org.springframework.data.util.ReflectionUtils Maven / Gradle / Ivy
/*
* Copyright 2012-2023 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.util;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import org.springframework.beans.BeanUtils;
import org.springframework.core.KotlinDetector;
import org.springframework.core.MethodParameter;
import org.springframework.core.ResolvableType;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils.FieldFilter;
/**
* Spring Data specific reflection utility methods and classes.
*
* @author Oliver Gierke
* @author Thomas Darimont
* @author Christoph Strobl
* @author Mark Paluch
* @author Johannes Englmeier
* @since 1.5
*/
public final class ReflectionUtils {
private ReflectionUtils() {
throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
}
/**
* Creates an instance of the class with the given fully qualified name or returns the given default instance if the
* class cannot be loaded or instantiated.
*
* @param classname the fully qualified class name to create an instance for.
* @param defaultInstance the instance to fall back to in case the given class cannot be loaded or instantiated.
* @return
*/
@SuppressWarnings("unchecked")
public static T createInstanceIfPresent(String classname, T defaultInstance) {
try {
Class type = ClassUtils.forName(classname, ClassUtils.getDefaultClassLoader());
return (T) BeanUtils.instantiateClass(type);
} catch (Exception e) {
return defaultInstance;
}
}
/**
* Check whether the given {@code type} represents a void type such as {@code void}, {@link Void} or Kotlin
* {@code Unit}.
*
* @param type must not be {@literal null}.
* @return whether the given the type is a void type.
* @since 2.4
*/
public static boolean isVoid(Class type) {
if (type == Void.class || Void.TYPE == type) {
return true;
}
if (type.getName().equals("kotlin.Unit")) {
return true;
}
return false;
}
/**
* A {@link FieldFilter} that has a description.
*
* @author Oliver Gierke
*/
public interface DescribedFieldFilter extends FieldFilter {
/**
* Returns the description of the field filter. Used in exceptions being thrown in case uniqueness shall be enforced
* on the field filter.
*
* @return
*/
String getDescription();
}
/**
* A {@link FieldFilter} for a given annotation.
*
* @author Oliver Gierke
*/
public static class AnnotationFieldFilter implements DescribedFieldFilter {
private final Class annotationType;
public AnnotationFieldFilter(Class annotationType) {
this.annotationType = annotationType;
}
public boolean matches(Field field) {
return AnnotationUtils.getAnnotation(field, annotationType) != null;
}
public String getDescription() {
return String.format("Annotation filter for %s", annotationType.getName());
}
}
/**
* Finds the first field on the given class matching the given {@link FieldFilter}.
*
* @param type must not be {@literal null}.
* @param filter must not be {@literal null}.
* @return the field matching the filter or {@literal null} in case no field could be found.
*/
@Nullable
public static Field findField(Class type, FieldFilter filter) {
return findField(type, new DescribedFieldFilter() {
public boolean matches(Field field) {
return filter.matches(field);
}
public String getDescription() {
return String.format("FieldFilter %s", filter.toString());
}
}, false);
}
/**
* Finds the field matching the given {@link DescribedFieldFilter}. Will make sure there's only one field matching the
* filter.
*
* @see #findField(Class, DescribedFieldFilter, boolean)
* @param type must not be {@literal null}.
* @param filter must not be {@literal null}.
* @return the field matching the given {@link DescribedFieldFilter} or {@literal null} if none found.
* @throws IllegalStateException in case more than one matching field is found
*/
@Nullable
public static Field findField(Class type, DescribedFieldFilter filter) {
return findField(type, filter, true);
}
/**
* Finds the field matching the given {@link DescribedFieldFilter}. Will make sure there's only one field matching the
* filter in case {@code enforceUniqueness} is {@literal true}.
*
* @param type must not be {@literal null}.
* @param filter must not be {@literal null}.
* @param enforceUniqueness whether to enforce uniqueness of the field
* @return the field matching the given {@link DescribedFieldFilter} or {@literal null} if none found.
