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.Date;
import java.util.ArrayList;
import java.util.Collection;
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;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;
/**
* 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
* @author Administrator
*
*/
public class ReflectionUtils {
private static Logger logger = LoggerFactory.getLogger(ReflectionUtils.class);
/**
* 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<Employee, String>
* @param clazz
* @param index
* @return
*/
@SuppressWarnings("unchecked")
public static Class getSuperClassGenricType(Class clazz, 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];
}
/**
* 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<Employee, String>
* @param <T>
* @param clazz
* @return
*/
@SuppressWarnings("unchecked")
public static<T> Class<T> 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){
Assert.notNull(object, "object 不能为空");
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){
Assert.notNull(object, "object 不能为空");
Assert.hasText(filedName, "fieldName");
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) {
logger.error("不可能抛出的异常:{}", e.getMessage());
}
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) {
logger.error("不可能抛出的异常:{}", e.getMessage());
}
}
/**
* 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) {
logger.error("不可能抛出的异常{}", e.getMessage());
}
return result;
}
}