Java tutorial
// //$Id: IntrospectionUtil.java 1540 2007-01-19 12:24:10Z janb $ //Copyright 2006 Mort Bay Consulting Pty. Ltd. //------------------------------------------------------------------------ //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. // import java.lang.reflect.Field; import java.lang.reflect.Member; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.util.Arrays; import java.util.List; public class IntrospectionUtil { public static Field findField(Class clazz, String targetName, Class targetType, boolean checkInheritance, boolean strictType) throws NoSuchFieldException { if (clazz == null) throw new NoSuchFieldException("No class"); if (targetName == null) throw new NoSuchFieldException("No field name"); try { Field field = clazz.getDeclaredField(targetName); if (strictType) { if (field.getType().equals(targetType)) return field; } else { if (field.getType().isAssignableFrom(targetType)) return field; } if (checkInheritance) { return findInheritedField(clazz.getPackage(), clazz.getSuperclass(), targetName, targetType, strictType); } else throw new NoSuchFieldException("No field with name " + targetName + " in class " + clazz.getName() + " of type " + targetType); } catch (NoSuchFieldException e) { return findInheritedField(clazz.getPackage(), clazz.getSuperclass(), targetName, targetType, strictType); } } public static boolean isInheritable(Package pack, Member member) { if (pack == null) return false; if (member == null) return false; int modifiers = member.getModifiers(); if (Modifier.isPublic(modifiers)) return true; if (Modifier.isProtected(modifiers)) return true; if (!Modifier.isPrivate(modifiers) && pack.equals(member.getDeclaringClass().getPackage())) return true; return false; } public static boolean checkParams(Class[] formalParams, Class[] actualParams, boolean strict) { if (formalParams == null && actualParams == null) return true; if (formalParams == null && actualParams != null) return false; if (formalParams != null && actualParams == null) return false; if (formalParams.length != actualParams.length) return false; if (formalParams.length == 0) return true; int j = 0; if (strict) { while (j < formalParams.length && formalParams[j].equals(actualParams[j])) j++; } else { while ((j < formalParams.length) && (formalParams[j].isAssignableFrom(actualParams[j]))) { j++; } } if (j != formalParams.length) { return false; } return true; } public static boolean isSameSignature(Method methodA, Method methodB) { if (methodA == null) return false; if (methodB == null) return false; List parameterTypesA = Arrays.asList(methodA.getParameterTypes()); List parameterTypesB = Arrays.asList(methodB.getParameterTypes()); if (methodA.getName().equals(methodB.getName()) && parameterTypesA.containsAll(parameterTypesB)) return true; return false; } public static boolean isTypeCompatible(Class formalType, Class actualType, boolean strict) { if (formalType == null && actualType != null) return false; if (formalType != null && actualType == null) return false; if (formalType == null && actualType == null) return true; if (strict) return formalType.equals(actualType); else return formalType.isAssignableFrom(actualType); } public static boolean containsSameMethodSignature(Method method, Class c, boolean checkPackage) { if (checkPackage) { if (!c.getPackage().equals(method.getDeclaringClass().getPackage())) return false; } boolean samesig = false; Method[] methods = c.getDeclaredMethods(); for (int i = 0; i < methods.length && !samesig; i++) { if (IntrospectionUtil.isSameSignature(method, methods[i])) samesig = true; } return samesig; } public static boolean containsSameFieldName(Field field, Class c, boolean checkPackage) { if (checkPackage) { if (!c.getPackage().equals(field.getDeclaringClass().getPackage())) return false; } boolean sameName = false; Field[] fields = c.getDeclaredFields(); for (int i = 0; i < fields.length && !sameName; i++) { if (fields[i].getName().equals(field.getName())) sameName = true; } return sameName; } protected static Method findInheritedMethod(Package pack, Class clazz, String methodName, Class[] args, boolean strictArgs) throws NoSuchMethodException { if (clazz == null) throw new NoSuchMethodException("No class"); if (methodName == null) throw new NoSuchMethodException("No method name"); Method method = null; Method[] methods = clazz.getDeclaredMethods(); for (int i = 0; i < methods.length && method == null; i++) { if (methods[i].getName().equals(methodName) && isInheritable(pack, methods[i]) && checkParams(methods[i].getParameterTypes(), args, strictArgs)) method = methods[i]; } if (method != null) { return method; } else return findInheritedMethod(clazz.getPackage(), clazz.getSuperclass(), methodName, args, strictArgs); } protected static Field findInheritedField(Package pack, Class clazz, String fieldName, Class fieldType, boolean strictType) throws NoSuchFieldException { if (clazz == null) throw new NoSuchFieldException("No class"); if (fieldName == null) throw new NoSuchFieldException("No field name"); try { Field field = clazz.getDeclaredField(fieldName); if (isInheritable(pack, field) && isTypeCompatible(fieldType, field.getType(), strictType)) return field; else return findInheritedField(clazz.getPackage(), clazz.getSuperclass(), fieldName, fieldType, strictType); } catch (NoSuchFieldException e) { return findInheritedField(clazz.getPackage(), clazz.getSuperclass(), fieldName, fieldType, strictType); } } }