org.springframework.beans.factory.support.AutowireUtils 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.beans.factory.support;
import java.beans.PropertyDescriptor;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.Executable;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Set;
import org.springframework.beans.BeanMetadataElement;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.TypedStringValue;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* Utility class that contains various methods useful for the implementation of
* autowire-capable bean factories.
*
* @author Juergen Hoeller
* @author Mark Fisher
* @author Sam Brannen
* @since 1.1.2
* @see AbstractAutowireCapableBeanFactory
*/
abstract class AutowireUtils {
public static final Comparator EXECUTABLE_COMPARATOR = (e1, e2) -> {
int result = Boolean.compare(Modifier.isPublic(e2.getModifiers()), Modifier.isPublic(e1.getModifiers()));
return result != 0 ? result : Integer.compare(e2.getParameterCount(), e1.getParameterCount());
};
/**
* Sort the given constructors, preferring public constructors and "greedy" ones with
* a maximum number of arguments. The result will contain public constructors first,
* with decreasing number of arguments, then non-public constructors, again with
* decreasing number of arguments.
* @param constructors the constructor array to sort
*/
public static void sortConstructors(Constructor[] constructors) {
Arrays.sort(constructors, EXECUTABLE_COMPARATOR);
}
/**
* Sort the given factory methods, preferring public methods and "greedy" ones
* with a maximum of arguments. The result will contain public methods first,
* with decreasing number of arguments, then non-public methods, again with
* decreasing number of arguments.
* @param factoryMethods the factory method array to sort
*/
public static void sortFactoryMethods(Method[] factoryMethods) {
Arrays.sort(factoryMethods, EXECUTABLE_COMPARATOR);
}
/**
* Determine whether the given bean property is excluded from dependency checks.
* This implementation excludes properties defined by CGLIB.
* @param pd the PropertyDescriptor of the bean property
* @return whether the bean property is excluded
*/
public static boolean isExcludedFromDependencyCheck(PropertyDescriptor pd) {
Method wm = pd.getWriteMethod();
if (wm == null) {
return false;
}
if (!wm.getDeclaringClass().getName().contains("$$")) {
// Not a CGLIB method so it's OK.
return false;
}
// It was declared by CGLIB, but we might still want to autowire it
// if it was actually declared by the superclass.
Class superclass = wm.getDeclaringClass().getSuperclass();
return !ClassUtils.hasMethod(superclass, wm);
}
/**
* Return whether the setter method of the given bean property is defined
* in any of the given interfaces.
* @param pd the PropertyDescriptor of the bean property
* @param interfaces the Set of interfaces (Class objects)
* @return whether the setter method is defined by an interface
*/
public static boolean isSetterDefinedInInterface(PropertyDescriptor pd, Set> interfaces) {
Method setter = pd.getWriteMethod();
if (setter != null) {
Class targetClass = setter.getDeclaringClass();
for (Class ifc : interfaces) {
if (ifc.isAssignableFrom(targetClass) && ClassUtils.hasMethod(ifc, setter)) {
return true;
}
}
}
return false;
}
/**
* Resolve the given autowiring value against the given required type,
* e.g. an {@link ObjectFactory} value to its actual object result.
* @param autowiringValue the value to resolve
* @param requiredType the type to assign the result to
* @return the resolved value
*/
public static Object resolveAutowiringValue(Object autowiringValue, Class requiredType) {
if (autowiringValue instanceof ObjectFactory && !requiredType.isInstance(autowiringValue)) {
ObjectFactory factory = (ObjectFactory) autowiringValue;
if (autowiringValue instanceof Serializable && requiredType.isInterface()) {
autowiringValue = Proxy.newProxyInstance(requiredType.getClassLoader(),
new Class[] {requiredType}, new ObjectFactoryDelegatingInvocationHandler(factory));
}
else {
return factory.getObject();
}
}
return autowiringValue;
}
/**
* Determine the target type for the generic return type of the given
* generic factory method, where formal type variables are declared
* on the given method itself.
* For example, given a factory method with the following signature, if
* {@code resolveReturnTypeForFactoryMethod()} is invoked with the reflected
* method for {@code createProxy()} and an {@code Object[]} array containing
* {@code MyService.class}, {@code resolveReturnTypeForFactoryMethod()} will
* infer that the target return type is {@code MyService}.
