Polishing.

Add generic signature, skip static initializer if not required, access classes in static initializer through constants instead of using forName(…). See #3365

Author: mp911de

src/main/java/org/springframework/data/mapping/model/ClassGeneratingPropertyAccessorFactory.java

@@ -384,13 +384,22 @@ static Class<?> generateCustomAccessorClass(PersistentEntity<?, ?> entity) {
 static byte[] generateBytecode(String internalClassName, PersistentEntity<?, ?> entity) {
 
 ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
-cw.visit(Opcodes.V1_8, ACC_PUBLIC + ACC_SUPER, internalClassName, null, JAVA_LANG_OBJECT, IMPLEMENTED_INTERFACES);
+
+String signature = referenceName(JAVA_LANG_OBJECT) + String.format("L%s<%s>;",
+Type.getInternalName(PersistentPropertyAccessor.class), referenceName(entity.getType()));
+
+cw.visit(Opcodes.V1_8, ACC_PUBLIC + ACC_SUPER, internalClassName, signature, JAVA_LANG_OBJECT,
+IMPLEMENTED_INTERFACES);
 
 List<PersistentProperty<?>> persistentProperties = getPersistentProperties(entity);
 
 visitFields(entity, persistentProperties, cw);
 visitDefaultConstructor(entity, internalClassName, cw);
-visitStaticInitializer(entity, persistentProperties, internalClassName, cw);
+
+if (requiresMethodHandleSetup(entity, persistentProperties)) {
+visitStaticInitializer(entity, persistentProperties, internalClassName, cw);
+}
+
 visitBeanGetter(entity, internalClassName, cw);
 visitSetProperty(entity, persistentProperties, internalClassName, cw);
 visitGetProperty(entity, persistentProperties, internalClassName, cw);
@@ -515,9 +524,7 @@ private static void visitDefaultConstructor(PersistentEntity<?, ?> entity, Strin
  *	Method getter;
  *	Method setter;
  *	MethodHandles.Lookup lookup = MethodHandles.lookup();
- *	Class class_1 = Class.forName("org.springframework.data.mapping.Person");
- *	Class class_2 = Class.forName("org.springframework.data.mapping.PersonWithId");
- *	Field field = class_2.getDeclaredField("id");
+ *	Field field = org.springframework.data.mapping.PersonWithId.class.getDeclaredField("id");
  *	field.setAccessible(true);
  *	$id_fieldGetter = lookup.unreflectGetter(field);
  *	$id_fieldSetter = lookup.unreflectSetter(field);
@@ -539,37 +546,27 @@ private static void visitStaticInitializer(PersistentEntity<?, ?> entity,
 String.format("()%s", referenceName(JAVA_LANG_INVOKE_METHOD_HANDLES_LOOKUP)), false);
 mv.visitVarInsn(ASTORE, 0);
 
-List<Class<?>> entityClasses = getPropertyDeclaratingClasses(persistentProperties);
-
-for (Class<?> entityClass : entityClasses) {
-
-mv.visitLdcInsn(entityClass.getName());
-mv.visitMethodInsn(INVOKESTATIC, JAVA_LANG_CLASS, "forName",
-String.format("(%s)%s", referenceName(JAVA_LANG_STRING), referenceName(JAVA_LANG_CLASS)), false);
-mv.visitVarInsn(ASTORE, classVariableIndex5(entityClasses, entityClass));
-}
-
 for (PersistentProperty<?> property : persistentProperties) {
 
 if (property.usePropertyAccess()) {
 
 if (generateMethodHandle(entity, property.getGetter())) {
-visitPropertyGetterInitializer(property, mv, entityClasses, internalClassName);
+visitPropertyGetterInitializer(property, mv, internalClassName);
 }
 
 if (generateMethodHandle(entity, property.getSetter())) {
-visitPropertySetterInitializer(property.getSetter(), property, mv, entityClasses, internalClassName,
+visitPropertySetterInitializer(property.getSetter(), property, mv, internalClassName,
 PropertyAccessorClassGenerator::setterName, 2);
 }
 }
 
 if (property.isImmutable() && generateMethodHandle(entity, property.getWither())) {
-visitPropertySetterInitializer(property.getWither(), property, mv, entityClasses, internalClassName,
+visitPropertySetterInitializer(property.getWither(), property, mv, internalClassName,
 PropertyAccessorClassGenerator::witherName, 4);
 }
 
 if (generateSetterMethodHandle(entity, property.getField())) {
-visitFieldGetterSetterInitializer(property, mv, entityClasses, internalClassName);
+visitFieldGetterSetterInitializer(property, mv, internalClassName);
 }
 }
 
