/**
* Copyright (c) 2005-2010 springside.org.cn
* Licensed under the Apache License, Version 2.0 (the "License");
*/
package com.szewec.base.common.util;
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 org.apache.commons.lang.StringUtils;
import org.apache.log4j.Logger;
/**
* 反射工具类.
*
* 提供访问私有变量,获取泛型类型Class, 提取集合中元素的属性, 转换字符串到对象等Util函数.
*
* @author lby
*/
public class ReflectionUtils {
private static Logger logger = Logger.getLogger(ReflectionUtils.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) {
if (obj == null)
throw new IllegalArgumentException("object不能为空");
if (fieldName == null || fieldName.equals(""))
throw new IllegalArgumentException("fieldName不能为空");
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) {
// Field不在当前类定义,继续向上转型
}
}
return null;
}
/**
* 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) {
if (obj == null)
throw new IllegalArgumentException("object不能为空");
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) {
// Method不在当前类定义,继续向上转型
}
}
return null;
}
/**
* 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.
* 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);
}
/**
* 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<User,Long>
*
* @param clazz clazz The class to introspect
* @param index the Index of the generic declaration,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];
}
/**
* 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);
}
}