001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019
020package org.apache.bytecode;
021
022import java.io.IOException;
023import java.lang.reflect.Method;
024import java.lang.reflect.Proxy;
025
026/**
027 * This class retrieves function parameter names from bytecode built with
028 * debugging symbols.  Used as a last resort when creating WSDL.
029 */
030public class ParamNameExtractor {
031
032    /**
033     * Retrieves a list of function parameter names from a method. 
034     * Returns null if unable to read parameter names (i.e. bytecode not
035     * built with debug).
036     */
037    public static String[] getParameterNamesFromDebugInfo(Method method) {
038        // Don't worry about it if there are no params.
039        int numParams = method.getParameterTypes().length;
040        if (numParams == 0)
041            return null;
042
043        // get declaring class
044        Class c = method.getDeclaringClass();
045
046        // Don't worry about it if the class is a Java dynamic proxy
047        if (Proxy.isProxyClass(c)) {
048            return null;
049        }
050
051        try {
052            // get a parameter reader
053            ParamReader pr = new ParamReader(c);
054            // get the parameter names
055            return pr.getParameterNames(method);
056        } catch (IOException e) {
057            // log it and leave
058            return null;
059        }
060    }
061}