*
{@code public static T createProxy(Class clazz)}
* Possible Return Values
*
* - the target return type, if it can be inferred
* - the {@linkplain Method#getReturnType() standard return type}, if
* the given {@code method} does not declare any {@linkplain
* Method#getTypeParameters() formal type variables}
* - the {@linkplain Method#getReturnType() standard return type}, if the
* target return type cannot be inferred (e.g., due to type erasure)
* - {@code null}, if the length of the given arguments array is shorter
* than the length of the {@linkplain
* Method#getGenericParameterTypes() formal argument list} for the given
* method
*
* @param method the method to introspect (never {@code null})
* @param args the arguments that will be supplied to the method when it is
* invoked (never {@code null})
* @param classLoader the ClassLoader to resolve class names against,
* if necessary (never {@code null})
* @return the resolved target return type or the standard method return type
* @since 3.2.5
*/
public static Class resolveReturnTypeForFactoryMethod(
Method method, Object[] args, @Nullable ClassLoader classLoader) {
Assert.notNull(method, "Method must not be null");
Assert.notNull(args, "Argument array must not be null");
TypeVariable[] declaredTypeVariables = method.getTypeParameters();
Type genericReturnType = method.getGenericReturnType();
Type[] methodParameterTypes = method.getGenericParameterTypes();
Assert.isTrue(args.length == methodParameterTypes.length, "Argument array does not match parameter count");
// Ensure that the type variable (e.g., T) is declared directly on the method
// itself (e.g., via ), not on the enclosing class or interface.
boolean locallyDeclaredTypeVariableMatchesReturnType = false;
for (TypeVariable currentTypeVariable : declaredTypeVariables) {
if (currentTypeVariable.equals(genericReturnType)) {
locallyDeclaredTypeVariableMatchesReturnType = true;
break;
}
}
if (locallyDeclaredTypeVariableMatchesReturnType) {
for (int i = 0; i < methodParameterTypes.length; i++) {
Type methodParameterType = methodParameterTypes[i];
Object arg = args[i];
if (methodParameterType.equals(genericReturnType)) {
if (arg instanceof TypedStringValue) {
TypedStringValue typedValue = ((TypedStringValue) arg);
if (typedValue.hasTargetType()) {
return typedValue.getTargetType();
}
try {
Class resolvedType = typedValue.resolveTargetType(classLoader);
if (resolvedType != null) {
return resolvedType;
}
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException("Failed to resolve value type [" +
typedValue.getTargetTypeName() + "] for factory method argument", ex);
}
}
else if (arg != null && !(arg instanceof BeanMetadataElement)) {
// Only consider argument type if it is a simple value...
return arg.getClass();
}
return method.getReturnType();
}
else if (methodParameterType instanceof ParameterizedType) {
ParameterizedType parameterizedType = (ParameterizedType) methodParameterType;
Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
for (Type typeArg : actualTypeArguments) {
if (typeArg.equals(genericReturnType)) {
if (arg instanceof Class) {
return (Class) arg;
}
else {
String className = null;
if (arg instanceof String) {
className = (String) arg;
}
else if (arg instanceof TypedStringValue) {
TypedStringValue typedValue = ((TypedStringValue) arg);
String targetTypeName = typedValue.getTargetTypeName();
if (targetTypeName == null || Class.class.getName().equals(targetTypeName)) {
className = typedValue.getValue();
}
}
if (className != null) {
try {
return ClassUtils.forName(className, classLoader);
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException("Could not resolve class name [" + arg +
"] for factory method argument", ex);
}
}
// Consider adding logic to determine the class of the typeArg, if possible.
// For now, just fall back...
return method.getReturnType();
}
}
}
}
}
}
// Fall back...
return method.getReturnType();
}
/**
* Reflective {@link InvocationHandler} for lazy access to the current target object.
*/
@SuppressWarnings("serial")
private static class ObjectFactoryDelegatingInvocationHandler implements InvocationHandler, Serializable {
private final ObjectFactory objectFactory;
ObjectFactoryDelegatingInvocationHandler(ObjectFactory objectFactory) {
this.objectFactory = objectFactory;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
switch (method.getName()) {
case "equals":
// Only consider equal when proxies are identical.
return (proxy == args[0]);
case "hashCode":
// Use hashCode of proxy.
return System.identityHashCode(proxy);
case "toString":
return this.objectFactory.toString();
}
try {
return method.invoke(this.objectFactory.getObject(), args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
}