org.springframework.messaging.handler.invocation.AbstractExceptionHandlerMethodResolver Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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.messaging.handler.invocation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.springframework.core.ExceptionDepthComparator;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ConcurrentReferenceHashMap;
/**
* Cache exception handling method mappings and provide options to look up a method
* that should handle an exception. If multiple methods match, they are sorted using
* {@link ExceptionDepthComparator} and the top match is returned.
*
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 4.0
*/
public abstract class AbstractExceptionHandlerMethodResolver {
private final Map, Method> mappedMethods = new HashMap<>(16);
private final Map, Method> exceptionLookupCache = new ConcurrentReferenceHashMap<>(16);
/**
* Protected constructor accepting exception-to-method mappings.
*/
protected AbstractExceptionHandlerMethodResolver(Map, Method> mappedMethods) {
Assert.notNull(mappedMethods, "Mapped Methods must not be null");
this.mappedMethods.putAll(mappedMethods);
}
/**
* Extract the exceptions this method handles.This implementation looks for
* sub-classes of Throwable in the method signature.
* The method is static to ensure safe use from sub-class constructors.
*/
@SuppressWarnings("unchecked")
protected static List> getExceptionsFromMethodSignature(Method method) {
List> result = new ArrayList<>();
for (Class paramType : method.getParameterTypes()) {
if (Throwable.class.isAssignableFrom(paramType)) {
result.add((Class) paramType);
}
}
if (result.isEmpty()) {
throw new IllegalStateException("No exception types mapped to " + method);
}
return result;
}
/**
* Whether the contained type has any exception mappings.
*/
public boolean hasExceptionMappings() {
return !this.mappedMethods.isEmpty();
}
/**
* Find a {@link Method} to handle the given exception.
* Use {@link ExceptionDepthComparator} if more than one match is found.
* @param exception the exception
* @return a Method to handle the exception, or {@code null} if none found
*/
@Nullable
public Method resolveMethod(Throwable exception) {
Method method = resolveMethodByExceptionType(exception.getClass());
if (method == null) {
Throwable cause = exception.getCause();
if (cause != null) {
method = resolveMethodByExceptionType(cause.getClass());
}
}
return method;
}
/**
* Find a {@link Method} to handle the given exception type. This can be
* useful if an {@link Exception} instance is not available (e.g. for tools).
* @param exceptionType the exception type
* @return a Method to handle the exception, or {@code null} if none found
* @since 4.3.1
*/
@Nullable
public Method resolveMethodByExceptionType(Class exceptionType) {
Method method = this.exceptionLookupCache.get(exceptionType);
if (method == null) {
method = getMappedMethod(exceptionType);
this.exceptionLookupCache.put(exceptionType, method);
}
return method;
}
/**
* Return the {@link Method} mapped to the given exception type, or {@code null} if none.
*/
@Nullable
private Method getMappedMethod(Class exceptionType) {
List> matches = new ArrayList<>();
for (Class mappedException : this.mappedMethods.keySet()) {
if (mappedException.isAssignableFrom(exceptionType)) {
matches.add(mappedException);
}
}
if (!matches.isEmpty()) {
matches.sort(new ExceptionDepthComparator(exceptionType));
return this.mappedMethods.get(matches.get(0));
}
else {
return null;
}
}
}