#581 Type parameter resolution should work on fields as well.

Author: harawata

src/main/java/org/apache/ibatis/reflection/Reflector.java

@@ -275,14 +275,16 @@ private void addFields(Class<?> clazz) {
   private void addSetField(Field field) {
     if (isValidPropertyName(field.getName())) {
       setMethods.put(field.getName(), new SetFieldInvoker(field));
-      setTypes.put(field.getName(), field.getType());
+      Type fieldType = TypeParameterResolver.resolveFieldType(field, type);
+      setTypes.put(field.getName(), typeToClass(fieldType));
     }
   }
 
   private void addGetField(Field field) {
     if (isValidPropertyName(field.getName())) {
       getMethods.put(field.getName(), new GetFieldInvoker(field));
-      getTypes.put(field.getName(), field.getType());
+      Type fieldType = TypeParameterResolver.resolveFieldType(field, type);
+      getTypes.put(field.getName(), typeToClass(fieldType));
     }
   }
 

src/main/java/org/apache/ibatis/reflection/TypeParameterResolver.java

@@ -16,6 +16,7 @@
 package org.apache.ibatis.reflection;
 
 import java.lang.reflect.Array;
+import java.lang.reflect.Field;
 import java.lang.reflect.GenericArrayType;
 import java.lang.reflect.Method;
 import java.lang.reflect.ParameterizedType;
@@ -28,16 +29,30 @@
  */
 public class TypeParameterResolver {
 
+  /**
+   * @return The field type as {@link Type}. If it has type parameters in the declaration,<br>
+   *         they will be resolved to the actual runtime {@link Type}s.
+   */
+  public static Type resolveFieldType(Field field, Type srcType) {
+    Type fieldType = field.getGenericType();
+    Class<?> declaringClass = field.getDeclaringClass();
+    return resolveType(fieldType, srcType, declaringClass);
+  }
+
   /**
    * @return The return type of the method as {@link Type}. If it has type parameters in the declaration,<br>
-   *         they will be resolved to the actual runtime {@link Type}.
+   *         they will be resolved to the actual runtime {@link Type}s.
    */
   public static Type resolveReturnType(Method method, Type srcType) {
     Type returnType = method.getGenericReturnType();
     Class<?> declaringClass = method.getDeclaringClass();
     return resolveType(returnType, srcType, declaringClass);
   }
 
+  /**
+   * @return The parameter types of the method as an array of {@link Type}s. If they have type parameters in the declaration,<br>
+   *         they will be resolved to the actual runtime {@link Type}s.
+   */
   public static Type[] resolveParamTypes(Method method, Type srcType) {
     Type[] paramTypes = method.getGenericParameterTypes();
     Class<?> declaringClass = method.getDeclaringClass();

src/test/java/org/apache/ibatis/reflection/ReflectorTest.java

@@ -99,6 +99,20 @@ public void shouldResolveGetterType() throws Exception {
     assertEquals(String.class, reflector.getGetterType("id"));
   }
 
+  @Test
+  public void shouldResolveSetterTypeFromPrivateField() throws Exception {
+    ReflectorFactory reflectorFactory = new DefaultReflectorFactory();
+    Reflector reflector = reflectorFactory.findForClass(Child.class);
+    assertEquals(String.class, reflector.getSetterType("fld"));
+  }
+
+  @Test
+  public void shouldResolveGetterTypeFromPublicField() throws Exception {
+    ReflectorFactory reflectorFactory = new DefaultReflectorFactory();
+    Reflector reflector = reflectorFactory.findForClass(Child.class);
+    assertEquals(String.class, reflector.getGetterType("pubFld"));
+  }
+
   @Test
   public void shouldResolveParameterizedGetterType() throws Exception {
     ReflectorFactory reflectorFactory = new DefaultReflectorFactory();
@@ -119,6 +133,8 @@ static abstract class Parent<T extends Serializable> {
     protected T id;
     protected List<T> list;
     protected T[] array;
+    private T fld;
+    public T pubFld;
     public T getId() {
       return id;
     }
@@ -137,6 +153,9 @@ public T[] getArray() {
     public void setArray(T[] array) {
       this.array = array;
     }
+    public T getFld() {
+      return fld;
+    }
   }
 
   static class Child extends Parent<String> {

src/test/java/org/apache/ibatis/reflection/TypeParameterResolverTest.java

@@ -17,6 +17,7 @@
 
 import static org.junit.Assert.*;
 
+import java.lang.reflect.Field;
 import java.lang.reflect.GenericArrayType;
 import java.lang.reflect.Method;
 import java.lang.reflect.ParameterizedType;
@@ -361,4 +362,13 @@ public void testReturn_Anonymous() throws Exception {
     Type result = TypeParameterResolver.resolveReturnType(method, clazz);
     assertEquals(Object.class, result);
   }
+
+  @Test
+  public void testField_GenericField() throws Exception {
+    Class<?> clazz = SubCalculator.class;
+    Class<?> declaredClass = Calculator.class;
+    Field field = declaredClass.getDeclaredField("fld");
+    Type result = TypeParameterResolver.resolveFieldType(field, clazz);
+    assertEquals(String.class, result);
+  }
 }

src/test/java/org/apache/ibatis/reflection/typeparam/Calculator.java

@@ -18,6 +18,10 @@
 public class Calculator<T> {
   protected T id;
 
+  private T fld;
+
+  protected T attribute;
+
   public T getId() {
     return id;
   }

src/test/java/org/apache/ibatis/submitted/generictyperesolution/CreateDB.sql

@@ -18,7 +18,9 @@ drop table users if exists;
 
 create table users (
   id int identity,
-  name varchar(20)
+  name varchar(20),
+  fld1 int,
+  fld2 int
 );
 
-insert into users (id, name) values(1, 'User1');
+insert into users (id, name, fld1, fld2) values(1, 'User1', 12, 34);

src/test/java/org/apache/ibatis/submitted/generictyperesolution/Entity.java

@@ -22,6 +22,10 @@ public class Entity<T extends Serializable> {
 
   private String name;
 
+  private T fld1;
+
+  public T fld2;
+
   public T getId() {
     return id;
   }
@@ -37,4 +41,8 @@ public String getName() {
   public void setName(String name) {
     this.name = name;
   }
+
+  public T getFld1() {
+    return fld1;
+  }
 }

src/test/java/org/apache/ibatis/submitted/generictyperesolution/GenericTypeResolutionTest.java

@@ -59,6 +59,7 @@ public void shouldGetAUser() {
       criteria.setId(1);
       User result = mapper.getUser(criteria);
       assertEquals("User1", result.getName());
+      assertEquals(Integer.valueOf(12), result.getFld1());
     } finally {
       sqlSession.close();
     }
@@ -71,6 +72,7 @@ public void shouldInsertAUser() {
       Mapper mapper = sqlSession.getMapper(Mapper.class);
       User user = new User();
       user.setName("User2");
+      user.fld2 =56;
       mapper.insertUser(user);
       User result = mapper.getUserByName("User2");
       assertNotNull(result);

src/test/java/org/apache/ibatis/submitted/generictyperesolution/Mapper.java

@@ -25,6 +25,6 @@ public interface Mapper {
   @Select("select * from users where name = #{name}")
   User getUserByName(String name);
 
-  @Insert("insert into users (name) values (#{name})")
+  @Insert("insert into users (name, fld2) values (#{name}, #{fld2})")
   void insertUser(User user);
 }