001 /** 002 * Java Gui Builder - A library to build GUIs using an XML file. 003 * Copyright 2002, 2003 (C) François Beausoleil 004 * 005 * This library is free software; you can redistribute it and/or 006 * modify it under the terms of the GNU Lesser General Public 007 * License as published by the Free Software Foundation; either 008 * version 2.1 of the License, or (at your option) any later version. 009 * 010 * This library is distributed in the hope that it will be useful, 011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013 * Lesser General Public License for more details. 014 * 015 * You should have received a copy of the GNU Lesser General Public 016 * License along with this library; if not, write to the Free Software 017 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018 */ 019 020 package jgb.builder.utils; 021 022 import java.lang.reflect.Method; 023 import java.util.Arrays; 024 025 /** 026 * An object that accumulates parameters until such time the caller is ready 027 * to call the specified method. 028 * When the caller is ready to call the method, it calls {@link #call() call()} 029 * to get a reference to the return value of the method. If the named method 030 * returns <code>void</code>, {@link #call() call()} returns 031 * <code>null</code> (just like 032 * {@link java.lang.reflect.Method#invoke(Object, Object[]) Method.invoke(Object, Object[])}). 033 * @since 0.2a 034 * @author Francois Beausoleil, <a href="mailto:fbos@users.sourceforge.net">fbos@users.sourceforge.net</a> 035 */ 036 public class MethodCall extends ParametersAccumulator { 037 private Class calledClass; 038 private String methodName; 039 private Object callingObject; 040 041 protected MethodCall(String className) throws ClassNotFoundException { 042 calledClass = Class.forName(className); 043 } 044 045 public MethodCall(String className, String methodName, Object callingObject) throws ClassNotFoundException, NoSuchMethodException { 046 this(className); 047 this.methodName = methodName; 048 this.callingObject = callingObject; 049 050 checkMethodExists(methodName); 051 } 052 053 public Class getReturnValueType() { 054 try { 055 Method method = findMethod(); 056 return method.getReturnType(); 057 } catch (NoSuchMethodException e) { 058 RuntimeException e1 = 059 new RuntimeException("Could not find method that existed earlier: " 060 + e.getMessage()); 061 e1.printStackTrace(); 062 throw e1; 063 } 064 } 065 066 public String getMethodName() { 067 return methodName; 068 } 069 070 public Class getCalledClass() { 071 return calledClass; 072 } 073 074 public Object call() throws NoSuchMethodException, MethodCallException { 075 try { 076 return findMethod().invoke(callingObject, createValuesArray()); 077 } catch (NoSuchMethodException e) { 078 throw new NoSuchMethodException("Could not execute method " + methodName 079 + " on object's of class " + calledClass + " with parameters " 080 + Arrays.asList(createParametersArray())); 081 } catch (Exception e) { 082 throw new MethodCallException(e); 083 } 084 } 085 086 private Method findMethod() throws NoSuchMethodException { 087 Class[] callingTypes = createParametersArray(); 088 Method[] allMethods = calledClass.getMethods(); 089 for (int i = 0; i < allMethods.length; i++) { 090 Method method = allMethods[i]; 091 if (method.getName().equals(methodName)) { 092 Class[] paramTypes = method.getParameterTypes(); 093 if (paramTypes.length == callingTypes.length) { 094 boolean compatible = true; 095 for (int j = 0; j < paramTypes.length; j++) { 096 if (isCompatible(paramTypes[j], callingTypes[j])) { 097 compatible = false; 098 break; 099 } 100 } 101 102 if (compatible) { 103 return method; 104 } 105 } 106 } 107 } 108 109 throw new NoSuchMethodException("Class " + getCalledClass().getName() 110 + " does not have a method with arguments of type " + getParameterTypes()); 111 } 112 113 private boolean isCompatible(Class type, Class callingType) { 114 return false == type.isAssignableFrom(callingType); 115 } 116 117 private void checkMethodExists(String methodName) throws NoSuchMethodException { 118 boolean methodFound = false; 119 Method[] methods = calledClass.getMethods(); 120 for (int i = 0; i < methods.length; i++) { 121 Method method = methods[i]; 122 if (method.getName().equals(methodName)) { 123 methodFound = true; 124 break; 125 } 126 } 127 128 if (methodFound == false) { 129 throw new NoSuchMethodException("no method with the specified name - " 130 + methodName + " on objects of class " + calledClass.getName()); 131 } 132 } 133 }