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/*
* Copyright (c) 2008-2019 The Aspectran Project
*
* 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 com.aspectran.core.util;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* Simple utility class for working with the reflection API.
*
* @since 2.0.0
*/
public class ReflectionUtils {
/**
* 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.
*
* @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 e) {
throw new IllegalStateException("Could not access field: " + field, e);
}
}
/**
* 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.
*
* @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 e) {
throw new IllegalStateException("Could not access field: " + field, e);
}
}
/**
* 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}.
*
* @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 (InvocationTargetException | IllegalAccessException e) {
throw new IllegalStateException("Could not access method: " + method, ExceptionUtils.getRootCause(e));
}
}
/**
* Algorithm that judges the match between the declared parameter types of
* a candidate method and a specific list of arguments that this method is
* supposed to be invoked with.
*
* @param paramTypes the parameter types to match
* @param destArgs the arguments to match
* @return the accumulated weight for all arguments
*/
public static float getTypeDifferenceWeight(Class[] paramTypes, Object[] destArgs) {
if (paramTypes.length != destArgs.length) {
return Float.MAX_VALUE;
}
float weight = 0.0f;
for (int i = 0; i < paramTypes.length; i++) {
Class srcClass = paramTypes[i];
Object destArg = destArgs[i];
weight += getTypeDifferenceWeight(srcClass, destArg);
if (weight == Float.MAX_VALUE) {
break;
}
}
return weight;
}
/**
* Algorithm that judges the match between the declared parameter types of
* a candidate method and a specific list of arguments that this method is
* supposed to be invoked with.
*
* @param paramType the parameter type to match
* @param destArg the argument to match
* @return the type difference weight
*/
public static float getTypeDifferenceWeight(Class paramType, Object destArg) {
if (!TypeUtils.isAssignableValue(paramType, destArg)) {
return Float.MAX_VALUE;
}
return getTypeDifferenceWeight(paramType, (destArg != null ? destArg.getClass() : null));
}
/**
* Returns the sum of the object transformation cost for each class in the source
* argument list.
*
* @param srcArgs the source arguments
* @param destArgs the destination arguments
* @return the accumulated weight for all arguments
*/
public static float getTypeDifferenceWeight(Class[] srcArgs, Class[] destArgs) {
float weight = 0.0f;
for (int i = 0; i < srcArgs.length; i++) {
Class srcClass = srcArgs[i];
Class destClass = destArgs[i];
weight += getTypeDifferenceWeight(srcClass, destClass);
if (weight == Float.MAX_VALUE) {
break;
}
}
return weight;
}
/**
* Gets the number of steps required needed to turn the source class into the
* destination class. This represents the number of steps in the object hierarchy
* graph.
*
* @param srcClass the source class
* @param destClass the destination class
* @return the cost of transforming an object
*/
public static float getTypeDifferenceWeight(Class srcClass, Class destClass) {
if (srcClass == null) {
return Float.MAX_VALUE;
}
if (destClass != null) {
if (srcClass.isArray() && destClass.isArray()) {
srcClass = srcClass.getComponentType();
destClass = destClass.getComponentType();
}
if ((destClass.isPrimitive()
&& srcClass.equals(TypeUtils.getPrimitiveWrapper(destClass)))
|| (srcClass.isPrimitive()
&& destClass.equals(TypeUtils.getPrimitiveWrapper(srcClass)))) {
return 0.1f;
}
}
float weight = 0.0f;
while (destClass != null) {
if (destClass.equals(srcClass)) {
if (destClass.isInterface()) {
// slight penalty for interface match.
// we still want an exact match to override an interface match, but
// an interface match should override anything where we have to get a
// superclass.
weight += 0.25f;
}
break;
}
weight++;
destClass = destClass.getSuperclass();
}
/*
* If the destination class is null, we've travelled all the way up to
* an Object match. We'll penalize this by adding 1.5 to the cost.
*/
if (destClass == null) {
weight += 1.5f;
}
return weight;
}
/**
* Converts an array of objects to an array of their primitive types.
*
* @param val an array of objects to be converted, may be {@code null}
* @return an array of their primitive types
*/
public static Object toPrimitiveArray(Object val) {
if (val instanceof Boolean[]) {
int len = Array.getLength(val);
boolean[] arr = new boolean[len];
for (int i = 0; i < len; i++) {
arr[i] = (Boolean)Array.get(val, i);
}
return arr;
} else if (val instanceof Byte[]) {
int len = Array.getLength(val);
byte[] arr = new byte[len];
for (int i = 0; i < len; i++) {
arr[i] = (Byte)Array.get(val, i);
}
return arr;
} else if (val instanceof Character[]) {
int len = Array.getLength(val);
char[] arr = new char[len];
for (int i = 0; i < len; i++) {
arr[i] = (Character)Array.get(val, i);
}
return arr;
} else if (val instanceof Short[]) {
int len = Array.getLength(val);
short[] arr = new short[len];
for (int i = 0; i < len; i++) {
arr[i] = (Short)Array.get(val, i);
}
return arr;
} else if (val instanceof Integer[]) {
int len = Array.getLength(val);
int[] arr = new int[len];
for (int i = 0; i < len; i++) {
arr[i] = (Integer)Array.get(val, i);
}
return arr;
} else if (val instanceof Long[]) {
int len = Array.getLength(val);
long[] arr = new long[len];
for (int i = 0; i < len; i++) {
arr[i] = (Long)Array.get(val, i);
}
return arr;
} else if (val instanceof Float[]) {
int len = Array.getLength(val);
float[] arr = new float[len];
for (int i = 0; i < len; i++) {
arr[i] = (Float)Array.get(val, i);
}
return arr;
} else if (val instanceof Double[]) {
int len = Array.getLength(val);
double[] arr = new double[len];
for (int i = 0; i < len; i++) {
arr[i] = (Double)Array.get(val, i);
}
return arr;
} else {
return null;
}
}
/**
* Converts an array of objects to an array of the specified component type.
*
* @param val an array of objects to be converted
* @param componentType the {@code Class} object representing the component type of the new array
* @return an array of the objects with the specified component type
*/
public static Object toComponentTypeArray(Object val, Class componentType) {
if (val != null) {
int len = Array.getLength(val);
Object arr = Array.newInstance(componentType, len);
for (int i = 0; i < len; i++) {
Array.set(arr, i, Array.get(val, i));
}
return arr;
} else {
return null;
}
}
}
