optimize TypeParameterResolver

Author: guanchengang

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

@@ -129,9 +129,10 @@ private static Type resolveGenericArrayType(GenericArrayType genericArrayType, T
   private static ParameterizedType resolveParameterizedType(ParameterizedType parameterizedType, Type srcType,
       Class<?> declaringClass) {
     Class<?> rawType = (Class<?>) parameterizedType.getRawType();
+    Type ownerType = parameterizedType.getOwnerType();
     Type[] typeArgs = parameterizedType.getActualTypeArguments();
     Type[] args = resolveTypes(typeArgs, srcType, declaringClass);
-    return new ParameterizedTypeImpl(rawType, null, args);
+    return new ParameterizedTypeImpl(rawType, ownerType, args);
   }
 
   private static Type resolveWildcardType(WildcardType wildcardType, Type srcType, Class<?> declaringClass) {
@@ -158,7 +159,7 @@ private static Type resolveTypeVar(TypeVariable<?> typeVar, Type srcType, Class<
       }
     } else {
       throw new IllegalArgumentException(
-          "The 2nd arg must be Class or ParameterizedType, but was: " + srcType.getClass());
+          "The srcType(2nd arg) must be Class or ParameterizedType, but was: " + srcType.getClass());
     }
 
     if (clazz == declaringClass) {
@@ -198,7 +199,7 @@ private static Type scanSuperTypes(TypeVariable<?> typeVar, Type srcType, Class<
         for (int i = 0; i < parentTypeVars.length; i++) {
           if (typeVar.equals(parentTypeVars[i])) {
             Type actualType = parentAsType.getActualTypeArguments()[i];
-            return actualType instanceof TypeVariable<?> ? Object.class : actualType;
+            return actualType instanceof TypeVariable<?> ? ((TypeVariable<?>) actualType).getBounds()[0] : actualType;
           }
         }
       }
@@ -230,7 +231,40 @@ private static ParameterizedType translateParentTypeVars(ParameterizedType srcTy
         newParentArgs[i] = parentTypeArgs[i];
       }
     }
-    return noChange ? parentType : new ParameterizedTypeImpl((Class<?>) parentType.getRawType(), null, newParentArgs);
+    if (noChange && !(parentType instanceof ParameterizedTypeImpl)) noChange = false;
+    return noChange
+      ? parentType
+      : new ParameterizedTypeImpl((Class<?>) parentType.getRawType(), parentType.getOwnerType(), newParentArgs);
+  }
+
+  private static Type canonicalize(Type type) {
+    if (type instanceof ParameterizedType) {
+      ParameterizedType p = (ParameterizedType) type;
+      return new ParameterizedTypeImpl((Class<?>) p.getRawType(), p.getOwnerType(), p.getActualTypeArguments());
+    }
+    else if (type instanceof GenericArrayType) {
+      GenericArrayType g = (GenericArrayType) type;
+      return new GenericArrayTypeImpl(g.getGenericComponentType());
+    }
+    else if (type instanceof WildcardType) {
+      WildcardType w = (WildcardType) type;
+      return new WildcardTypeImpl(w.getLowerBounds(), w.getUpperBounds());
+    }
+    else {
+      return type;
+    }
+  }
+
+  private static Type[] canonicalizeTypes(Type[] types) {
+    if (types == null || types.length == 0) {
+      return new Type[0];
+    }
+    int length = types.length;
+    Type[] canonicalizedTypes = new Type[length];
+    for (int i = 0; i < length; i++) {
+      canonicalizedTypes[i] = canonicalize(types[i]);
+    }
+    return canonicalizedTypes;
   }
 
   private TypeParameterResolver() {
@@ -244,11 +278,11 @@ static class ParameterizedTypeImpl implements ParameterizedType {
 
     private final Type[] actualTypeArguments;
 
-    public ParameterizedTypeImpl(Class<?> rawType, Type ownerType, Type[] actualTypeArguments) {
+    ParameterizedTypeImpl(Class<?> rawType, Type ownerType, Type[] actualTypeArguments) {
       super();
-      this.rawType = rawType;
-      this.ownerType = ownerType;
-      this.actualTypeArguments = actualTypeArguments;
+      this.rawType = (Class<?>) canonicalize(rawType);
+      this.ownerType = canonicalize(ownerType);
+      this.actualTypeArguments = canonicalizeTypes(actualTypeArguments);
     }
 
