Only intended for internal use.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @author Rod Johnson
* @author Costin Leau
* @author Sam Brannen
* @since 1.2.2
*/
public abstract class ReflectionUtils {
/**
* Attempt to find a {@link Field field} on the supplied {@link Class} with
* the supplied name. Searches all superclasses up to {@link Object}.
* @param clazz the class to introspect
* @param name the name of the field
* @return the corresponding Field object, or null if not found
*/
public static Field findField(Class clazz, String name) {
return findField(clazz, name, null);
}
/**
* Attempt to find a {@link Field field} on the supplied {@link Class} with
* the supplied name and/or {@link Class type}. Searches all
* superclasses up to {@link Object}.
* @param clazz the class to introspect
* @param name the name of the field (may be null if type is specified)
* @param type the type of the field (may be null if name is specified)
* @return the corresponding Field object, or null if not found
*/
public static Field findField(Class clazz, String name, Class type) {
Assert.notNull(clazz, "Class must not be null");
Assert.isTrue(name != null || type != null, "Either name or type of the field must be specified");
Class searchType = clazz;
while (!Object.class.equals(searchType) && searchType != null) {
Field[] fields = searchType.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
if ((name == null || name.equals(field.getName()))
&& (type == null || type.equals(field.getType()))) {
return field;
}
}
searchType = searchType.getSuperclass();
}
return null;
}
/**
* Set the field represented by the supplied {@link Field field object} on
* the specified {@link Object target object} to the specified
* value. In accordance with
* {@link Field#set(Object, Object)} semantics, the new value is
* automatically unwrapped if the underlying field has a primitive type.
*
Thrown exceptions are handled via a call to
* {@link #handleReflectionException(Exception)}.
* @param field the field to set
* @param target the target object on which to set the field
* @param value the value to set; may be null
*/
public static void setField(Field field, Object target, Object value) {
try {
field.set(target, value);
}
catch (IllegalAccessException ex) {
handleReflectionException(ex);
throw new IllegalStateException(
"Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
}
}
/**
* Get the field represented by the supplied {@link Field field object} on
* the specified {@link Object target object}. In accordance with
* {@link Field#get(Object)} semantics, the returned value is
* automatically wrapped if the underlying field has a primitive type.
*
Thrown exceptions are handled via a call to
* {@link #handleReflectionException(Exception)}.
* @param field the field to get
* @param target the target object from which to get the field
* @return the field's current value
*/
public static Object getField(Field field, Object target) {
try {
return field.get(target);
}
catch (IllegalAccessException ex) {
handleReflectionException(ex);
throw new IllegalStateException(
"Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
}
}
/**
* 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
* (may be null to indicate any signature)
* @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()) &&
(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 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); } if (ex instanceof RuntimeException) { throw (RuntimeException) ex; } handleUnexpectedException(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 IllegalStateException else. * @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 an {@link RuntimeException} * or {@link Error} if appropriate; otherwise, throws an * {@link IllegalStateException}. * @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; } handleUnexpectedException(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 IllegalStateException}.
* @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;
}
handleUnexpectedException(ex);
}
/**
* Throws an IllegalStateException with the given exception as root cause.
* @param ex the unexpected exception
*/
private static void handleUnexpectedException(Throwable ex) {
// Needs to avoid the chained constructor for JDK 1.4 compatibility.
IllegalStateException isex = new IllegalStateException("Unexpected exception thrown");
isex.initCause(ex);
throw isex;
}
/**
* 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));
}
/**
* Determine whether the given method is an "equals" method.
* @see java.lang.Object#equals
*/
public static boolean isEqualsMethod(Method method) {
if (method == null || !method.getName().equals("equals")) {
return false;
}
Class[] paramTypes = method.getParameterTypes();
return (paramTypes.length == 1 && paramTypes[0] == Object.class);
}
/**
* Determine whether the given method is a "hashCode" method.
* @see java.lang.Object#hashCode
*/
public static boolean isHashCodeMethod(Method method) {
return (method != null && method.getName().equals("hashCode") &&
method.getParameterTypes().length == 0);
}
/**
* Determine whether the given method is a "toString" method.
* @see java.lang.Object#toString()
*/
public static boolean isToStringMethod(Method method) {
return (method != null && method.getName().equals("toString") &&
method.getParameterTypes().length == 0);
}
/**
* 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);
}
}
/**
* Make the given method 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 method the method to make accessible
* @see java.lang.reflect.Method#setAccessible
*/
public static void makeAccessible(Method method) {
if (!Modifier.isPublic(method.getModifiers()) ||
!Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
method.setAccessible(true);
}
}
/**
* Make the given constructor 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 ctor the constructor to make accessible
* @see java.lang.reflect.Constructor#setAccessible
*/
public static void makeAccessible(Constructor ctor) {
if (!Modifier.isPublic(ctor.getModifiers()) ||
!Modifier.isPublic(ctor.getDeclaringClass().getModifiers())) {
ctor.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 ArrayList(32); doWithMethods(leafClass, new MethodCallback() { public void doWith(Method method) { list.add(method); } }); 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 FieldCallback() { public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException { makeAccessible(field); Object srcValue = field.get(src); field.set(dest, srcValue); } }, 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())); } }; }