* @throws IllegalStateException if enforceUniqueness is true and more than one matching field is found
*/
@Nullable
public static Field findField(Class type, DescribedFieldFilter filter, boolean enforceUniqueness) {
Assert.notNull(type, "Type must not be null");
Assert.notNull(filter, "Filter must not be null");
Class targetClass = type;
Field foundField = null;
while (targetClass != Object.class) {
for (Field field : targetClass.getDeclaredFields()) {
if (!filter.matches(field)) {
continue;
}
if (!enforceUniqueness) {
return field;
}
if (foundField != null && enforceUniqueness) {
throw new IllegalStateException(filter.getDescription());
}
foundField = field;
}
targetClass = targetClass.getSuperclass();
}
return foundField;
}
/**
* Finds the field of the given name on the given type.
*
* @param type must not be {@literal null}.
* @param name must not be {@literal null} or empty.
* @return
* @throws IllegalArgumentException in case the field can't be found.
*/
public static Field findRequiredField(Class type, String name) {
Field result = org.springframework.util.ReflectionUtils.findField(type, name);
if (result == null) {
throw new IllegalArgumentException(String.format("Unable to find field %s on %s", name, type));
}
return result;
}
/**
* Sets the given field on the given object to the given value. Will make sure the given field is accessible.
*
* @param field must not be {@literal null}.
* @param target must not be {@literal null}.
* @param value
*/
public static void setField(Field field, Object target, @Nullable Object value) {
org.springframework.util.ReflectionUtils.makeAccessible(field);
org.springframework.util.ReflectionUtils.setField(field, target, value);
}
/**
* Finds a constructor on the given type that matches the given constructor arguments.
*
* @param type must not be {@literal null}.
* @param constructorArguments must not be {@literal null}.
* @return a {@link Constructor} that is compatible with the given arguments.
*/
public static Optional> findConstructor(Class type, Object... constructorArguments) {
Assert.notNull(type, "Target type must not be null");
Assert.notNull(constructorArguments, "Constructor arguments must not be null");
return Arrays.stream(type.getDeclaredConstructors())//
.filter(constructor -> argumentsMatch(constructor.getParameterTypes(), constructorArguments))//
.findFirst();
}
/**
* Returns the method with the given name of the given class and parameter types. Prefers regular methods over
* {@link Method#isBridge() bridge} and {@link Method#isSynthetic() synthetic} ones.
*
* @param type must not be {@literal null}.
* @param name must not be {@literal null}.
* @param parameterTypes must not be {@literal null}.
* @return the method object.
* @throws IllegalArgumentException in case the method cannot be resolved.
*/
public static Method findRequiredMethod(Class type, String name, Class... parameterTypes) {
Assert.notNull(type, "Class must not be null");
Assert.notNull(name, "Method name must not be null");
Method result = null;
Class searchType = type;
while (searchType != null) {
Method[] methods = (searchType.isInterface() ? searchType.getMethods()
: org.springframework.util.ReflectionUtils.getDeclaredMethods(searchType));
for (Method method : methods) {
if (name.equals(method.getName()) && hasSameParams(method, parameterTypes)) {
if (result == null || result.isSynthetic() || result.isBridge()) {
result = method;
}
}
}
searchType = searchType.getSuperclass();
}
if (result == null) {
String parameterTypeNames = Arrays.stream(parameterTypes) //
.map(Object::toString) //
.collect(Collectors.joining(", "));
throw new IllegalArgumentException(
String.format("Unable to find method %s(%s) on %s", name, parameterTypeNames, type));
}
return result;
}
private static boolean hasSameParams(Method method, Class[] paramTypes) {
return (paramTypes.length == method.getParameterCount() && Arrays.equals(paramTypes, method.getParameterTypes()));
}
/**
* Returns a {@link Stream} of the return and parameters types of the given {@link Method}.
