org.springframework.util.ReflectionUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2008 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.
*/
package org.springframework.util;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.sql.SQLException;
import java.util.Arrays;
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.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @author Rod Johnson
* @author Costin Leau
* @since 1.2.2
*/
public abstract class ReflectionUtils {
/**
* Attempt to find a {@link Method} on the supplied class with the supplied name
* and no parameters. Searches all superclasses up to Object.
*
Returns 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 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 Object.
*
Returns 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
* @return the Method object, or 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 (!Object.class.equals(searchType) && searchType != null) {
Method[] methods = (searchType.isInterface() ? searchType.getMethods() : searchType.getDeclaredMethods());
for (int i = 0; i < methods.length; i++) {
Method method = methods[i];
if (name.equals(method.getName()) && 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 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, null);
}
/**
* Invoke the specified {@link Method} against the supplied target object
* with the supplied arguments. The target object can be 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 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");
}
/**
* Invoke the specified JDBC API {@link Method} against the supplied
* target object with no arguments.
* @param method the method to invoke
* @param target the target object to invoke the method on
* @return the invocation result, if any
* @throws SQLException the JDBC API SQLException to rethrow (if any)
* @see #invokeJdbcMethod(java.lang.reflect.Method, Object, Object[])
*/
public static Object invokeJdbcMethod(Method method, Object target) throws SQLException {
return invokeJdbcMethod(method, target, null);
}
/**
* Invoke the specified JDBC API {@link Method} against the supplied
* target object with the supplied arguments.
* @param method the method to invoke
* @param target the target object to invoke the method on
* @param args the invocation arguments (may be null)
* @return the invocation result, if any
* @throws SQLException the JDBC API SQLException to rethrow (if any)
* @see #invokeMethod(java.lang.reflect.Method, Object, Object[])
*/
public static Object invokeJdbcMethod(Method method, Object target, Object[] args) throws SQLException {
try {
return method.invoke(target, args);
}
catch (IllegalAccessException ex) {
handleReflectionException(ex);
}
catch (InvocationTargetException ex) {
if (ex.getTargetException() instanceof SQLException) {
throw (SQLException) ex.getTargetException();
}
handleInvocationTargetException(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 else.
* @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);
}
throw new IllegalStateException(
"Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
}
/**
* 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 IllegalStateException else.
* @param ex the invocation target exception to handle
*/
public static void handleInvocationTargetException(InvocationTargetException ex) {
if (ex.getTargetException() instanceof RuntimeException) {
throw (RuntimeException) ex.getTargetException();
}
if (ex.getTargetException() instanceof Error) {
throw (Error) ex.getTargetException();
}
throw new IllegalStateException(
"Unexpected exception thrown by method - " + ex.getTargetException().getClass().getName() +
": " + ex.getTargetException().getMessage());
}
/**
* Determine whether the given method explicitly declares the given exception
* or one of its superclasses, which means that an exception of that type
* can be propagated as-is within a reflective invocation.
* @param method the declaring method
* @param exceptionType the exception to throw
* @return true if the exception can be thrown as-is;
* false if it needs to be wrapped
*/
public static boolean declaresException(Method method, Class exceptionType) {
Assert.notNull(method, "Method must not be null");
Class[] declaredExceptions = method.getExceptionTypes();
for (int i = 0; i < declaredExceptions.length; i++) {
Class declaredException = declaredExceptions[i];
if (declaredException.isAssignableFrom(exceptionType)) {
return true;
}
}
return false;
}
/**
* Determine whether the given field is a "public static final" constant.
* @param field the field to check
*/
public static boolean isPublicStaticFinal(Field field) {
int modifiers = field.getModifiers();
return (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers));
}
/**
* Make the given field accessible, explicitly setting it accessible if necessary.
* The setAccessible(true) method is only called when actually necessary,
* to avoid unnecessary conflicts with a JVM SecurityManager (if active).
* @param field the field to make accessible
* @see java.lang.reflect.Field#setAccessible
*/
public static void makeAccessible(Field field) {
if (!Modifier.isPublic(field.getModifiers()) ||
!Modifier.isPublic(field.getDeclaringClass().getModifiers())) {
field.setAccessible(true);
}
}
/**
* Perform the given callback operation on all matching methods of the
* given class and superclasses.
