Fixed issue 87 by adding support for deserialization of java.util.Properties

gson/src/main/java/com/google/gson/DefaultTypeAdapters.java

@@ -36,6 +36,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Properties;
 import java.util.Queue;
 import java.util.Set;
 import java.util.SortedSet;
@@ -77,6 +78,7 @@ final class DefaultTypeAdapters {
   private static final ShortTypeAdapter SHORT_TYPE_ADAPTER = new ShortTypeAdapter();
   private static final StringTypeAdapter STRING_TYPE_ADAPTER = new StringTypeAdapter();
 
+  private static final PropertiesCreator PROPERTIES_CREATOR = new PropertiesCreator();
   private static final TreeSetCreator TREE_SET_CREATOR = new TreeSetCreator();
 
   // The constants DEFAULT_SERIALIZERS, DEFAULT_DESERIALIZERS, and DEFAULT_INSTANCE_CREATORS
@@ -173,6 +175,7 @@ final class DefaultTypeAdapters {
 
     map.register(Set.class, TREE_SET_CREATOR);
     map.register(SortedSet.class, TREE_SET_CREATOR);
+    map.register(Properties.class, PROPERTIES_CREATOR);
     map.makeUnmodifiable();
     return map;
   }
@@ -445,6 +448,12 @@ final class DefaultTypeAdapters {
     }    
   }
   
+  static class PropertiesCreator implements InstanceCreator<Properties> {
+    public Properties createInstance(Type type) {
+      return new Properties();
+    }    
+  }
+  
   @SuppressWarnings("unchecked")
   static class MapTypeAdapter implements JsonSerializer<Map>, JsonDeserializer<Map>,
       InstanceCreator<Map> {

gson/src/main/java/com/google/gson/TypeInfoMap.java

@@ -19,6 +19,7 @@ package com.google.gson;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.util.Map;
+import java.util.Properties;
 
 /**
  * A convenience object for retrieving the map type information.
@@ -27,24 +28,31 @@ import java.util.Map;
  * @author Joel Leitch
  */
 final class TypeInfoMap {
-  private final ParameterizedType mapType;
+  private final Type keyType;
+  private final Type valueType;
   
   public TypeInfoMap(Type mapType) {
-    if (!(mapType instanceof ParameterizedType)) {
+    if (mapType instanceof Class && Properties.class.isAssignableFrom((Class<?>) mapType)) {
+      keyType = String.class;
+      valueType = String.class;
+    } else if (mapType instanceof ParameterizedType) {
+      TypeInfo rawType = new TypeInfo(mapType);
+      Preconditions.checkArgument(Map.class.isAssignableFrom(rawType.getRawClass()));
+      ParameterizedType paramType = (ParameterizedType) mapType;
+      keyType = paramType.getActualTypeArguments()[0];
+      valueType = paramType.getActualTypeArguments()[1];      
+    } else {
       throw new IllegalArgumentException(
           "Map objects need to be parameterized unless you use a custom serializer. "
               + "Use the com.google.gson.reflect.TypeToken to extract the ParameterizedType.");
     }
-    TypeInfo rawType = new TypeInfo(mapType);
-    Preconditions.checkArgument(Map.class.isAssignableFrom(rawType.getRawClass()));
-    this.mapType = (ParameterizedType) mapType;
   }
 
   public Type getKeyType() {
-    return mapType.getActualTypeArguments()[0];
+    return keyType;
   }
 
   public Type getValueType() {
-    return mapType.getActualTypeArguments()[1];
+    return valueType;
   }
 }

gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java

@@ -262,7 +262,7 @@ public class DefaultTypeAdaptersTest extends TestCase {
   
   public void testPropertiesSerialization() {
     Properties props = new Properties();
-    props.put("foo", "bar");
+    props.setProperty("foo", "bar");
     String json = gson.toJson(props);
     System.out.println(json);
   }
@@ -270,6 +270,6 @@ public class DefaultTypeAdaptersTest extends TestCase {
   public void testPropertiesDeserialization() {
     String json = "{foo:'bar'}";
     Properties props = gson.fromJson(json, Properties.class);
-    assertEquals("bar", props.get("foo"));
+    assertEquals("bar", props.getProperty("foo"));
   }
 }