Implement Symbol Aliases

unit-api-core/src/main/java/com/raynigon/unit/api/core/units/general/IUnit.java

@@ -9,6 +9,16 @@ public interface IUnit<Q extends Quantity<Q>> extends Unit<Q> {
 
     Class<Q> getQuantityType();
 
+    /**
+     * Symbol aliases which are also accepted for parsing.
+     * This is needed because some units have multiple commonly used symbols.
+     * One example is the Newton meter which is commonly written as "N m" or "N⋅m".
+     * Another one is the degree Celsius which is commonly written as "°C" or "℃".
+     */
+    default String[] getSymbolAliases() {
+        return new String[]{};
+    }
+
     default boolean isSystemUnit() {
         return getSystemUnit().getClass().equals(this.getClass());
     }

unit-api-core/src/main/java/com/raynigon/unit/api/core/units/general/UnitScanUtils.java

@@ -38,7 +38,7 @@ private static Object createInstance(Constructor<?> it) {
         try {
             return it.newInstance();
         } catch (Exception e) {
-            log.error("Unable to create Unit Instance for " + it.getName(), e);
+            log.error("Unable to create Unit Instance for {}", it.getName(), e);
             return null;
         }
     }

unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/SISystem.java

@@ -13,57 +13,61 @@
 import javax.measure.Unit;
 import javax.measure.spi.SystemOfUnits;
 
 public class SISystem implements SystemOfUnits {
 
   public static final String ID = "SI";
 
   private final Set<IUnit<?>> units = new HashSet<>();
 
   private final Map<Class<?>, IUnit<?>> systemUnits = new HashMap<>();
 
   private final Map<String, IUnit<?>> symbolToUnit = new HashMap<>();
 
   public SISystem() {
     init();
   }
 
   private void init() {
     UnitScanUtils.scanForUnits(SISystem.class.getPackage()).forEach(this::addUnit);
   }
 
   private void addUnit(IUnit<?> unit) {
     this.units.add(unit);
     symbolToUnit.put(unit.getSymbol(), unit);
+    // Add Symbols Aliases for Parsing
+    for (String alias : unit.getSymbolAliases()) {
+      symbolToUnit.put(alias, unit);
+    }
     if (unit.isSystemUnit()) {
       systemUnits.put(unit.getQuantityType(), unit);
     }
   }
 
   @Override
   public String getName() {
     return ID;
   }
 
   @Override
   public <Q extends Quantity<Q>> Unit<Q> getUnit(Class<Q> quantityType) {
     //noinspection unchecked
     return (Unit<Q>) systemUnits.get(quantityType);
   }
 
   @Override
   public IUnit<?> getUnit(String symbol) {
     return symbolToUnit.get(symbol);
   }
 
   @Override
   public Set<? extends IUnit<?>> getUnits() {
     return Collections.unmodifiableSet(this.units);
   }
 
   @Override
   public Set<? extends IUnit<?>> getUnits(Dimension dimension) {
     return this.units.stream()
         .filter(unit -> unit.getDimension().equals(dimension))
         .collect(Collectors.toSet());
   }
 }

unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/temperature/Celsius.java

@@ -7,25 +7,30 @@
 
 import javax.measure.quantity.Temperature;
 
 public class Celsius extends TransformedUnit<Temperature> implements IUnit<Temperature> {
 
   @SuppressWarnings("unchecked")
   public Celsius() {
     super(
-            "\u2103",
+            "°C",
             "Celsius",
             new Kelvin(),
             new Kelvin(),
             AddConverter.of(273.15));
   }
 
   @Override
   public String getSystemId() {
     return SISystem.ID;
   }
 
   @Override
   public Class<Temperature> getQuantityType() {
     return Temperature.class;
   }
+
+    @Override
+    public String[] getSymbolAliases() {
+        return new String[]{"\u2103"};
+    }
 }

unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/torque/NewtonMetre.java

@@ -8,10 +8,18 @@
 
 import javax.measure.Unit;
 
 public class NewtonMetre extends AlternateUnit<Torque> {
 
     @SuppressWarnings("unchecked")
     public NewtonMetre() {
-        super(SISystem.ID, "Nm", "Newton Metre", (Unit<Torque>) new Newton().multiply(new Metre()), Torque.class);
+        super(SISystem.ID, "N m", "Newton Metre", (Unit<Torque>) new Newton().multiply(new Metre()), Torque.class);
+    }
+
+    @Override
+    public String[] getSymbolAliases() {
+        return new String[]{
+                "N⋅m", // UTF-8 Middle Dot
+                "N·m"  // UTF-8 Interpunct
+        };
     }
 }

unit-api-core/src/test/groovy/com/raynigon/unit/api/core/units/si/SISystemSpec.groovy