*
* @param method must not be {@literal null}.
* @return
* @since 2.0
*/
public static Stream> returnTypeAndParameters(Method method) {
Assert.notNull(method, "Method must not be null");
Stream> returnType = Stream.of(method.getReturnType());
Stream> parameterTypes = Arrays.stream(method.getParameterTypes());
return Stream.concat(returnType, parameterTypes);
}
/**
* Returns the {@link Method} with the given name and parameters declared on the given type, if available.
*
* @param type must not be {@literal null}.
* @param name must not be {@literal null} or empty.
* @param parameterTypes must not be {@literal null}.
* @return
* @since 2.0
*/
public static Optional getMethod(Class type, String name, ResolvableType... parameterTypes) {
Assert.notNull(type, "Type must not be null");
Assert.hasText(name, "Name must not be null or empty");
Assert.notNull(parameterTypes, "Parameter types must not be null");
List> collect = Arrays.stream(parameterTypes)//
.map(ResolvableType::getRawClass)//
.collect(Collectors.toList());
Method method = org.springframework.util.ReflectionUtils.findMethod(type, name,
collect.toArray(new Class[collect.size()]));
return Optional.ofNullable(method)//
.filter(it -> IntStream.range(0, it.getParameterCount())//
.allMatch(index -> ResolvableType.forMethodParameter(it, index).equals(parameterTypes[index])));
}
private static boolean argumentsMatch(Class[] parameterTypes, Object[] arguments) {
if (parameterTypes.length != arguments.length) {
return false;
}
int index = 0;
for (Class argumentType : parameterTypes) {
Object argument = arguments[index];
// Reject nulls for primitives
if (argumentType.isPrimitive() && argument == null) {
return false;
}
// Type check if argument is not null
if (argument != null && !ClassUtils.isAssignableValue(argumentType, argument)) {
return false;
}
index++;
}
return true;
}
/**
* Returns {@literal} whether the given {@link MethodParameter} is nullable. Nullable parameters are reference types
* and ones that are defined in Kotlin as such.
*
* @return {@literal true} if {@link MethodParameter} is nullable.
* @since 2.0
*/
public static boolean isNullable(MethodParameter parameter) {
if (isVoid(parameter.getParameterType())) {
return true;
}
if (KotlinDetector.isKotlinPresent()
&& KotlinReflectionUtils.isSupportedKotlinClass(parameter.getDeclaringClass())) {
return KotlinReflectionUtils.isNullable(parameter);
}
return !parameter.getParameterType().isPrimitive();
}
/**
* Get default value for a primitive type.
*
* @param type must not be {@literal null}.
* @return boxed primitive default value.
* @since 2.1
*/
public static Object getPrimitiveDefault(Class type) {
if (type == Byte.TYPE || type == Byte.class) {
return (byte) 0;
}
if (type == Short.TYPE || type == Short.class) {
return (short) 0;
}
if (type == Integer.TYPE || type == Integer.class) {
return 0;
}
if (type == Long.TYPE || type == Long.class) {
return 0L;
}
if (type == Float.TYPE || type == Float.class) {
return 0F;
}
if (type == Double.TYPE || type == Double.class) {
return 0D;
}
if (type == Character.TYPE || type == Character.class) {
return '\u0000';
}
if (type == Boolean.TYPE) {
return Boolean.FALSE;
}
throw new IllegalArgumentException(String.format("Primitive type %s not supported", type));
}
/**
* Loads the class with the given name using the given {@link ClassLoader}.
*
* @param name the name of the class to be loaded.
* @param classLoader the {@link ClassLoader} to use to load the class.
* @return the {@link Class} or {@literal null} in case the class can't be loaded for any reason.
* @since 2.5
*/
@Nullable
public static Class loadIfPresent(String name, ClassLoader classLoader) {
try {
return ClassUtils.forName(name, classLoader);
} catch (Exception o_O) {
return null;
}
}
}
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