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package com.github.antelopeframework.util;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.apache.commons.lang3.StringUtils;
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.
 * 
 * @author 杨志
 */
public abstract class BeanUtil {

	public static final String CGLIB_CLASS_SEPARATOR = "$$";

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

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

	/**
	 * 调用Setter方法.使用value的Class来查找Setter方法.
	 */
	public static void invokeSetterMethod(Object obj, String propertyName, Object value) {
		invokeSetterMethod(obj, propertyName, value, null);
	}

	/**
	 * 调用Setter方法.
	 * 
	 * @param propertyType 用于查找Setter方法,为空时使用value的Class替代.
	 */
	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 });
	}

	/**
	 * 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());
		}
	}

	/**
	 * 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) {
		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不在当前类定义,继续向上转型
			}
		}

		return null;
	}

	/**
	 * 对于被cglib AOP过的对象, 取得真实的Class类型.
	 */
	public static Class getUserClass(Class clazz) {
		if (clazz != null && clazz.getName().contains(CGLIB_CLASS_SEPARATOR)) {
			Class superClass = clazz.getSuperclass();
			if (superClass != null && !Object.class.equals(superClass)) {
				return superClass;
			}
		}
		return clazz;
	}

	/**
	 * 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.
	 */
	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);
		}
	}

	/**
	 * 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.
	 * 
	 * 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) {
		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不在当前类定义,继续向上转型
			}
		}
		return null;
	}

	/**
	 * 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("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);
	}
}