me.bird.util.Reflections.java Source code

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Here is the source code for me.bird.util.Reflections.java

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/**
 * Copyright (c) 2005-2011 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: Reflections.java 1661 2011-11-17 20:35:10Z calvinxiu $
 */
package me.bird.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.lang3.StringUtils;
import org.apache.commons.lang3.reflect.FieldUtils;
import org.apache.commons.lang3.reflect.MethodUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * ??.
 * 
 * ??getter/setter, ???, ?, ?Class, AOP.
 * 
 * @author calvin
 */
public class Reflections {

    public static final String CGLIB_CLASS_SEPARATOR = "$$";

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

    private Reflections() {
    }

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

    /**
     * Setter.valueClass?Setter.
     */
    public static void invokeSetter(Object obj, String propertyName, Object value) {
        invokeSetter(obj, propertyName, value, null);
    }

    /**
     * Setter.
     * 
     * @param propertyType Setter,valueClass.
     */
    public static void invokeSetter(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 });
    }

    /**
     * ?, private/protected, ??getter.
     */
    public static Object getFieldValue(final Object obj, final String fieldName) {
        Field field = FieldUtils.getDeclaredField(obj.getClass(), fieldName, true);

        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("??", e);
        }
        return result;
    }

    /**
     * , private/protected, ??setter.
     */
    public static void setFieldValue(final Object obj, final String fieldName, final Object value) {
        //      Field field = FieldUtils.getDeclaredField(obj.getClass(), fieldName, true);
        Field field = FieldUtils.getField(obj.getClass(), fieldName, true);

        if (field == null) {
            throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]");
        }

        try {
            field.set(obj, value);
        } catch (IllegalAccessException e) {
            logger.error("??", e);
        }
    }

    /**
     * cglib AOP, ?Class.
     */
    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;
    }

    /**
     * , private/protected.
     * .
     */
    public static Object invokeMethod(final Object obj, final String methodName, final Class<?>[] parameterTypes,
            final Object[] args) {
        Method method = MethodUtils.getAccessibleMethod(obj.getClass(), 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);
        }
    }

    /**
     * ??, Class?.
     * , 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", "rawtypes" })
    public static <T> Class<T> getSuperClassGenricType(final Class clazz) {
        return getSuperClassGenricType(clazz, 0);
    }

    /**
     * ??, Class?.
     * , Object.class.
     * 
     * public UserDao extends HibernateDao<User,Long>
     *
     * @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 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];
    }

    /**
     * ??checked exception?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);
    }
}