TENS_DISPENSED;
+
+public class TenDenominationDispenser extends AbstractDenominationDispenser {
+    @Override
+    protected String getDenominationString() {
+        return NO_OF_TENS_DISPENSED;
+    }
+
+    @Override
+    protected int getDenominationValue() {
+        return 10;
+    }
+}