*
The same named method occurring on subclass and superclass will
* appear twice, unless excluded by a {@link MethodFilter}.
* @param targetClass class to start looking at
* @param mc the callback to invoke for each method
* @see #doWithMethods(Class, MethodCallback, MethodFilter)
*/
public static void doWithMethods(Class targetClass, MethodCallback mc) throws IllegalArgumentException {
doWithMethods(targetClass, mc, null);
}
/**
* Perform the given callback operation on all matching methods of the
* given class and superclasses.
*
The same named method occurring on subclass and superclass will
* appear twice, unless excluded by the specified {@link MethodFilter}.
* @param targetClass class to start looking at
* @param mc the callback to invoke for each method
* @param mf the filter that determines the methods to apply the callback to
*/
public static void doWithMethods(Class targetClass, MethodCallback mc, MethodFilter mf)
throws IllegalArgumentException {
// Keep backing up the inheritance hierarchy.
do {
Method[] methods = targetClass.getDeclaredMethods();
for (int i = 0; i < methods.length; i++) {
if (mf != null && !mf.matches(methods[i])) {
continue;
}
try {
mc.doWith(methods[i]);
}
catch (IllegalAccessException ex) {
throw new IllegalStateException(
"Shouldn't be illegal to access method '" + methods[i].getName() + "': " + ex);
}
}
targetClass = targetClass.getSuperclass();
}
while (targetClass != null);
}
/**
* Get all declared methods on the leaf class and all superclasses.
* Leaf class methods are included first.
*/
public static Method[] getAllDeclaredMethods(Class leafClass) throws IllegalArgumentException {
final List list = new LinkedList();
doWithMethods(leafClass, new MethodCallback() {
public void doWith(Method m) {
list.add(m);
}
});
return (Method[]) list.toArray(new Method[list.size()]);
}
/**
* Invoke the given callback on all fields in the target class,
* going up the class hierarchy to get all declared fields.
* @param targetClass the target class to analyze
* @param fc the callback to invoke for each field
*/
public static void doWithFields(Class targetClass, FieldCallback fc) throws IllegalArgumentException {
doWithFields(targetClass, fc, null);
}
/**
* Invoke the given callback on all fields in the target class,
* going up the class hierarchy to get all declared fields.
* @param targetClass the target class to analyze
* @param fc the callback to invoke for each field
* @param ff the filter that determines the fields to apply the callback to
*/
public static void doWithFields(Class targetClass, FieldCallback fc, FieldFilter ff)
throws IllegalArgumentException {
// Keep backing up the inheritance hierarchy.
do {
// Copy each field declared on this class unless it's static or file.
Field[] fields = targetClass.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
// Skip static and final fields.
if (ff != null && !ff.matches(fields[i])) {
continue;
}
try {
fc.doWith(fields[i]);
}
catch (IllegalAccessException ex) {
throw new IllegalStateException(
"Shouldn't be illegal to access field '" + fields[i].getName() + "': " + ex);
}
}
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
}
/**
* Given the source object and the destination, which must be the same class
* or a subclass, copy all fields, including inherited fields. Designed to
* work on objects with public no-arg constructors.
* @throws IllegalArgumentException if the arguments are incompatible
*/
public static void shallowCopyFieldState(final Object src, final Object dest) throws IllegalArgumentException {
if (src == null) {
throw new IllegalArgumentException("Source for field copy cannot be null");
}
if (dest == null) {
throw new IllegalArgumentException("Destination for field copy cannot be null");
}
if (!src.getClass().isAssignableFrom(dest.getClass())) {
throw new IllegalArgumentException("Destination class [" + dest.getClass().getName() +
"] must be same or subclass as source class [" + src.getClass().getName() + "]");
}
doWithFields(src.getClass(), new ReflectionUtils.FieldCallback() {
public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {
makeAccessible(field);
Object srcValue = field.get(src);
field.set(dest, srcValue);
}
}, ReflectionUtils.COPYABLE_FIELDS);
}
/**
* Action to take on each method.
*/
public static 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 method fields to be operated on by a method callback.
*/
public static 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 static 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 static 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 FieldFilter COPYABLE_FIELDS = new FieldFilter() {
public boolean matches(Field field) {
return !(Modifier.isStatic(field.getModifiers()) ||
Modifier.isFinal(field.getModifiers()));
}
};
}