Add TypeAdapterFactory support to @JsonAdapter.

vagrant1991 · Aug 4, 2014 · 29bbc9b · 29bbc9b
1 parent 225a6c3
commit 29bbc9b
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Showing 5 changed files with 103 additions and 17 deletions.
diff --git a/gson/src/main/java/com/google/gson/annotations/JsonAdapter.java b/gson/src/main/java/com/google/gson/annotations/JsonAdapter.java
@@ -16,13 +16,13 @@
 
 package com.google.gson.annotations;
 
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-import com.google.gson.TypeAdapter;
-
 /**
  * An annotation that indicates the Gson {@link TypeAdapter} to use with a class
  * or field.
@@ -87,6 +87,7 @@
 @Target({ElementType.TYPE, ElementType.FIELD})
 public @interface JsonAdapter {
 
-  Class<? extends TypeAdapter<?>> value();
+  /** Either a {@link TypeAdapter} or {@link TypeAdapterFactory}. */
+  Class<?> value();
 
 }
diff --git a/.../src/main/java/com/google/gson/internal/bind/JsonAdapterAnnotationTypeAdapterFactory.java b/.../src/main/java/com/google/gson/internal/bind/JsonAdapterAnnotationTypeAdapterFactory.java
@@ -21,7 +21,6 @@
 import com.google.gson.TypeAdapterFactory;
 import com.google.gson.annotations.JsonAdapter;
 import com.google.gson.internal.ConstructorConstructor;
-import com.google.gson.internal.ObjectConstructor;
 import com.google.gson.reflect.TypeToken;
 
 /**
@@ -41,8 +40,28 @@ public JsonAdapterAnnotationTypeAdapterFactory(ConstructorConstructor constructo
   @SuppressWarnings({"rawtypes", "unchecked"})
   public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> targetType) {
     JsonAdapter annotation = targetType.getRawType().getAnnotation(JsonAdapter.class);
-    return annotation != null
-        ? (TypeAdapter<T>) constructorConstructor.get(TypeToken.get(annotation.value())).construct()
-        : null;
+    if (annotation == null) {
+      return null;
+    }
+    return (TypeAdapter<T>) getTypeAdapter(constructorConstructor, gson, targetType, annotation);
+  }
+
+  @SuppressWarnings("unchecked") // Casts guarded by conditionals.
+  static TypeAdapter<?> getTypeAdapter(ConstructorConstructor constructorConstructor, Gson gson,
+      TypeToken<?> fieldType, JsonAdapter annotation) {
+    Class<?> value = annotation.value();
+    if (TypeAdapter.class.isAssignableFrom(value)) {
+          Class<TypeAdapter<?>> typeAdapter = (Class<TypeAdapter<?>>) value;
+      return constructorConstructor.get(TypeToken.get(typeAdapter)).construct();
+    }
+    if (TypeAdapterFactory.class.isAssignableFrom(value)) {
+          Class<TypeAdapterFactory> typeAdapterFactory = (Class<TypeAdapterFactory>) value;
+      return constructorConstructor.get(TypeToken.get(typeAdapterFactory))
+          .construct()
+          .create(gson, fieldType);
+    }
+
+    throw new IllegalArgumentException(
+        "@JsonAdapter value must be TypeAdapter or TypeAdapterFactory reference.");
   }
 }
diff --git a/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java b/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
@@ -38,6 +38,8 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import static com.google.gson.internal.bind.JsonAdapterAnnotationTypeAdapterFactory.getTypeAdapter;
+
 /**
  * Type adapter that reflects over the fields and methods of a class.
  */
@@ -100,9 +102,11 @@ private ReflectiveTypeAdapterFactory.BoundField createBoundField(
 
   private TypeAdapter<?> getFieldAdapter(Gson gson, Field field, TypeToken<?> fieldType) {
     JsonAdapter annotation = field.getAnnotation(JsonAdapter.class);
-    return (annotation != null)
-        ? constructorConstructor.get(TypeToken.get(annotation.value())).construct()
-        : gson.getAdapter(fieldType);
+    if (annotation != null) {
+      TypeAdapter<?> adapter = getTypeAdapter(constructorConstructor, gson, fieldType, annotation);
+      if (adapter != null) return adapter;
+    }
+    return gson.getAdapter(fieldType);
   }
 
   private Map<String, BoundField> getBoundFields(Gson context, TypeToken<?> type, Class<?> raw) {

diff --git a/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnClassesTest.java b/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnClassesTest.java
@@ -16,11 +16,6 @@
 
 package com.google.gson.functional;
 
