io.pipelite.expression.support.ReflectionUtils Maven / Gradle / Ivy
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/*
* Copyright (C) 2023-2024 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 io.pipelite.expression.support;
import io.pipelite.common.support.Preconditions;
import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.LinkedList;
import java.util.List;
/**
* Simple utility class for working with the reflection API and handling reflection exceptions.
*
*
* Only intended for internal use.
*
*/
public class ReflectionUtils {
private static final String CLASS_NOT_BE_NULL = "Class must not be null";
private ReflectionUtils() {
super();
}
public static PropertyDescriptor findProperty(Class clazz, String propertyName) {
try {
return new PropertyDescriptor(propertyName, clazz);
}
catch (IntrospectionException e) {
handleInvocationTargetException(new InvocationTargetException(e));
}
return null;
}
/**
* Attempt to find a {@link Method} on the supplied class with the supplied name and no parameters. Searches all
* superclasses up to {@code Object}. Returns {@code null} if no {@link Method} can be found.
*
* @param clazz the class to introspect
* @param name the name of the method
* @return the Method object, or {@code null} if none found
*/
public static Method findMethod(Class clazz, String name) {
return findMethod(clazz, name, new Class[0]);
}
public static Method findMethod(Class clazz, String name, Class... parameterTypes) {
Preconditions.notNull(clazz, CLASS_NOT_BE_NULL);
Preconditions.notNull(name, "Method name must not be null");
try {
return clazz.getMethod(name, parameterTypes);
}
catch (NoSuchMethodException e) {
handleReflectionException(e);
}
catch (SecurityException e) {
rethrowRuntimeException(e);
}
return null;
}
/**
* Invoke the specified {@link Method} against the supplied target object with no arguments. The target object can
* be {@code null} when invoking a static {@link Method}.
*
* Thrown exceptions are handled via a call to {@link #handleReflectionException}.
*
* @param method the method to invoke
* @param target the target object to invoke the method on
* @return the invocation result, if any
* @see #invokeMethod(Method, Object, Object[])
*/
public static Object invokeMethod(Method method, Object target) {
return invokeMethod(method, target, new Object[0]);
}
/**
* Invoke the specified {@link Method} against the supplied target object with the supplied arguments. The target
* object can be {@code null} when invoking a static {@link Method}.
*
* Thrown exceptions are handled via a call to {@link #handleReflectionException}.
*
* @param method the method to invoke
* @param target the target object to invoke the method on
* @param args the invocation arguments (may be {@code null})
* @return the invocation result, if any
*/
public static Object invokeMethod(Method method, Object target, Object... args) {
try {
return method.invoke(target, args);
}
catch (Exception ex) {
handleReflectionException(ex);
}
throw new IllegalStateException("Should never get here");
}
/**
* Handle the given reflection exception. Should only be called if no checked exception is expected to be thrown by
* the target method.
*
* Throws the underlying RuntimeException or Error in case of an InvocationTargetException with such a root cause.
* Throws an IllegalStateException with an appropriate message or UndeclaredThrowableException otherwise.
*
* @param ex the reflection exception to handle
*/
public static void handleReflectionException(Exception ex) {
if (ex instanceof NoSuchMethodException) {
throw new IllegalStateException("Method not found: " + ex.getMessage());
}
if (ex instanceof IllegalAccessException) {
throw new IllegalStateException("Could not access method: " + ex.getMessage());
}
if (ex instanceof InvocationTargetException) {
handleInvocationTargetException((InvocationTargetException) ex);
}
if (ex instanceof RuntimeException) {
throw (RuntimeException) ex;
}
throw new UndeclaredThrowableException(ex);
}
/**
* Handle the given invocation target exception. Should only be called if no checked exception is expected to be
* thrown by the target method.
*
* Throws the underlying RuntimeException or Error in case of such a root cause. Throws an
* UndeclaredThrowableException otherwise.
*
* @param ex the invocation target exception to handle
*/
public static void handleInvocationTargetException(InvocationTargetException ex) {
rethrowRuntimeException(ex.getTargetException());
}
/**
* Rethrow the given {@link Throwable exception}, which is presumably the target exception of an
* {@link InvocationTargetException}. Should only be called if no checked exception is expected to be thrown by the
* target method.
*
* Rethrows the underlying exception cast to a {@link RuntimeException} or {@link Error} if appropriate; otherwise,
* throws an {@link UndeclaredThrowableException}.
