反射工具类.

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 org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 反射工具类.
 * 
 * 提供调用getter/setter方法, 访问私有变量, 调用私有方法, 获取泛型类型Class, 被AOP过的真实类等工具函数.
 */
public class Reflections {
	private static final String SETTER_PREFIX = "set";

	private static final String GETTER_PREFIX = "get";

	private static final String CGLIB_CLASS_SEPARATOR = "$$";

	private static Logger logger = LoggerFactory.getLogger(Reflections.class);

	/**
	 * 调用Getter方法.
	 */
	public static Object invokeGetter(Object obj, String propertyName) {
		String getterMethodName = GETTER_PREFIX + StringUtils.capitalize(propertyName);
		return invokeMethod(obj, getterMethodName, new Class[] {}, new Object[] {});
	}

	/**
	 * 调用Setter方法, 仅匹配方法名。
	 */
	public static void invokeSetter(Object obj, String propertyName, Object value) {
		String setterMethodName = SETTER_PREFIX + StringUtils.capitalize(propertyName);
		invokeMethodByName(obj, setterMethodName, new Object[] { value });
	}

	/**
	 * 直接读取对象属性值, 无视private/protected修饰符, 不经过getter函数.
	 */
	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("不可能抛出的异常{}", e.getMessage());
		}
		return result;
	}

	/**
	 * 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
	 */
	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("不可能抛出的异常:{}", e.getMessage());
		}
	}

	/**
	 * 直接调用对象方法, 无视private/protected修饰符. 用于一次性调用的情况，否则应使用getAccessibleMethod()函数获得Method后反复调用. 同时匹配方法名+参数类型，
	 */
	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);
		}
	}

	/**
	 * 直接调用对象方法, 无视private/protected修饰符， 用于一次性调用的情况，否则应使用getAccessibleMethodByName()函数获得Method后反复调用.
	 * 只匹配函数名，如果有多个同名函数调用第一个。
	 */
	public static Object invokeMethodByName(final Object obj, final String methodName, final Object[] args) {
		Method method = getAccessibleMethodByName(obj, methodName);
		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);
		}
	}

	/**
	 * 循环向上转型, 获取对象的DeclaredField, 并强制设置为可访问.
	 * 
	 * 如向上转型到Object仍无法找到, 返回null.
	 */
	public static Field getAccessibleField(final Object obj, final String fieldName) {
		Validate.notNull(obj, "object can't be null");
		Validate.notBlank(fieldName, "fieldName can't be blank");
		for (Class
  superClass = obj.getClass(); superClass != Object.class; superClass = superClass
				.getSuperclass()) {
			try {
				Field field = superClass.getDeclaredField(fieldName);
				makeAccessible(field);
				return field;
			} catch (NoSuchFieldException e) {// NOSONAR
				// Field不在当前类定义,继续向上转型
			}
		}
		return null;
	}

	/**
	 * 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null. 匹配函数名+参数类型。
	 * 
	 * 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj, Object... args)
	 */
	public static Method getAccessibleMethod(final Object obj, final String methodName,
			final Class
 ... parameterTypes) {
		Validate.notNull(obj, "object can't be null");
		Validate.notBlank(methodName, "methodName can't be blank");

		for (Class
  searchType = obj.getClass(); searchType != Object.class; searchType = searchType
				.getSuperclass()) {
			try {
				Method method = searchType.getDeclaredMethod(methodName, parameterTypes);
				makeAccessible(method);
				return method;
			} catch (NoSuchMethodException e) {
				// Method不在当前类定义,继续向上转型
			}
		}
		return null;
	}

	/**
	 * 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null. 只匹配函数名。
	 * 
	 * 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj, Object... args)
	 */
	public static Method getAccessibleMethodByName(final Object obj, final String methodName) {
		Validate.notNull(obj, "object can't be null");
		Validate.notBlank(methodName, "methodName can't be blank");

		for (Class
  searchType = obj.getClass(); searchType != Object.class; searchType = searchType
				.getSuperclass()) {
			Method[] methods = searchType.getDeclaredMethods();
			for (Method method : methods) {
				if (method.getName().equals(methodName)) {
					makeAccessible(method);
					return method;
				}
			}
		}
		return null;
	}

	/**
	 * 改变private/protected的方法为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
	 */
	public static void makeAccessible(Method method) {
		if ((!Modifier.isPublic(method.getModifiers()) || !Modifier.isPublic(method.getDeclaringClass().getModifiers()))
				&& !method.isAccessible()) {
			method.setAccessible(true);
		}
	}

	/**
	 * 改变private/protected的成员变量为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
	 */
	public static void makeAccessible(Field field) {
		if ((!Modifier.isPublic(field.getModifiers()) || !Modifier.isPublic(field.getDeclaringClass().getModifiers())
				|| Modifier.isFinal(field.getModifiers())) && !field.isAccessible()) {
			field.setAccessible(true);
		}
	}

	/**
	 * 通过反射, 获得Class定义中声明的泛型参数的类型, 注意泛型必须定义在父类处 如无法找到, 返回Object.class. eg. public UserDao extends HibernateDao
 
  
	 * 
	 * @param clazz The class to introspect
	 * @return the first generic declaration, or Object.class if cannot be determined
	 */
	@SuppressWarnings({ "unchecked", "rawtypes" })
	public static 
  
    Class
   
     getClassGenricType(final Class clazz) { return getClassGenricType(clazz, 0); } /** * 通过反射, 获得Class定义中声明的父类的泛型参数的类型. 如无法找到, 返回Object.class. * * 如public UserDao extends HibernateDao
    
      * * @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 getClassGenricType(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]; } /** * 获取CGLib处理过后的实体的原类. */ @SuppressWarnings("rawtypes") public static Class
      getUserClass(Object instance) { Validate.notNull(instance, "Instance must not be null"); Class clazz = instance.getClass(); if ((clazz != null) && clazz.getName().contains(CGLIB_CLASS_SEPARATOR)) { Class
      superClass = clazz.getSuperclass(); if ((superClass != null) && !Object.class.equals(superClass)) { return superClass; } } return clazz; } /** * 将反射时的checked exception转换为unchecked exception. */ public static RuntimeException convertReflectionExceptionToUnchecked(Exception e) { if ((e instanceof IllegalAccessException) || (e instanceof IllegalArgumentException) || (e instanceof NoSuchMethodException)) { return new IllegalArgumentException(e); } else if (e instanceof InvocationTargetException) { return new RuntimeException(((InvocationTargetException) e).getTargetException()); } else if (e instanceof RuntimeException) { return (RuntimeException) e; } return new RuntimeException("Unexpected Checked Exception.", e); } }