     @Override
@@ -283,7 +317,21 @@ public boolean equals(Object obj) {
 
     @Override
     public String toString() {
-      StringBuilder s = new StringBuilder().append(rawType.getName()).append("<");
+      StringBuilder s = new StringBuilder();
+      if (ownerType != null) {
+        s.append(ownerType.getTypeName()).append("$");
+        if (ownerType instanceof ParameterizedTypeImpl) {
+          // remove prefixes that do not contain generic information
+          s.append(
+            rawType.getName().replace(((ParameterizedTypeImpl) ownerType).rawType.getName() + "$", ""));
+        }
+        else {
+          s.append(rawType.getSimpleName());
+        }
+      } else {
+        s.append(rawType.getName());
+      }
+      s.append("<");
       for (int i = 0; i < actualTypeArguments.length; i++) {
         if (i > 0) {
           s.append(", ");
@@ -301,8 +349,8 @@ static class WildcardTypeImpl implements WildcardType {
 
     WildcardTypeImpl(Type[] lowerBounds, Type[] upperBounds) {
       super();
-      this.lowerBounds = lowerBounds;
-      this.upperBounds = upperBounds;
+      this.lowerBounds = canonicalizeTypes(lowerBounds);
+      this.upperBounds = canonicalizeTypes(upperBounds);
     }
 
     @Override
@@ -353,7 +401,7 @@ static class GenericArrayTypeImpl implements GenericArrayType {
 
     GenericArrayTypeImpl(Type genericComponentType) {
       super();
-      this.genericComponentType = genericComponentType;
+      this.genericComponentType = canonicalize(genericComponentType);
     }
 
     @Override
@@ -380,7 +428,7 @@ public boolean equals(Object obj) {
 
     @Override
     public String toString() {
-      return new StringBuilder().append(genericComponentType.toString()).append("[]").toString();
+      return new StringBuilder().append(genericComponentType.getTypeName()).append("[]").toString();
     }
   }
 }

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

@@ -18,6 +18,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.io.Serializable;
 import java.lang.reflect.Field;
 import java.lang.reflect.GenericArrayType;
 import java.lang.reflect.Method;
@@ -230,7 +231,6 @@ void returnLv2ArrayOfArray() throws Exception {
     Type result = TypeParameterResolver.resolveReturnType(method, clazz);
     assertTrue(result instanceof Class);
     Class<?> resultClass = (Class<?>) result;
-    assertTrue(result instanceof Class);
     assertTrue(resultClass.isArray());
     assertTrue(resultClass.getComponentType().isArray());
     assertEquals(String.class, resultClass.getComponentType().getComponentType());
@@ -513,6 +513,41 @@ void shouldResolveInterfaceTypeParamsDeeper() {
     assertEquals(String.class, types[0]);
   }
 
+  @Test
+  void shouldResolveWildcardTypeInClassDefinition() throws Exception {
+    class A<T extends Serializable> {
+      public T foo(T t) {
+        return t;
+      }
+    }
+
+    class B<T extends Number> extends A<T> {
+
+    }
+
+    class C1<T extends Integer> extends B<T> {
+
+    }
+
+    class C2 extends B<Integer> {
+
+    }
+
+    class C3 extends B {
+
+    }
+
+    Method m = A.class.getMethod("foo", Serializable.class);
+
+    assertEquals(Integer.class, TypeParameterResolver.resolveReturnType(m, C1.class));
+    assertEquals(Integer.class, TypeParameterResolver.resolveReturnType(m, C2.class));
+    assertEquals(Number.class, TypeParameterResolver.resolveReturnType(m, C3.class));
+
+    assertEquals(Integer.class, TypeParameterResolver.resolveParamTypes(m, C1.class)[0]);
+    assertEquals(Integer.class, TypeParameterResolver.resolveParamTypes(m, C2.class)[0]);
+    assertEquals(Number.class, TypeParameterResolver.resolveParamTypes(m, C3.class)[0]);
+  }
+
   class AA {
   }