001/*
002 * Copyright 2002-2017 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.core;
018
019import java.lang.reflect.Constructor;
020import java.lang.reflect.Method;
021import java.lang.reflect.Parameter;
022
023import org.springframework.lang.Nullable;
024
025/**
026 * {@link ParameterNameDiscoverer} implementation which uses JDK 8's reflection facilities
027 * for introspecting parameter names (based on the "-parameters" compiler flag).
028 *
029 * @author Juergen Hoeller
030 * @since 4.0
031 * @see java.lang.reflect.Method#getParameters()
032 * @see java.lang.reflect.Parameter#getName()
033 */
034public class StandardReflectionParameterNameDiscoverer implements ParameterNameDiscoverer {
035
036        @Override
037        @Nullable
038        public String[] getParameterNames(Method method) {
039                return getParameterNames(method.getParameters());
040        }
041
042        @Override
043        @Nullable
044        public String[] getParameterNames(Constructor<?> ctor) {
045                return getParameterNames(ctor.getParameters());
046        }
047
048        @Nullable
049        private String[] getParameterNames(Parameter[] parameters) {
050                String[] parameterNames = new String[parameters.length];
051                for (int i = 0; i < parameters.length; i++) {
052                        Parameter param = parameters[i];
053                        if (!param.isNamePresent()) {
054                                return null;
055                        }
056                        parameterNames[i] = param.getName();
057                }
058                return parameterNames;
059        }
060
061}