Source code
package org.springframework.core;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
/**
* Defines the algorithm for searching for metadata-associated methods exhaustively
* including interfaces and parent classes while also dealing with parameterized methods
* as well as common scenarios encountered with interface and class-based proxies.
*
* <p>Typically, but not necessarily, used for finding annotated handler methods.
*
* @author Juergen Hoeller
* @author Rossen Stoyanchev
* @author Sam Brannen
* @since 4.2.3
*/
public final class MethodIntrospector {
private MethodIntrospector() {
}
/**
* Select methods on the given target type based on the lookup of associated metadata.
* <p>Callers define methods of interest through the {@link MetadataLookup} parameter,
* allowing to collect the associated metadata into the result map.
* @param targetType the target type to search methods on
* @param metadataLookup a {@link MetadataLookup} callback to inspect methods of interest,
* returning non-null metadata to be associated with a given method if there is a match,
* or {@code null} for no match
* @return the selected methods associated with their metadata (in the order of retrieval),
* or an empty map in case of no match
*/
public static <T> Map<Method, T> select(Class<?> target, final MetadataLookup<T> metadata) {
final Map<Method, T> method2 = new LinkedHashMap<>();
Set<Class<?>> handler = new LinkedHashSet<>();
Class<?> specific = null;
if (!Proxy.isProxyClass(target)) {
specific = ClassUtils.getUserClass(target);
handler.add(specific);
}
handler.addAll(ClassUtils.getAllInterfacesForClassAsSet(target));
for (Class<?> current : handler) {
final Class<?> target2 = (specific != null ? specific : current);
ReflectionUtils.doWithMethods(current, method -> {
Method specific2 = ClassUtils.getMostSpecificMethod(method, target2);
T res = metadata.inspect(specific2);
if (res != null) {
Method bridged = BridgeMethodResolver.findBridgedMethod(specific2);
if (bridged == specific2 || bridged == method ||
bridged.equals(specific2) || bridged.equals(method) ||
metadata.inspect(bridged) == null) {
method2.put(specific2, res);
}
}
}, ReflectionUtils.USER_DECLARED_METHODS);
}
return method2;
}
/**
* Select methods on the given target type based on a filter.
* <p>Callers define methods of interest through the {@code MethodFilter} parameter.
* @param targetType the target type to search methods on
* @param methodFilter a {@code MethodFilter} to help
* recognize handler methods of interest
* @return the selected methods, or an empty set in case of no match
*/
public static Set<Method> select(Class<?> target3, final ReflectionUtils.MethodFilter method3) {
return select(target3,
(MetadataLookup<Boolean>) method -> (method3.matches(method) ? Boolean.TRUE : null)).keySet();
}
/**
* Select an invocable method on the target type: either the given method itself
* if actually exposed on the target type, or otherwise a corresponding method
* on one of the target type's interfaces or on the target type itself.
* <p>Matches on user-declared interfaces will be preferred since they are likely
* to contain relevant metadata that corresponds to the method on the target class.
* @param method the method to check
* @param targetType the target type to search methods on
* (typically an interface-based JDK proxy)
* @return a corresponding invocable method on the target type
* @throws IllegalStateException if the given method is not invocable on the given
* target type (typically due to a proxy mismatch)
*/
public static Method select2(Method met, Class<?> target4) {
if (met.getDeclaringClass().isAssignableFrom(target4)) {
return met;
}
try {
String method = met.getName();
Class<?>[] parameter = met.getParameterTypes();
for (Class<?> ifc : target4.getInterfaces()) {
try {
return ifc.getMethod(method, parameter);
}
catch (NoSuchMethodException ex) {
// Alright, not on this interface then...
}
}
// A final desperate attempt on the proxy class itself...
return target4.getMethod(method, parameter);
}
catch (NoSuchMethodException ex) {
throw new IllegalStateException(String.format(
"Need to invoke method '%s' declared on target class '%s', " +
"but not found in any interface(s) of the exposed proxy type. " +
"Either pull the method up to an interface or switch to CGLIB " +
"proxies by enforcing proxy-target-class mode in your configuration.",
met.getName(), met.getDeclaringClass().getSimpleName()));
}
}
/**
* A callback interface for metadata lookup on a given method.
* @param <T> the type of metadata returned
*/
@FunctionalInterface
public interface MetadataLookup<T> {
/**
* Perform a lookup on the given method and return associated metadata, if any.
* @param method the method to inspect
* @return non-null metadata to be associated with a method if there is a match,
* or {@code null} for no match
*/
@Nullable T ins(Method met2);
}
}