GenericData can now overload setters (#538)

* Fix #340 HttpHeaders won't let me put/set "accept"

* fix case of null value

Author: ajaaym

google-http-client/src/main/java/com/google/api/client/util/FieldInfo.java

@@ -15,8 +15,12 @@
 package com.google.api.client.util;
 
 import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
 import java.util.WeakHashMap;
 
@@ -112,6 +116,9 @@ public static FieldInfo of(Field field) {
   /** Field. */
   private final Field field;
 
+  /** Setters Method for field */
+  private final Method []setters;
+
   /**
    * Data key name associated with the field for a non-enum-constant with a {@link Key} annotation,
    * or data key value associated with the enum constant with a {@link Value} annotation or {@code
@@ -127,6 +134,21 @@ public static FieldInfo of(Field field) {
     this.field = field;
     this.name = name == null ? null : name.intern();
     isPrimitive = Data.isPrimitive(getType());
+    this.setters = settersMethodForField(field);
+  }
+
+  /**
+   * Creates list of setter methods for a field only in declaring class.
+   */
+  private Method[] settersMethodForField(Field field) {
+    List<Method> methods = new ArrayList<Method>();
+    for (Method method : field.getDeclaringClass().getDeclaredMethods()) {
+      if (method.getName().toLowerCase().equals("set" + field.getName().toLowerCase())
+          && method.getParameterTypes().length == 1) {
+        methods.add(method);
+      }
+    }
+    return methods.toArray(new Method[methods.size()]);
   }
 
   /**
@@ -203,6 +225,20 @@ public Object getValue(Object obj) {
    * If the field is final, it checks that value being set is identical to the existing value.
    */
   public void setValue(Object obj, Object value) {
+    if (setters.length > 0) {
+      for (Method method : setters) {
+        if (value == null || method.getParameterTypes()[0].isAssignableFrom(value.getClass())) {
+          try {
+            method.invoke(obj, value);
+            return;
+          } catch (IllegalAccessException e) {
+            // try to set field directly
+          } catch (InvocationTargetException e) {
+            // try to set field directly
+          }
+        }
+      }
+    }
     setFieldValue(field, obj, value);
   }
 

google-http-client/src/test/java/com/google/api/client/util/GenericDataTest.java

@@ -15,7 +15,9 @@
 package com.google.api.client.util;
 
 import com.google.api.client.util.GenericData.Flags;
+import java.util.ArrayList;
 import java.util.EnumSet;
+import java.util.List;
 import junit.framework.Assert;
 import junit.framework.TestCase;
 
@@ -32,6 +34,18 @@ public MyData() {
 
     @Key("FieldA")
     public String fieldA;
+
+    @Key("FieldB")
+    public List<String> fieldB;
+
+    public void setFieldB(String fieldB) {
+      this.fieldB = Lists.newArrayList();
+      this.fieldB.add(fieldB);
+    }
+
+    public void setFieldB(List<String> fieldB) {
+      this.fieldB = fieldB;
+    }
   }
 
 
@@ -119,4 +133,14 @@ public void testRemoveIgnoreCase_unknownKey() {
     assertEquals(2, data.remove("TESTA"));
     assertEquals(null, data.remove("TESTA"));
   }
+
+  public void testPutShouldUseSetter() {
+    MyData data = new MyData();
+    data.put("fieldB", "value1");
+    assertEquals("value1", data.fieldB.get(0));
+    List<String> list = new ArrayList();
+    list.add("value2");
+    data.put("fieldB", list);
+    assertEquals(list, data.fieldB);
+  }
 }