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package com.github.youyinnn.youdbutils.utils;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;

/**
 * 提供反射相关方法.
 *
 * @author youyinnn
 */
public class ReflectionUtils {

    /**
     * 使 filed 变为可访问
     *
     * @param field the field
     */
    private static void fieldAccessible(Field field){
        if (!Modifier.isPublic(field.getModifiers())) {
            field.setAccessible(true);
        }
    }

    /**
     * 循环向上转型 获取对象的这个field
     *
     * @param o         the o
     * @param fieldName the field name
     * @return the declared field
     */
    private static Field getDeclaredField(Object o, String fieldName) {
        for (
                Class superclass = o.getClass() ;
                superclass != Object.class ;
                superclass = superclass.getSuperclass()
                ) {
            try {
                return superclass.getDeclaredField(fieldName);
            } catch (NoSuchFieldException ignored) {
                //Field 不在当前类定义, 继续向上转型
            }
        }
        return null;
    }

    /**
     * 获取对象中有对应注解的所有field
     *
     * @param o          the o
     * @param annotation the annotation
     * @return the declared fields
     */
    public static ArrayList getDeclaredFields(Object o, Class annotation) {

        ArrayList fieldList = new ArrayList<>();

        for (
                Class superClass = o.getClass();
                superClass != Object.class;
                superClass = superClass.getSuperclass()
                ) {
            Field[] declaredFields = superClass.getDeclaredFields();

            for (Field declaredField : declaredFields) {
                Annotation annotation1 = declaredField.getAnnotation(annotation);

                if (annotation1 != null) {
                    fieldList.add(declaredField);
                }
            }
        }

        return fieldList;
    }

    /**
     * 直接设置对象属性值, 忽略 private/protected 修饰符, 也不经过 setter
     *
     * @param o         the o
     * @param fieldName the field name
     * @param value     the value
     */
    public static void setFieldValue(Object o, String fieldName, Object value) {
        Field field = getDeclaredField(o, fieldName);

        if (field == null) {
            throw new IllegalArgumentException("No such field [ "+fieldName+" ] in class [ " +o.getClass().getSimpleName()+ " ]." );
        }

        fieldAccessible(field);

        try {
            field.set(o, value);
        } catch (IllegalAccessException ignore) {

        }
    }

    /**
     * 直接读取对象的属性值, 忽略 private/protected 修饰符, 也不经过 getter
     *
     * @param o         the o
     * @param fieldName the field name
     * @return object object
     */
    public static Object getFieldValue(Object o, String fieldName){
        Field field = getDeclaredField(o, fieldName);

        if (field == null) {
            throw new IllegalArgumentException("No such field [ "+fieldName+" ] in class [ " +o.getClass().getSimpleName()+ " ]." );
        }

        fieldAccessible(field);

        Object result = null;

        try {
            result = field.get(o);
        } catch (IllegalAccessException ignore) {

        }

        return result;
    }

}