org.springframework.core.annotation.SynthesizedMergedAnnotationInvocationHandler Maven / Gradle / Ivy
/*
* Copyright 2002-2020 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
*
* https://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.core.annotation;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.concurrent.ConcurrentHashMap;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.ReflectionUtils;
/**
* {@link InvocationHandler} for an {@link Annotation} that Spring has
* synthesized (i.e. wrapped in a dynamic proxy) with additional
* functionality such as attribute alias handling.
*
* @author Sam Brannen
* @author Phillip Webb
* @since 5.2
* @param the annotation type
* @see Annotation
* @see AnnotationUtils#synthesizeAnnotation(Annotation, AnnotatedElement)
*/
final class SynthesizedMergedAnnotationInvocationHandler implements InvocationHandler {
private final MergedAnnotation annotation;
private final Class type;
private final AttributeMethods attributes;
private final Map valueCache = new ConcurrentHashMap<>(8);
@Nullable
private volatile Integer hashCode;
@Nullable
private volatile String string;
private SynthesizedMergedAnnotationInvocationHandler(MergedAnnotation annotation, Class type) {
Assert.notNull(annotation, "MergedAnnotation must not be null");
Assert.notNull(type, "Type must not be null");
Assert.isTrue(type.isAnnotation(), "Type must be an annotation");
this.annotation = annotation;
this.type = type;
this.attributes = AttributeMethods.forAnnotationType(type);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) {
if (ReflectionUtils.isEqualsMethod(method)) {
return annotationEquals(args[0]);
}
if (ReflectionUtils.isHashCodeMethod(method)) {
return annotationHashCode();
}
if (ReflectionUtils.isToStringMethod(method)) {
return annotationToString();
}
if (isAnnotationTypeMethod(method)) {
return this.type;
}
if (this.attributes.indexOf(method.getName()) != -1) {
return getAttributeValue(method);
}
throw new AnnotationConfigurationException(String.format(
"Method [%s] is unsupported for synthesized annotation type [%s]", method, this.type));
}
private boolean isAnnotationTypeMethod(Method method) {
return (method.getName().equals("annotationType") && method.getParameterCount() == 0);
}
/**
* See {@link Annotation#equals(Object)} for a definition of the required algorithm.
* @param other the other object to compare against
*/
private boolean annotationEquals(Object other) {
if (this == other) {
return true;
}
if (!this.type.isInstance(other)) {
return false;
}
for (int i = 0; i < this.attributes.size(); i++) {
Method attribute = this.attributes.get(i);
Object thisValue = getAttributeValue(attribute);
Object otherValue = ReflectionUtils.invokeMethod(attribute, other);
if (!ObjectUtils.nullSafeEquals(thisValue, otherValue)) {
return false;
}
}
return true;
}
/**
* See {@link Annotation#hashCode()} for a definition of the required algorithm.
*/
private int annotationHashCode() {
Integer hashCode = this.hashCode;
if (hashCode == null) {
hashCode = computeHashCode();
this.hashCode = hashCode;
}
return hashCode;
}
private Integer computeHashCode() {
int hashCode = 0;
for (int i = 0; i < this.attributes.size(); i++) {
Method attribute = this.attributes.get(i);
Object value = getAttributeValue(attribute);
hashCode += (127 * attribute.getName().hashCode()) ^ getValueHashCode(value);
}
return hashCode;
}
private int getValueHashCode(Object value) {
// Use Arrays.hashCode(...) since Spring's ObjectUtils doesn't comply
// with the requirements specified in Annotation#hashCode().
if (value instanceof boolean[]) {
return Arrays.hashCode((boolean[]) value);
}
if (value instanceof byte[]) {
return Arrays.hashCode((byte[]) value);
}
if (value instanceof char[]) {
return Arrays.hashCode((char[]) value);
}
if (value instanceof double[]) {
return Arrays.hashCode((double[]) value);
}
if (value instanceof float[]) {
return Arrays.hashCode((float[]) value);
}
if (value instanceof int[]) {
return Arrays.hashCode((int[]) value);
}
if (value instanceof long[]) {
return Arrays.hashCode((long[]) value);
}
if (value instanceof short[]) {
return Arrays.hashCode((short[]) value);
}
if (value instanceof Object[]) {
return Arrays.hashCode((Object[]) value);
}
return value.hashCode();
}
private String annotationToString() {
String string = this.string;
if (string == null) {
StringBuilder builder = new StringBuilder("@").append(this.type.getName()).append('(');
for (int i = 0; i < this.attributes.size(); i++) {
Method attribute = this.attributes.get(i);
if (i > 0) {
builder.append(", ");
}
builder.append(attribute.getName());
builder.append('=');
builder.append(toString(getAttributeValue(attribute)));
}
builder.append(')');
string = builder.toString();
this.string = string;
}
return string;
}
private String toString(Object value) {
if (value instanceof Class) {
return ((Class) value).getName();
}
if (value.getClass().isArray()) {
StringBuilder builder = new StringBuilder("[");
for (int i = 0; i < Array.getLength(value); i++) {
if (i > 0) {
builder.append(", ");
}
builder.append(toString(Array.get(value, i)));
}
builder.append(']');
return builder.toString();
}
return String.valueOf(value);
}
private Object getAttributeValue(Method method) {
Object value = this.valueCache.computeIfAbsent(method.getName(), attributeName -> {
Class type = ClassUtils.resolvePrimitiveIfNecessary(method.getReturnType());
return this.annotation.getValue(attributeName, type).orElseThrow(
() -> new NoSuchElementException("No value found for attribute named '" + attributeName +
"' in merged annotation " + this.annotation.getType().getName()));
});
// Clone non-empty arrays so that users cannot alter the contents of values in our cache.
if (value.getClass().isArray() && Array.getLength(value) > 0) {
value = cloneArray(value);
}
return value;
}
/**
* Clone the provided array, ensuring that the original component type is retained.
* @param array the array to clone
*/
private Object cloneArray(Object array) {
if (array instanceof boolean[]) {
return ((boolean[]) array).clone();
}
if (array instanceof byte[]) {
return ((byte[]) array).clone();
}
if (array instanceof char[]) {
return ((char[]) array).clone();
}
if (array instanceof double[]) {
return ((double[]) array).clone();
}
if (array instanceof float[]) {
return ((float[]) array).clone();
}
if (array instanceof int[]) {
return ((int[]) array).clone();
}
if (array instanceof long[]) {
return ((long[]) array).clone();
}
if (array instanceof short[]) {
return ((short[]) array).clone();
}
// else
return ((Object[]) array).clone();
}
@SuppressWarnings("unchecked")
static A createProxy(MergedAnnotation annotation, Class type) {
ClassLoader classLoader = type.getClassLoader();
InvocationHandler handler = new SynthesizedMergedAnnotationInvocationHandler<>(annotation, type);
Class[] interfaces = isVisible(classLoader, SynthesizedAnnotation.class) ?
new Class[] {type, SynthesizedAnnotation.class} : new Class[] {type};
return (A) Proxy.newProxyInstance(classLoader, interfaces, handler);
}
private static boolean isVisible(ClassLoader classLoader, Class interfaceClass) {
if (classLoader == interfaceClass.getClassLoader()) {
return true;
}
try {
return Class.forName(interfaceClass.getName(), false, classLoader) == interfaceClass;
}
catch (ClassNotFoundException ex) {
return false;
}
}
}