net.optionfactory.hj.jackson.reflection.ReflectionUtils Maven / Gradle / Ivy
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package net.optionfactory.hj.jackson.reflection;
/*
* Copyright 2002-2016 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
*
* http://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.
*/
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.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
/**
* Simple utility class for working with the reflection API and handling
* reflection exceptions.
*
* Only intended for internal use.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @author Rod Johnson
* @author Costin Leau
* @author Sam Brannen
* @author Chris Beams
* @since 1.2.2
*/
public abstract class ReflectionUtils {
private static final Method[] NO_METHODS = {};
private static final Field[] NO_FIELDS = {};
/**
* Cache for {@link Class#getDeclaredMethods()} plus equivalent default methods
* from Java 8 based interfaces, allowing for fast iteration.
*/
private static final Map, Method[]> declaredMethodsCache =
new ConcurrentReferenceHashMap, Method[]>(256);
/**
* Cache for {@link Class#getDeclaredFields()}, allowing for fast iteration.
*/
private static final Map, Field[]> declaredFieldsCache =
new ConcurrentReferenceHashMap, Field[]>(256);
/**
* 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]);
}
/**
* Attempt to find a {@link Method} on the supplied class with the supplied name
* and parameter types. 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
* @param paramTypes the parameter types of the method
* (may be {@code null} to indicate any signature)
* @return the Method object, or {@code null} if none found
*/
public static Method findMethod(Class clazz, String name, Class... paramTypes) {
Assert.notNull(clazz, "Class must not be null");
Assert.notNull(name, "Method name must not be null");
Class searchType = clazz;
while (searchType != null) {
Method[] methods = (searchType.isInterface() ? searchType.getMethods() : getDeclaredMethods(searchType));
for (Method method : methods) {
if (name.equals(method.getName()) &&
(paramTypes == null || Arrays.equals(paramTypes, method.getParameterTypes()))) {
return method;
}
}
searchType = searchType.getSuperclass();
}
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(java.lang.reflect.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);
}
/**
* This variant retrieves {@link Class#getDeclaredMethods()} from a local cache
* in order to avoid the JVM's SecurityManager check and defensive array copying.
* In addition, it also includes Java 8 default methods from locally implemented
* interfaces, since those are effectively to be treated just like declared methods.
* @param clazz the class to introspect
* @return the cached array of methods
* @see Class#getDeclaredMethods()
*/
private static Method[] getDeclaredMethods(Class clazz) {
Method[] result = declaredMethodsCache.get(clazz);
if (result == null) {
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;
}
declaredMethodsCache.put(clazz, (result.length == 0 ? NO_METHODS : result));
}
return result;
}
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;
}
/**
* Clear the internal method/field cache.
* @since 4.2.4
*/
public static void clearCache() {
declaredMethodsCache.clear();
declaredFieldsCache.clear();
}
/**
* Action to take on each method.
*/
public interface MethodCallback {
/**
* Perform an operation using the given method.
* @param method the method to operate on
*/
void doWith(Method method) throws IllegalArgumentException, IllegalAccessException;
}
/**
* Callback optionally used to filter methods to be operated on by a method callback.
*/
public interface MethodFilter {
/**
* Determine whether the given method matches.
* @param method the method to check
*/
boolean matches(Method method);
}
/**
* Callback interface invoked on each field in the hierarchy.
*/
public interface FieldCallback {
/**
* Perform an operation using the given field.
* @param field the field to operate on
*/
void doWith(Field field) throws IllegalArgumentException, IllegalAccessException;
}
/**
* Callback optionally used to filter fields to be operated on by a field callback.
*/
public interface FieldFilter {
/**
* Determine whether the given field matches.
* @param field the field to check
*/
boolean matches(Field field);
}
/**
* Pre-built FieldFilter that matches all non-static, non-final fields.
*/
public static final FieldFilter COPYABLE_FIELDS = new FieldFilter() {
@Override
public boolean matches(Field field) {
return !(Modifier.isStatic(field.getModifiers()) || Modifier.isFinal(field.getModifiers()));
}
};
/**
* Pre-built MethodFilter that matches all non-bridge methods.
*/
public static final MethodFilter NON_BRIDGED_METHODS = new MethodFilter() {
@Override
public boolean matches(Method method) {
return !method.isBridge();
}
};
/**
* Pre-built MethodFilter that matches all non-bridge methods
* which are not declared on {@code java.lang.Object}.
*/
public static final MethodFilter USER_DECLARED_METHODS = new MethodFilter() {
@Override
public boolean matches(Method method) {
return (!method.isBridge() && method.getDeclaringClass() != Object.class);
}
};
}