@@ -582,14 +579,36 @@ private static void visitStaticInitializer(PersistentEntity<?, ?> entity,
 mv.visitLocalVariable("getter", referenceName(JAVA_LANG_REFLECT_METHOD), null, l0, l1, 3);
 mv.visitLocalVariable("wither", referenceName(JAVA_LANG_REFLECT_METHOD), null, l0, l1, 4);
 
-for (Class<?> entityClass : entityClasses) {
+mv.visitMaxs(0, 0);
+mv.visitEnd();
+}
+
+static boolean requiresMethodHandleSetup(PersistentEntity<?, ?> entity,
+List<PersistentProperty<?>> persistentProperties) {
+
+for (PersistentProperty<?> property : persistentProperties) {
+
+if (property.usePropertyAccess()) {
+
+if (generateMethodHandle(entity, property.getGetter())) {
+return true;
+}
+
+if (generateMethodHandle(entity, property.getSetter())) {
+return true;
+}
+}
+
+if (property.isImmutable() && generateMethodHandle(entity, property.getWither())) {
+return true;
+}
 
-int index = classVariableIndex5(entityClasses, entityClass);
-mv.visitLocalVariable(String.format("class_%d", index), referenceName(JAVA_LANG_CLASS), null, l0, l1, index);
+if (generateSetterMethodHandle(entity, property.getField())) {
+return true;
+}
 }
 
-mv.visitMaxs(0, 0);
-mv.visitEnd();
+return false;
 }
 
 /**
@@ -617,14 +636,14 @@ private static List<Class<?>> getPropertyDeclaratingClasses(List<PersistentPrope
  * Generate property getter initializer.
  */
 private static void visitPropertyGetterInitializer(PersistentProperty<?> property, MethodVisitor mv,
-List<Class<?>> entityClasses, String internalClassName) {
+String internalClassName) {
 
 // getter = <entity>.class.getDeclaredMethod()
 Method getter = property.getGetter();
 
 if (getter != null) {
 
-mv.visitVarInsn(ALOAD, classVariableIndex5(entityClasses, getter.getDeclaringClass()));
+mv.visitLdcInsn(Type.getObjectType(Type.getInternalName(getter.getDeclaringClass())));
 mv.visitLdcInsn(getter.getName());
 mv.visitInsn(ICONST_0);
 mv.visitTypeInsn(ANEWARRAY, JAVA_LANG_CLASS);
@@ -657,14 +676,14 @@ private static void visitPropertyGetterInitializer(PersistentProperty<?> propert
  * Generate property setter/wither initializer.
  */
 private static void visitPropertySetterInitializer(@Nullable Method method, PersistentProperty<?> property,
-MethodVisitor mv, List<Class<?>> entityClasses, String internalClassName,
+MethodVisitor mv, String internalClassName,
 Function<PersistentProperty<?>, String> setterNameFunction, int localVariableIndex) {
 
 // method = <entity>.class.getDeclaredMethod()
 
 if (method != null) {
 
-mv.visitVarInsn(ALOAD, classVariableIndex5(entityClasses, method.getDeclaringClass()));
+mv.visitLdcInsn(Type.getObjectType(Type.getInternalName(method.getDeclaringClass())));
 mv.visitLdcInsn(method.getName());
 
 mv.visitInsn(ICONST_1);
@@ -711,14 +730,14 @@ private static void visitPropertySetterInitializer(@Nullable Method method, Pers
  * Generate field getter and setter initializers.
  */
 private static void visitFieldGetterSetterInitializer(PersistentProperty<?> property, MethodVisitor mv,
-List<Class<?>> entityClasses, String internalClassName) {
+String internalClassName) {
 
 // field = <entity>.class.getDeclaredField()
 
 Field field = property.getField();
 if (field != null) {
 
-mv.visitVarInsn(ALOAD, classVariableIndex5(entityClasses, field.getDeclaringClass()));
+mv.visitLdcInsn(Type.getObjectType(Type.getInternalName(field.getDeclaringClass())));
 mv.visitLdcInsn(field.getName());
 mv.visitMethodInsn(INVOKEVIRTUAL, JAVA_LANG_CLASS, "getDeclaredField",
 String.format("(%s)%s", referenceName(JAVA_LANG_STRING), referenceName(JAVA_LANG_REFLECT_FIELD)), false);