Java tutorial
/** * Copyright (c) 2005-2010 springside.org.cn * * Licensed under the Apache License, Version 2.0 (the "License"); * * $Id: ReflectionUtils.java 1211 2010-09-10 16:20:45Z calvinxiu $ */ package com.test.edusys.common.utils.reflection; import java.lang.annotation.Annotation; 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 java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.lang3.StringUtils; import org.nutz.dao.entity.annotation.Comment; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.util.Assert; /** * ??. * * ?????,?Class, ????, ?Util. * * @author calvin */ public class ReflectionUtils { private static Logger logger = LoggerFactory.getLogger(ReflectionUtils.class); /** * Getter. */ public static Object invokeGetterMethod(Object obj, String propertyName) { String getterMethodName = "get" + StringUtils.capitalize(propertyName); return invokeMethod(obj, getterMethodName, new Class[] {}, new Object[] {}); } /** * Setter.valueClass?Setter. */ public static void invokeSetterMethod(Object obj, String propertyName, Object value) { //valuenull if (value == null) { value = ""; } invokeSetterMethod(obj, propertyName, value, null); } /** * Setter. * * @param propertyType Setter,valueClass. */ 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 }); } /** * ?, private/protected, ??getter. */ 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; } /** * , private/protected, ??setter. */ 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()); } } /** * ?, ?DeclaredField, ?. * * ?Object?, null. */ 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; } /** * , private/protected. * . */ 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 + "]"); return null; } try { return method.invoke(obj, args); } catch (Exception e) { throw convertReflectionExceptionToUnchecked(e); } } /** * ?, ?DeclaredMethod,?. * ?Object?, null. * * ?. ?Method,?Method.invoke(Object obj, Object... args) */ 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; } /** * ??, Class?. * , Object.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?. * , Object.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]; } /** * ??checked exception?unchecked exception. */ 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); } /** * ? */ @SuppressWarnings("unchecked") public static boolean hasField(final Class clazz, final String fieldName) { Assert.notNull(clazz, "object?"); Assert.hasText(fieldName, "fieldName"); for (Class<?> superClass = clazz; superClass != Object.class; superClass = superClass.getSuperclass()) { try { superClass.getDeclaredField(fieldName); return true; } catch (NoSuchFieldException e) {//NOSONAR // Field??,? } } return false; } /** * */ public static String getKeyFieldName(final Class clazz) { Field[] fields = clazz.getDeclaredFields(); for (Field f : fields) { String filedName = f.getName(); Annotation[] annotation = f.getAnnotations(); for (Annotation annotation2 : annotation) { Class annotationType = annotation2.annotationType(); if (annotationType.getName().equals("org.nutz.dao.entity.annotation.Id")) return filedName; if (annotationType.getName().equals("org.nutz.dao.entity.annotation.Name")) return filedName; } } return null; } /** * Comment? */ public static Map<String, String> getCommentName(final Class clazz) { Field[] fields = clazz.getDeclaredFields(); Map<String, String> map = new HashMap<String, String>(); for (Field f : fields) { Annotation[] aAnnotation = f.getAnnotations(); for (Annotation annotation : aAnnotation) { if (annotation.annotationType() == Comment.class) { Comment element = (Comment) annotation; map.put(f.getName(), element.value()); } } } return map; } /** * */ public static List<String> getShowLogFieldName(final Class clazz) { List<String> lS = new ArrayList<String>(); Field[] fields = clazz.getDeclaredFields(); for (Field f : fields) { String filedName = f.getName(); Annotation[] annotation = f.getAnnotations(); for (Annotation annotation2 : annotation) { if (annotation2.annotationType() == ShowLog.class) lS.add(filedName); } } return lS; } /** * */ public static String getShowLogTablename(final Class clazz) { Annotation[] classAnnotation = clazz.getAnnotations(); for (Annotation cAnnotation : classAnnotation) { if (ShowLogTablename.class == cAnnotation.annotationType()) { ShowLogTablename xmlElement = (ShowLogTablename) cAnnotation; return xmlElement.value(); } } return null; } public static void main(String[] args) { //User user = new User(); //invokeSetterMethod(user, "xm","test"); //System.out.println(new Gson().toJson(user)); } /** * objectmap * @param obj * @return * @throws Exception */ public static Map<String, Object> objectToMap(Object obj) throws Exception { if (obj == null) { return null; } Map<String, Object> map = new HashMap<String, Object>(); Field[] declaredFields = obj.getClass().getDeclaredFields(); for (Field field : declaredFields) { field.setAccessible(true); map.put(field.getName(), field.get(obj)); } return map; } }