*
* @param ex the exception to rethrow
* @throws RuntimeException the rethrown exception
*/
public static void rethrowRuntimeException(Throwable ex) {
if (ex instanceof RuntimeException) {
throw (RuntimeException) ex;
}
if (ex instanceof Error) {
throw (Error) ex;
}
throw new UndeclaredThrowableException(ex);
}
/**
* Rethrow the given {@link Throwable exception}, which is presumably the target exception of an
* {@link InvocationTargetException}. Should only be called if no checked exception is expected to be thrown by the
* target method.
*
* Rethrows the underlying exception cast to an {@link Exception} or {@link Error} if appropriate; otherwise, throws
* an {@link UndeclaredThrowableException}.
*
* @param ex the exception to rethrow
* @throws Exception the rethrown exception (in case of a checked exception)
*/
public static void rethrowException(Throwable ex) throws Exception {
if (ex instanceof Exception) {
throw (Exception) ex;
}
if (ex instanceof Error) {
throw (Error) ex;
}
throw new UndeclaredThrowableException(ex);
}
private static Field[] getDeclaredFields(Class clazz) {
Preconditions.notNull(clazz, CLASS_NOT_BE_NULL);
try {
return clazz.getDeclaredFields();
}
catch (Exception ex) {
throw new IllegalStateException("Failed to introspect Class [" + clazz.getName() + "] from ClassLoader ["
+ clazz.getClassLoader() + "]", ex);
}
}
public static Method[] getDeclaredMethods(Class clazz) {
Preconditions.notNull(clazz, CLASS_NOT_BE_NULL);
Method[] result = null;
try {
Method[] declaredMethods = clazz.getDeclaredMethods();
List defaultMethods = findConcreteMethodsOnInterfaces(clazz);
if (defaultMethods != null) {
result = new Method[declaredMethods.length + defaultMethods.size()];
System.arraycopy(declaredMethods, 0, result, 0, declaredMethods.length);
int index = declaredMethods.length;
for (Method defaultMethod : defaultMethods) {
result[index] = defaultMethod;
index++;
}
}
else {
result = declaredMethods;
}
}
catch (Exception ex) {
throw new IllegalStateException("Failed to introspect Class [" + clazz.getName() + "] from ClassLoader ["
+ clazz.getClassLoader() + "]", ex);
}
return result;
}
public static Field findField(Class clazz, String fieldName) {
try {
Preconditions.notNull(clazz, CLASS_NOT_BE_NULL);
Preconditions.state(fieldName != null, "Name of the field must be specified");
Class searchType = clazz;
while (Object.class != searchType && searchType != null) {
Field[] fields = getDeclaredFields(searchType);
for (Field field : fields) {
if ((fieldName.equals(field.getName()))) {
return field;
}
}
searchType = searchType.getSuperclass();
}
throw new NoSuchFieldException(
String.format("Cannot find field %s on class %s", fieldName, clazz.getName()));
}
catch (Exception e) {
rethrowRuntimeException(e);
}
return null;
}
public static Class resolveFieldType(Class clazz, String fieldName) {
Field field = findField(clazz, fieldName);
return field.getType();
}
private static List findConcreteMethodsOnInterfaces(Class clazz) {
List result = null;
for (Class ifc : clazz.getInterfaces()) {
for (Method ifcMethod : ifc.getMethods()) {
if (!Modifier.isAbstract(ifcMethod.getModifiers())) {
if (result == null) {
result = new LinkedList();
}
result.add(ifcMethod);
}
}
}
return result;
}
public static Method findGetter(Class clazz, String propertyName) {
try {
return findGetter(findProperty(clazz, propertyName));
}
catch (UndeclaredThrowableException e) {
if (e.getCause() instanceof IntrospectionException) {
return null;
}
else {
throw e;
}
}
}
public static Method findGetter(PropertyDescriptor propertyDescriptor) {
return propertyDescriptor.getReadMethod();
}
public static Method findSetter(Class clazz, String propertyName) {
try {
return findSetter(findProperty(clazz, propertyName));
}
catch (UndeclaredThrowableException e) {
if (e.getCause() instanceof IntrospectionException) {
return null;
}
else {
throw e;
}
}
}
public static Method findSetter(PropertyDescriptor propertyDescriptor) {
return propertyDescriptor.getWriteMethod();
}
}