@@ -1,5 +1,6 @@
 package com.raynigon.unit.api.core.units.si
 
+import com.raynigon.unit.api.core.service.UnitsApiService
 import com.raynigon.unit.api.core.units.si.acceleration.MetrePerSquaredSecond
 import com.raynigon.unit.api.core.units.si.energy.Joule
 import com.raynigon.unit.api.core.units.si.energy.KiloWattHour
@@ -17,12 +18,10 @@ import com.raynigon.unit.api.core.units.si.temperature.Kelvin
 import com.raynigon.unit.api.core.units.si.time.Hour
 import com.raynigon.unit.api.core.units.si.time.Minute
 import com.raynigon.unit.api.core.units.si.time.Second
+import com.raynigon.unit.api.core.units.si.torque.NewtonMetre
 import spock.lang.Specification
 import spock.lang.Unroll
 
-import static com.raynigon.unit.api.core.service.UnitsApiService.quantity
-
-
 class SISystemSpec extends Specification {
 
     @Unroll
@@ -59,54 +58,59 @@ class SISystemSpec extends Specification {
         "km/h"   | new KilometrePerHour()
         // temperature
         "K"      | new Kelvin()
+        "°C"     | new Celsius()
         "\u2103" | new Celsius()
         // time
         "s"      | new Second()
         "min"    | new Minute()
         "h"      | new Hour()
+        // torque
+        "N m"    | new NewtonMetre()
+        "N·m"    | new NewtonMetre()
+        "N⋅m"    | new NewtonMetre()
     }
 
     def 'metre conversion'() {
 
         when:
-        def quantity = quantity(initialValue, unit)
+        def quantity = UnitsApiService.quantity(initialValue, unit)
 
         then:
         expectedValue == quantity.to(new Metre()).value.intValue()
 
         where:
         unit             | initialValue | expectedValue
-        new Metre()      | 1    | 1
-        new Millimetre() | 1000 | 1
-        new Kilometre()  | 1    | 1000
+        new Metre()      | 1            | 1
+        new Millimetre() | 1000         | 1
+        new Kilometre()  | 1            | 1000
     }
 
     def 'energy conversion'() {
 
         when:
-        def quantity = quantity(initialValue, unit)
+        def quantity = UnitsApiService.quantity(initialValue, unit)
 
         then:
         expectedValue == quantity.to(new Joule()).value.intValue()
 
         where:
         unit               | initialValue | expectedValue
-        new Joule()        | 1 | 1
-        new WattHour()     | 1 | 3600
-        new KiloWattHour() | 1 | 3600000
+        new Joule()        | 1            | 1
+        new WattHour()     | 1            | 3600
+        new KiloWattHour() | 1            | 3600000
     }
 
     def 'speed conversion'() {
 
         when:
-        def quantity = quantity(initialValue, unit)
+        def quantity = UnitsApiService.quantity(initialValue, unit)
 
         then:
         expectedValue == quantity.to(new MetrePerSecond()).value.intValue()
 
         where:
         unit                   | initialValue | expectedValue
-        new MetrePerSecond()   | 1  | 1
-        new KilometrePerHour() | 36 | 10
+        new MetrePerSecond()   | 1            | 1
+        new KilometrePerHour() | 36           | 10
     }
 }

unit-api-jackson/src/test/groovy/com/raynigon/unit/api/jackson/serializer/QuantitySerializerSpec.groovy

@@ -126,7 +126,7 @@ class QuantitySerializerSpec extends Specification {
         noExceptionThrown()
 
         and:
-        result == '{"id":"1","temperature":"30 ℃"}'
+        result == '{"id":"1","temperature":"30 °C"}'
     }
 
     def 'object deserialization'() {