ReflectionUtils工具类代码

package cn.itcast.java.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.Collection; import java.util.Date; import java.util.List; 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; /** * * 反射的 Utils 函数集合 * 提供访问私有变量, 获取泛型类型 Class, 提取集合中元素属性等 Utils 函数 * */ public class ReflectionUtils { /** * 将反射时的 "检查异常" 转换为 "运行时异常" * @return */ public static IllegalArgumentException convertToUncheckedException(Exception ex){ if(ex instanceof IllegalAccessException || ex instanceof IllegalArgumentException || ex instanceof NoSuchMethodException){ throw new IllegalArgumentException("反射异常", ex); }else{ throw new IllegalArgumentException(ex); } } /** * 转换字符串类型到 toType 类型, 或 toType 转为字符串 * @param value: 待转换的字符串 * @param toType: 提供类型信息的 Class, 可以是基本数据类型的包装类或指定格式日期型 * @return */ 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) { e.printStackTrace(); throw convertToUncheckedException(e); } } /** * 提取集合中的对象的属性(通过 getter 方法), 组成 List * @param collection: 来源集合 * @param propertyName: 要提取的属性名 * @return */ @SuppressWarnings("unchecked") public static List fetchElementPropertyToList(Collection collection, String propertyName){ List list = new ArrayList(); try { for(Object obj: collection){ list.add(PropertyUtils.getProperty(obj, propertyName)); } } catch (Exception e) { e.printStackTrace(); convertToUncheckedException(e); } return list; } /** * 提取集合中的对象属性(通过 getter 函数), 组合成由分隔符分隔的字符串 * @param collection: 来源集合 * @param propertyName: 要提取的属性名 * @param seperator: 分隔符 * @return */ @SuppressWarnings("unchecked") public static String fetchElementPropertyToString(Collection collection, String propertyName, String seperator){ List list = fetchElementPropertyToList(collection, propertyName); return StringUtils.join(list, seperator); } /** * 通过反射, 获得定义 Class 时声明的父类的泛型参数的类型 * 如: public EmployeeDao extends BaseDao * @param clazz * @param index * @return */ @SuppressWarnings("unchecked") public static Class getSuperClassGenricType(Class clazz, int index){ Type genType = clazz.getGenericSuperclass(); if(!(genType instanceof ParameterizedType)){ return Object.class; } Type [] params = ((ParameterizedType)genType).getActualTypeArguments(); if(index >= params.length || index < 0){ return Object.class; } if(!(params[index] instanceof Class)){ return Object.class; } return (Class) params[index]; } /** * 通过反射, 获得 Class 定义中声明的父类的泛型参数类型 * 如: public EmployeeDao extends BaseDao * @param * @param clazz * @return */ @SuppressWarnings("unchecked") public static Class getSuperGenericType(Class clazz){ return getSuperClassGenricType(clazz, 0); } /** * 循环向上转型, 获取对象的 DeclaredMethod * @param object * @param methodName * @param parameterTypes * @return */ public static Method getDeclaredMethod(Object object, String methodName, Class[] parameterTypes){ for(Class superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()){ try { //superClass.getMethod(methodName, parameterTypes); return superClass.getDeclaredMethod(methodName, parameterTypes); } catch (NoSuchMethodException e) { //Method 不在当前类定义, 继续向上转型 } //.. } return null; } /** * 使 filed 变为可访问 * @param field */ public static void makeAccessible(Field field){ if(!Modifier.isPublic(field.getModifiers())){ field.setAccessible(true); } } /** * 循环向上转型, 获取对象的 DeclaredField * @param object * @param filedName * @return */ public static Field getDeclaredField(Object object, String filedName){ for(Class superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()){ try { return superClass.getDeclaredField(filedName); } catch (NoSuchFieldException e) { //Field 不在当前类定义, 继续向上转型 } } return null; } /** * 直接调用对象方法, 而忽略修饰符(private, protected) * @param object * @param methodName * @param parameterTypes * @param parameters * @return * @throws InvocationTargetException * @throws IllegalArgumentException */ public static Object invokeMethod(Object object, String methodName, Class [] parameterTypes, 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) { } return null; } /** * 直接设置对象属性值, 忽略 private/protected 修饰符, 也不经过 setter * @param object * @param fieldName * @param value */ public static void setFieldValue(Object object, String fieldName, 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) { } } /** * 直接读取对象的属性值, 忽略 private/protected 修饰符, 也不经过 getter * @param object * @param fieldName * @return */ public static Object getFieldValue(Object object, 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) { } return result; } }