Java tutorial
/* * $RCSfile: ReflectionUtils,v $$ * $Revision: 1.0 $ * $Date: 2011 $ * * Copyright (C) 2011 GyTech, Inc. All rights reserved. * * This software is the proprietary information of GyTech, Inc. * Use is subject to license terms. */ package com.xhsoft.framework.common.utils; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import org.apache.commons.lang.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.util.Assert; /** * <p>Title:ReflectionUtils</p> * <p>Description:??.?????,?Class, ????, ?Util.</p> * <p>Copyright:Copyright (C) 2011</p> * @author gkm * @since 2011 */ public class ReflectionUtils { private static Logger logger = LoggerFactory.getLogger(ReflectionUtils.class); /** * <p>Description: Getter.</p> * @param obj * @param propertyName * @return Object */ public static Object invokeGetterMethod(Object obj, String propertyName) { String getterMethodName = "get" + StringUtils.capitalize(propertyName); return invokeMethod(obj, getterMethodName, new Class[] {}, new Object[] {}); } /** * <p>Description:Setter.valueClass?Setter.</p> * @param obj * @param propertyName * @param value * @return void */ public static void invokeSetterMethod(Object obj, String propertyName, Object value) { invokeSetterMethod(obj, propertyName, value, null); } /** * <p>Description:Setter.</p> * @param obj * @param propertyName * @param value * @param propertyType Setter,valueClass. * @return void */ public static void invokeSetterMethod(Object obj, String propertyName, Object value, Class<?> propertyType) { Class<?> type = propertyType != null ? propertyType : value.getClass(); String setterMethodName = "set" + StringUtils.capitalize(propertyName); invokeMethod(obj, setterMethodName, new Class[] { type }, new Object[] { value }); } /** * <p>Description:?, private/protected, ??getter.</p> * @param obj * @param fieldName * @return Object */ public static Object getFieldValue(final Object obj, final String fieldName) { Field field = getAccessibleField(obj, fieldName); if (field == null) { throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]"); } Object result = null; try { result = field.get(obj); } catch (IllegalAccessException e) { logger.error("??{}", e.getMessage()); } return result; } /** * <p>Description:, private/protected, ??setter..</p> * @param obj * @param fieldName * @param value * @return void */ public static void setFieldValue(final Object obj, final String fieldName, final Object value) { Field field = getAccessibleField(obj, fieldName); if (field == null) { throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]"); } try { field.set(obj, value); } catch (IllegalAccessException e) { logger.error("??:{}", e.getMessage()); } } /** * <p>Description:?, ?DeclaredField, ?.?Object?, null.</p> * @param obj * @param fieldName * @return Field */ public static Field getAccessibleField(final Object obj, final String fieldName) { Assert.notNull(obj, "object?"); Assert.hasText(fieldName, "fieldName"); for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { Field field = superClass.getDeclaredField(fieldName); field.setAccessible(true); return field; } catch (NoSuchFieldException e) {//NOSONAR /* Field??,?*/ } } return null; } /** * <p>Description:, private/protected..</p> * @param obj * @param methodName * @param parameterTypes * @param args * @return Object */ public static Object invokeMethod(final Object obj, final String methodName, final Class<?>[] parameterTypes, final Object[] args) { Method method = getAccessibleMethod(obj, methodName, parameterTypes); if (method == null) { throw new IllegalArgumentException( "Could not find method [" + methodName + "] on target [" + obj + "]"); } try { return method.invoke(obj, args); } catch (Exception e) { throw convertReflectionExceptionToUnchecked(e); } } /** * <p>Description:?, ?DeclaredMethod,?. * ?Object?, null. * ?. ?Method,?Method.invoke(Object obj, Object... args) * </p> * @param obj * @param methodName * @param parameterTypes * @return Method */ public static Method getAccessibleMethod(final Object obj, final String methodName, final Class<?>... parameterTypes) { Assert.notNull(obj, "object?"); for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { Method method = superClass.getDeclaredMethod(methodName, parameterTypes); method.setAccessible(true); return method; } catch (NoSuchMethodException e) {//NOSONAR /* Method??,?*/ } } return null; } /** * <p>Description:??, Class?. * , Object.class. * eg. * public UserDao extends HibernateDao<User> * </p> * @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); } /** * <p>Description:??, Class?., Object.class. * public UserDao extends HibernateDao<User,Long> * </p> * @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]; } /** * <p>Description:??checked exception?unchecked exception.</p> * @param e * @return RuntimeException */ public static RuntimeException convertReflectionExceptionToUnchecked(Exception e) { if (e instanceof IllegalAccessException || e instanceof IllegalArgumentException || e instanceof NoSuchMethodException) { return new IllegalArgumentException("Reflection Exception.", e); } else if (e instanceof InvocationTargetException) { return new RuntimeException("Reflection Exception.", ((InvocationTargetException) e).getTargetException()); } else if (e instanceof RuntimeException) { return (RuntimeException) e; } return new RuntimeException("Unexpected Checked Exception.", e); } }