bug fixed for WildcardType extends Generic Type. issue #998

src/main/java/com/alibaba/fastjson/parser/deserializer/ArrayListTypeFieldDeserializer.java

@@ -3,6 +3,7 @@
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
+import java.lang.reflect.WildcardType;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Map;
@@ -27,7 +28,15 @@ public ArrayListTypeFieldDeserializer(ParserConfig mapping, Class<?> clazz, Fiel
 
         Type fieldType = fieldInfo.fieldType;
         if (fieldType instanceof ParameterizedType) {
-            this.itemType = ((ParameterizedType) fieldInfo.fieldType).getActualTypeArguments()[0];
+            Type argType = ((ParameterizedType) fieldInfo.fieldType).getActualTypeArguments()[0];
+            if (argType instanceof WildcardType) {
+                WildcardType wildcardType = (WildcardType) argType;
+                Type[] upperBounds = wildcardType.getUpperBounds();
+                if (upperBounds.length == 1) {
+                    argType = upperBounds[0];
+                }
+            }
+            this.itemType = argType;
         } else {
             this.itemType = Object.class;
         }

src/test/java/com/alibaba/json/bvt/bug/Issue998.java

@@ -0,0 +1,28 @@
+package com.alibaba.json.bvt.bug;
+
+import com.alibaba.fastjson.JSON;
+import com.alibaba.fastjson.TypeReference;
+import junit.framework.TestCase;
+
+import java.util.List;
+
+/**
+ * Created by wenshao on 16/01/2017.
+ */
+public class Issue998 extends TestCase {
+    public void test_for_issue() throws Exception {
+        Model model = JSON.parseObject("{\"items\":[{\"id\":123}]}", Model.class);
+        assertNotNull(model);
+        assertNotNull(model.items);
+        assertEquals(1, model.items.size());
+        assertEquals(123, model.items.get(0).id);
+    }
+
+    public static class Model {
+        public List<? extends Item> items;
+    }
+
+    public static class Item {
+        public int id;
+    }
+}