/* * Copyright 2002-2017 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 * * 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 org.springframework.core; import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.util.LinkedList; import java.util.List; /** * {@link ParameterNameDiscoverer} implementation that tries several discoverer * delegates in succession. Those added first in the {@code addDiscoverer} method * have highest priority. If one returns {@code null}, the next will be tried. * * <p>The default behavior is to return {@code null} if no discoverer matches. * * @author Rod Johnson * @author Juergen Hoeller * @since 2.0 */ public class PrioritizedParameterNameDiscoverer implements ParameterNameDiscoverer { private final List<ParameterNameDiscoverer> parameterNameDiscoverers = new LinkedList<>(); /** * Add a further {@link ParameterNameDiscoverer} delegate to the list of * discoverers that this {@code PrioritizedParameterNameDiscoverer} checks. */ public void addDiscoverer(ParameterNameDiscoverer pnd) { this.parameterNameDiscoverers.add(pnd); } @Override public String[] getParameterNames(Method method) { for (ParameterNameDiscoverer pnd : this.parameterNameDiscoverers) { String[] result = pnd.getParameterNames(method); if (result != null) { return result; } } return null; } @Override public String[] getParameterNames(Constructor<?> ctor) { for (ParameterNameDiscoverer pnd : this.parameterNameDiscoverers) { String[] result = pnd.getParameterNames(ctor); if (result != null) { return result; } } return null; } }