Java tutorial
/** * Copyright (c) 2005-2009 springside.org.cn * * Licensed under the Apache License, Version 2.0 (the "License"); * * $Id: ReflectionUtils.java 384 2009-08-28 14:50:14Z calvinxiu $ */ package com.smart.utils; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.Date; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.commons.beanutils.ConvertUtils; import org.apache.commons.beanutils.PropertyUtils; import org.apache.commons.beanutils.converters.DateConverter; import org.apache.commons.lang.StringUtils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * ??Utils?. * * ?????,?Class,????Utils. * * @author */ public class ReflectionUtils { private static Log logger = LogFactory.getLog(ReflectionUtils.class); /** * ?,private/protected,??getter. */ public static Object getFieldValue(final Object object, final String fieldName) { Field field = getDeclaredField(object, fieldName); if (field == null) throw new IllegalArgumentException( "Could not find field [" + fieldName + "] on target [" + object + "]"); makeAccessible(field); Object result = null; try { result = field.get(object); } catch (IllegalAccessException e) { logger.error("??{}", e); } return result; } /** * ,private/protected,??setter. */ public static void setFieldValue(final Object object, final String fieldName, final Object value) { Field field = getDeclaredField(object, fieldName); if (field == null) throw new IllegalArgumentException( "Could not find field [" + fieldName + "] on target [" + object + "]"); makeAccessible(field); try { field.set(object, value); } catch (IllegalAccessException e) { logger.error("??:{}", e); } } /** * ,private/protected. */ public static Object invokeMethod(final Object object, final String methodName, final Class<?>[] parameterTypes, final Object[] parameters) throws InvocationTargetException { Method method = getDeclaredMethod(object, methodName, parameterTypes); if (method == null) throw new IllegalArgumentException( "Could not find method [" + methodName + "] on target [" + object + "]"); method.setAccessible(true); try { return method.invoke(object, parameters); } catch (IllegalAccessException e) { logger.error("??:{}", e); } return null; } /** * ?,?DeclaredField. */ protected static Field getDeclaredField(final Object object, final String fieldName) { for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { // System.out.println("class:" + superClass); try { return superClass.getDeclaredField(fieldName); } catch (NoSuchFieldException e) { // Field??,? // e.printStackTrace(); // continue; } } return null; } /** * ?,?DeclaredField. */ protected static void makeAccessible(final Field field) { if (!Modifier.isPublic(field.getModifiers()) || !Modifier.isPublic(field.getDeclaringClass().getModifiers())) { field.setAccessible(true); } } /** * ?,?DeclaredMethod. */ protected static Method getDeclaredMethod(Object object, String methodName, Class<?>[] parameterTypes) { for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { return superClass.getDeclaredMethod(methodName, parameterTypes); } catch (NoSuchMethodException e) { // Method??,? } } return null; } /** * ??,Class?. eg. public UserDao extends * HibernateDao<User> * * @param clazz * The class to introspect * @return the first generic declaration, or Object.class if cannot be * determined */ @SuppressWarnings("unchecked") public static <T> Class<T> getSuperClassGenricType(final Class clazz) { return getSuperClassGenricType(clazz, 0); } /** * ??,Class?. * * public UserDao extends HibernateDao<User,Long> * * @param clazz * clazz The class to introspect * @param index * the Index of the generic ddeclaration,start from 0. * @return the index generic declaration, or Object.class if cannot be * determined */ @SuppressWarnings("unchecked") public static Class getSuperClassGenricType(final Class clazz, final int index) { Type genType = clazz.getGenericSuperclass(); if (!(genType instanceof ParameterizedType)) { logger.warn(clazz.getSimpleName() + "'s superclass not ParameterizedType"); return Object.class; } Type[] params = ((ParameterizedType) genType).getActualTypeArguments(); if (index >= params.length || index < 0) { logger.warn("Index: " + index + ", Size of " + clazz.getSimpleName() + "'s Parameterized Type: " + params.length); return Object.class; } if (!