-import java.io.IOException;
-import java.lang.reflect.Type;
-
-import junit.framework.TestCase;
-
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonDeserializationContext;
@@ -31,9 +26,14 @@
 import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
 import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.reflect.TypeToken;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.lang.reflect.Type;
+import junit.framework.TestCase;
 
 /**
  * Functional tests for the {@link com.google.gson.annotations.JsonAdapter} annotation on classes.
@@ -53,6 +53,14 @@ public void testJsonAdapterInvoked() {
     assertEquals("Leitch", user.lastName);
   }
 
+  public void testJsonAdapterFactoryInvoked() {
+    Gson gson = new Gson();
+    String json = gson.toJson(new C("bar"));
+    assertEquals("\"jsonAdapterFactory\"", json);
+    C c = gson.fromJson("\"bar\"", C.class);
+    assertEquals("jsonAdapterFactory", c.value);
+  }
+
   public void testRegisteredAdapterOverridesJsonAdapter() {
     TypeAdapter<A> typeAdapter = new TypeAdapter<A>() {
       @Override public void write(JsonWriter out, A value) throws IOException {
@@ -125,7 +133,7 @@ private static class A {
     A(String value) {
       this.value = value;
     }
-    private static final class JsonAdapter extends TypeAdapter<A> { 
+    static final class JsonAdapter extends TypeAdapter<A> {
       @Override public void write(JsonWriter out, A value) throws IOException {
         out.value("jsonAdapter");
       }
@@ -136,6 +144,27 @@ private static final class JsonAdapter extends TypeAdapter<A> {
     }
   }
 
+  @JsonAdapter(C.JsonAdapterFactory.class)
+  private static class C {
+    final String value;
+    C(String value) {
+      this.value = value;
+    }
+    static final class JsonAdapterFactory implements TypeAdapterFactory {
+      public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) {
+        return new TypeAdapter<T>() {
+          @Override public void write(JsonWriter out, T value) throws IOException {
+            out.value("jsonAdapterFactory");
+          }
+          @Override public T read(JsonReader in) throws IOException {
+            in.nextString();
+            return (T) new C("jsonAdapterFactory");
+          }
+        };
+      }
+    }
+  }
+
   private static final class B extends A {
     B(String value) {
       super(value);

diff --git a/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnFieldsTest.java b/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnFieldsTest.java
@@ -19,7 +19,9 @@
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
 import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.reflect.TypeToken;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
 import java.io.IOException;
@@ -37,6 +39,14 @@ public void testClassAnnotationAdapterTakesPrecedenceOverDefault() {
     assertEquals("UserClassAnnotationAdapter", computer.user.name);
   }
 
+  public void testClassAnnotationAdapterFactoryTakesPrecedenceOverDefault() {
+    Gson gson = new Gson();
+    String json = gson.toJson(new Gizmo(new Part("Part")));
+    assertEquals("{\"part\":\"GizmoPartTypeAdapterFactory\"}", json);
+    Gizmo computer = gson.fromJson("{'part':'Part'}", Gizmo.class);
+    assertEquals("GizmoPartTypeAdapterFactory", computer.part.name);
+  }
+
   public void testRegisteredTypeAdapterTakesPrecedenceOverClassAnnotationAdapter() {
     Gson gson = new GsonBuilder()
         .registerTypeAdapter(User.class, new RegisteredUserAdapter())
@@ -80,9 +90,17 @@ private static final class Gadget {
     }
   }
 
+  private static final class Gizmo {
+    @JsonAdapter(GizmoPartTypeAdapterFactory.class)
+    final Part part;
+    Gizmo(Part part) {
+      this.part = part;
+    }
+  }
+
   private static final class Part {
     final String name;
-    Part(String name) {
+    public Part(String name) {
       this.name = name;
     }
   }
@@ -97,6 +115,21 @@ private static class PartJsonFieldAnnotationAdapter extends TypeAdapter<Part> {
     }
   }
 
+  private static class GizmoPartTypeAdapterFactory implements TypeAdapterFactory {
+    public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) {
+      return new TypeAdapter<T>() {
+        @Override public void write(JsonWriter out, T value) throws IOException {
+          out.value("GizmoPartTypeAdapterFactory");
+        }
+        @SuppressWarnings("unchecked")
+        @Override public T read(JsonReader in) throws IOException {
+          in.nextString();
+          return (T) new Part("GizmoPartTypeAdapterFactory");
+        }
+      };
+    }
+  }
+
   private static final class Computer {
     final User user;
     Computer(User user) {