org.xson.tangyuan.util.ReflectionUtils Maven / Gradle / Ivy
package org.xson.tangyuan.util;
import java.lang.reflect.Constructor;
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.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
public class ReflectionUtils {
/**
* Naming prefix for CGLIB-renamed methods.
*
* @see #isCglibRenamedMethod
*/
private static final String CGLIB_RENAMED_METHOD_PREFIX = "CGLIB$";
/**
* Cache for {@link Class#getDeclaredMethods()}, allowing for fast iteration.
*/
private static final Map, Method[]> declaredMethodsCache = new ConcurrentReferenceHashMap, Method[]>(
256);
/**
* Attempt to find a {@link Field field} on the supplied {@link Class} with the supplied {@code 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 {@code 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 {@code 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 {@code null} if type is specified)
* @param type
* the type of the field (may be {@code null} if name is specified)
* @return the corresponding Field object, or {@code 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 (Field field : fields) {
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 {@code 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 {@code 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 {@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");
}
/**
* 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, new Object[0]);
}
/**
* 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 {@code 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;
}
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 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;
}
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 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;
}
throw new UndeclaredThrowableException(ex);
}
/**
* 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 {@code true} if the exception can be thrown as-is; {@code 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 (Class declaredException : declaredExceptions) {
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(Object)
*/
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);
}
/**
* Determine whether the given method is originally declared by {@link java.lang.Object}.
*/
public static boolean isObjectMethod(Method method) {
if (method == null) {
return false;
}
try {
Object.class.getDeclaredMethod(method.getName(), method.getParameterTypes());
return true;
} catch (Exception ex) {
return false;
}
}
/**
* Determine whether the given method is a CGLIB 'renamed' method, following the pattern "CGLIB$methodName$0".
*
* @param renamedMethod
* the method to check
* @see org.springframework.cglib.proxy.Enhancer#rename
*/
public static boolean isCglibRenamedMethod(Method renamedMethod) {
String name = renamedMethod.getName();
if (name.startsWith(CGLIB_RENAMED_METHOD_PREFIX)) {
int i = name.length() - 1;
while (i >= 0 && Character.isDigit(name.charAt(i))) {
i--;
}
return ((i > CGLIB_RENAMED_METHOD_PREFIX.length()) && (i < name.length() - 1) && (name.charAt(i) == '$'));
}
return false;
}
/**
* Make the given field accessible, explicitly setting it accessible if necessary. The {@code 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()) || Modifier
.isFinal(field.getModifiers())) && !field.isAccessible()) {
field.setAccessible(true);
}
}
/**
* Make the given method accessible, explicitly setting it accessible if necessary. The {@code 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.isAccessible()) {
method.setAccessible(true);
}
}
/**
* Make the given constructor accessible, explicitly setting it accessible if necessary. The
* {@code 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.isAccessible()) {
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 clazz
* the class to introspect
* @param mc
* the callback to invoke for each method
* @see #doWithMethods(Class, MethodCallback, MethodFilter)
*/
public static void doWithMethods(Class clazz, MethodCallback mc) {
doWithMethods(clazz, mc, null);
}
/**
* Perform the given callback operation on all matching methods of the given class and superclasses (or given
* interface and super-interfaces).
*
* The same named method occurring on subclass and superclass will appear twice, unless excluded by the specified
* {@link MethodFilter}.
*
* @param clazz
* the class to introspect
* @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 clazz, MethodCallback mc, MethodFilter mf) {
// Keep backing up the inheritance hierarchy.
Method[] methods = getDeclaredMethods(clazz);
for (Method method : methods) {
if (mf != null && !mf.matches(method)) {
continue;
}
try {
mc.doWith(method);
} catch (IllegalAccessException ex) {
throw new IllegalStateException("Not allowed to access method '" + method.getName() + "': " + ex);
}
}
if (clazz.getSuperclass() != null) {
doWithMethods(clazz.getSuperclass(), mc, mf);
} else if (clazz.isInterface()) {
for (Class superIfc : clazz.getInterfaces()) {
doWithMethods(superIfc, mc, mf);
}
}
}
/**
* Get all declared methods on the leaf class and all superclasses. Leaf class methods are included first.
*
* @param leafClass
* the class to introspect
*/
public static Method[] getAllDeclaredMethods(Class leafClass) {
final List methods = new ArrayList(32);
doWithMethods(leafClass, new MethodCallback() {
@Override
public void doWith(Method method) {
methods.add(method);
}
});
return methods.toArray(new Method[methods.size()]);
}
/**
* Get the unique set of declared methods on the leaf class and all superclasses. Leaf class methods are included
* first and while traversing the superclass hierarchy any methods found with signatures matching a method already
* included are filtered out.
*
* @param leafClass
* the class to introspect
*/
public static Method[] getUniqueDeclaredMethods(Class leafClass) {
final List methods = new ArrayList(32);
doWithMethods(leafClass, new MethodCallback() {
@Override
public void doWith(Method method) {
boolean knownSignature = false;
Method methodBeingOverriddenWithCovariantReturnType = null;
for (Method existingMethod : methods) {
if (method.getName().equals(existingMethod.getName())
&& Arrays.equals(method.getParameterTypes(), existingMethod.getParameterTypes())) {
// Is this a covariant return type situation?
if (existingMethod.getReturnType() != method.getReturnType()
&& existingMethod.getReturnType().isAssignableFrom(method.getReturnType())) {
methodBeingOverriddenWithCovariantReturnType = existingMethod;
} else {
knownSignature = true;
}
break;
}
}
if (methodBeingOverriddenWithCovariantReturnType != null) {
methods.remove(methodBeingOverriddenWithCovariantReturnType);
}
if (!knownSignature && !isCglibRenamedMethod(method)) {
methods.add(method);
}
}
});
return methods.toArray(new Method[methods.size()]);
}
/**
* This variant retrieves {@link Class#getDeclaredMethods()} from a local cache in order to avoid the JVM's
* SecurityManager check and defensive array copying.
*/
private static Method[] getDeclaredMethods(Class clazz) {
Method[] result = declaredMethodsCache.get(clazz);
if (result == null) {
result = clazz.getDeclaredMethods();
declaredMethodsCache.put(clazz, result);
}
return result;
}
/**
* Invoke the given callback on all fields in the target class, going up the class hierarchy to get all declared
* fields.
*
* @param clazz
* the target class to analyze
* @param fc
* the callback to invoke for each field
*/
public static void doWithFields(Class clazz, FieldCallback fc) {
doWithFields(clazz, fc, null);
}
/**
* Invoke the given callback on all fields in the target class, going up the class hierarchy to get all declared
* fields.
*
* @param clazz
* 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 clazz, FieldCallback fc, FieldFilter ff) {
// Keep backing up the inheritance hierarchy.
Class targetClass = clazz;
do {
Field[] fields = targetClass.getDeclaredFields();
for (Field field : fields) {
if (ff != null && !ff.matches(field)) {
continue;
}
try {
fc.doWith(field);
} catch (IllegalAccessException ex) {
throw new IllegalStateException("Not allowed to access field '" + field.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.
*/
public static void shallowCopyFieldState(final Object src, final Object dest) {
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() {
@Override
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 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 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 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 MethodFilter USER_DECLARED_METHODS = new MethodFilter() {
@Override
public boolean matches(Method method) {
return (!method.isBridge() && method.getDeclaringClass() != Object.class);
}
};
}