ReflectionUtils.java

package jakiro.util;

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;

public class ReflectionUtils {

    /**
     * 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 object, final String fieldName, final 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) {

        }
    }

    /**
     * 直接读取对象属性值,无视private/protected修饰符,不经过getter函数.
     */
    public static Object getFieldValue(final Object object, final 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;
    }

    /**
     * 直接调用对象方法,无视private/protected修饰符.
     */
    public static Object invokeMethod(final Object object, final String methodName, final Class<?>[] parameterTypes, final 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;
    }

    /**
     * 循环向上转型,获取对象的DeclaredField.
     */
    public static Field getDeclaredField(final Object object, final String fieldName) {
        for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
            try {
                return superClass.getDeclaredField(fieldName);
            } catch (NoSuchFieldException e) {
            }
        }
        return null;
    }

    /**
     * 循环向上转型,获取对象的DeclaredField.
     */
    public static void makeAccessible(final Field field) {
        if (!Modifier.isPublic(field.getModifiers()) || !Modifier.isPublic(field.getDeclaringClass().getModifiers())) {
            field.setAccessible(true);
        }
    }

    /**
     * 循环向上转型,获取对象的DeclaredMethod.
     */
    public static Method getDeclaredMethod(Object object, String methodName, Class<?>[] parameterTypes) {
        for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
            try {
                return superClass.getDeclaredMethod(methodName, parameterTypes);
            } catch (NoSuchMethodException e) {

            }
        }
        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. 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(@SuppressWarnings("rawtypes") 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. 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("rawtypes")
    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 IllegalArgumentException convertToUncheckedException(Exception e) {
        if (e instanceof IllegalAccessException || e instanceof IllegalArgumentException || e instanceof NoSuchMethodException)
            return new IllegalArgumentException("Refelction Exception.", e);
        else
            return new IllegalArgumentException(e);
    }
}