(params[index] instanceof Class)) { logger.warn(clazz.getSimpleName() + " not set the actual class on superclass generic parameter"); return Object.class; } return (Class) params[index]; } /** * ????(getter),??List. * * @param collection * ???. * @param propertyName * ??????. */ @SuppressWarnings("unchecked") public static List fetchElementPropertyToList(final Collection collection, final String propertyName) { List list = new ArrayList(); try { for (Object obj : collection) { list.add(PropertyUtils.getProperty(obj, propertyName)); } } catch (Exception e) { convertToUncheckedException(e); } return list; } /** * ????(getter),??. * * @param collection * ???. * @param propertyName * ??????. * @param separator * . */ @SuppressWarnings("unchecked") public static String fetchElementPropertyToString(final Collection collection, final String propertyName, final String separator) { List list = fetchElementPropertyToList(collection, propertyName); return StringUtils.join(list, separator); } /** * ?clazzproperty. * * @param value * ? * @param clazz * ???Class * @param propertyName * ???Class. */ public static Object convertValue(Object value, Class<?> toType) { try { DateConverter dc = new DateConverter(); dc.setUseLocaleFormat(true); dc.setPatterns(new String[] { "yyyy-MM-dd", "yyyy-MM-dd HH:mm:ss" }); ConvertUtils.register(dc, Date.class); return ConvertUtils.convert(value, toType); } catch (Exception e) { throw convertToUncheckedException(e); } } /** * ??checked exception?unchecked exception. */ public static IllegalArgumentException convertToUncheckedException(Exception e) { if (e instanceof IllegalAccessException || e instanceof IllegalArgumentException || e instanceof NoSuchMethodException) return new IllegalArgumentException("Refelction Exception.", e); else return new IllegalArgumentException(e); } /** * beanClass?Annotation * * @return */ public static boolean isAnnotationPresent(String beanClass, Class annotation) { ClassLoader classLoader = annotation.getClassLoader(); Class clz = null; try { clz = classLoader.loadClass(beanClass); } catch (ClassNotFoundException e) { logger.warn("" + beanClass); return false; } return clz.isAnnotationPresent(annotation); } /** * set * * @param bean * @param fieldName * @param setValue */ public static void setValueBySetMethod(Object bean, String fieldName, Object setValue) { if (bean == null || fieldName == null || "".equals(fieldName)) return; Field field = getDeclaredField(bean, fieldName); if (field == null) throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + bean + "]"); Method setMethod = getDeclaredMethod(bean, getSetMethodName(fieldName), new Class<?>[] { field.getType() }); if (setMethod != null) { try { setMethod.invoke(bean, setValue); } catch (Exception e) { logger.error("error methodName=" + setMethod.getName() + " " + e.getMessage(), e); } } } /** * ?pojoget * * @param fieldName * @return */ public static String getGetMethodName(String fieldName) { StringBuffer result = new StringBuffer("get"); String firstChar = fieldName.substring(0, 1); char firstCh = fieldName.charAt(0); // if(firstCh) if (Character.isUpperCase(firstCh)) { result.append(firstCh); } else { result.append(firstChar.toUpperCase()); } result.append(fieldName.substring(1, fieldName.length())); return result.toString(); } /** * ?pojoset * * @param fieldName * @return */ public static String getSetMethodName(String fieldName) { StringBuffer result = new StringBuffer("set"); String firstChar = fieldName.substring(0, 1); char firstCh = fieldName.charAt(0); // if(firstCh) if (Character.isUpperCase(firstCh)) { result.append(firstCh); } else { result.append(firstChar.toUpperCase()); } result.append(fieldName.substring(1, fieldName.length())); return result.toString(); } /** * ?classFieldlistlistField * * @param clz * @return */ public static List<Field> getAllFields(Class clz) { List result = new ArrayList(); Map allFields = new HashMap(); // ??? List classFamilyTree = new LinkedList(); classFamilyTree.add(clz); Class tempSuperClass = clz; while ((tempSuperClass = tempSuperClass.getSuperclass()) != null) { classFamilyTree.add(tempSuperClass); } // Map???field?????? for (int i = classFamilyTree.size() - 1; i >= 0; i--) { Class tempClass = (Class) classFamilyTree.get(i); Field[] fieldsOfTempClass = tempClass.getDeclaredFields(); for (int j = 0; j < fieldsOfTempClass.length; j++) { Field field = fieldsOfTempClass[j]; allFields.put(field.getName(), field); } } // map?list for (Iterator iter = allFields.entrySet().iterator(); iter.hasNext();) { Map.Entry entry = (Map.Entry) iter.next(); result.add(entry.getValue()); } return result; } /** * ?classString,list,listString * * @param clz * @return */ public static List<String> getAllFieldNames(Class clz) { List result = new ArrayList(); Map allFields = new HashMap(); // ??? List classFamilyTree = new LinkedList(); classFamilyTree.add(clz); Class tempSuperClass = clz; while ((tempSuperClass = tempSuperClass.getSuperclass()) != null) { classFamilyTree.add(tempSuperClass); } // Map???field?????? for (int i = classFamilyTree.size() - 1; i >= 0; i--) { Class tempClass = (Class) classFamilyTree.get(i); Field[] fieldsOfTempClass = tempClass.getDeclaredFields(); for (int j = 0; j < fieldsOfTempClass.length; j++) { Field field = fieldsOfTempClass[j]; allFields.put(field.getName(), field.getName()); } } // map?list for (Iterator iter = allFields.entrySet().iterator(); iter.hasNext();) { Map.Entry entry = (Map.Entry) iter.next(); result.add(entry.getValue()); } return result; } /** * ?Class(),ListClass * * @param bean * @return */ public static List<Class> getAllClassesOfClazz(Class clz) { List classFamilyTree = new LinkedList(); classFamilyTree.add(clz); Class tempSuperClass = clz; while ((tempSuperClass = tempSuperClass.getSuperclass()) != null) { classFamilyTree.add(tempSuperClass); } return classFamilyTree; } /** * ?Class??(),Liststring * * @param bean * @return */ public static List<String> getAllClassNameOfClazz(Class clz) { List allClasses = getAllClassesOfClazz(clz); List result = new LinkedList(); for (int i = allClasses.size() - 1; i >= 0; i--) { Class clazz = (Class) allClasses.get(i); result.add(clazz.getName()); } return result; } /** * ?Class?(?),ListClass * * @param bean * @return */ public static List<Class> getAllInterfaceOfClazz(Class clz) { List allClass = getAllClassesOfClazz(clz); // ?? Set s = new HashSet(); for (int i = 0; i < allClass.size(); i++) { Class clazz = (Class) allClass.get(i); List temp = getInterfaceOfClass(clazz); s.addAll(temp); } List result = new LinkedList(); Iterator itrt = s.iterator(); while (itrt.hasNext()) { Class c = (Class) itrt.next(); result.add(c); } return result; } private static List<Class> getInterfaceOfClass(Class clz) { Class[] clazzs = clz.getInterfaces(); List<Class> classFamilyTree = Arrays.asList(clazzs); return new LinkedList(classFamilyTree); } /** * ?Class???(?),Liststring * * @param bean * @return */ public static List<String> getAllInterfaceNameOfClazz(Class clz) { List allInterfaces = getAllInterfaceOfClazz(clz); List result = new LinkedList(); for (int i = allInterfaces.size() - 1; i >= 0; i--) { Class clazz = (Class) allInterfaces.get(i); result.add(clazz.getName()); } return result; } /** * ?getter??,danfo * * @param attName * @return */ public static String getGetterMethodNameOfAttribute(String attName) { attName = attName.trim(); String firstLetter = attName.substring(0, 1); firstLetter = firstLetter.toUpperCase(); // getter?? String methodName = "get" + firstLetter + attName.substring(1, attName.length()); return methodName; } /** * ?????,danfo * * @param bean * @param methodName * @param args * @return */ public static Method getMethodOfBeanByName(Object bean, String methodName, Object[] args) { if (bean == null || methodName == null) { return null; } if (args == null) { Object[] paras = {}; args = paras; } Method method = null; Class beanClass = bean.getClass(); Method[] methods = beanClass.getMethods(); for (int i = methods.length - 1; i >= 0; i--) { Method methodTemp = (Method) methods[i]; String methodNameTemp = methodTemp.getName(); // ??,?? if (methodName.equals(methodNameTemp)) { Class[] paras = methodTemp.getParameterTypes(); // ?? if (paras.length != args.length) { continue; } // ,??? boolean isParaTheSame = true; for (int j = paras.length - 1; j >= 0; j--) { Class paraNeededClass = paras[j]; Class paraGivenClass = args[j].getClass(); if (!paraNeededClass.getName().equals(paraGivenClass.getName())) { isParaTheSame = false; break; } } if (isParaTheSame) { method = methodTemp; } } } return method; // end of methodNameargs } }