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.dosport.system.utils; import java.io.File; import java.io.IOException; 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.net.URL; import java.util.ArrayList; import java.util.List; import org.apache.commons.lang.StringUtils; 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) { 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 + "]"); } 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({ "rawtypes", "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("rawtypes") 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); } public static List<Class<?>> getAllAssignedClass(Class<?> cls) throws IOException, ClassNotFoundException { List<Class<?>> classes = new ArrayList<Class<?>>(); for (Class<?> c : getClasses(cls)) { if (cls.isAssignableFrom(c) && !cls.equals(c)) { classes.add(c); } } return classes; } /** * ?? * * @param cls * @return * @throws IOException * @throws ClassNotFoundException */ public static List<Class<?>> getClasses(Class<?> cls) throws IOException, ClassNotFoundException { String pk = cls.getPackage().getName(); String path = pk.replace('.', '/'); ClassLoader classloader = Thread.currentThread().getContextClassLoader(); URL url = classloader.getResource(path); return getClasses(new File(url.getFile()), pk); } /** * * * @param dir * @param pk * @return * @throws ClassNotFoundException */ private static List<Class<?>> getClasses(File dir, String pk) throws ClassNotFoundException { List<Class<?>> classes = new ArrayList<Class<?>>(); if (!dir.exists()) { return classes; } for (File f : dir.listFiles()) { if (f.isDirectory()) { classes.addAll(getClasses(f, pk + "." + f.getName())); } String name = f.getName(); if (name.endsWith(".class")) { classes.add(Class.forName(pk + "." + name.substring(0, name.length() - 6))); } } return classes; } }