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封装了mybatis的crud
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package com.zys.mybatis.utils;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;

import java.lang.reflect.Field;
import java.util.*;

/**
 * @author zys
 * @version 1.0
 * @date 2020/10/21 18:44
 */
@Slf4j
public class BeanUtil {

    /**
     *
     * @param source 源对象list
     * @param target 目标对象
     * @param 
     * @return
     */
    public static  List copyList(List source, Class target){
        List targets = new ArrayList<>();
        try {
            for (Object o : source) {
                Object t = target.newInstance();
                BeanUtils.copyProperties(o,t);
                targets.add((T) t);
            }
        } catch (InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        }
        return targets;
    }

    private static String[] getNullPropertyNames (Object source) {
        return getNames(source,false);
    }

    /**
     *
     * @param obj 忽略的对象
     * @param flag true 有值,false null
     * @return
     */
    private static String[] getNames(Object obj,Boolean flag){
        final BeanWrapper src = new BeanWrapperImpl(obj);
        java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors();

        Set emptyNames = new HashSet<>();
        for(java.beans.PropertyDescriptor pd : pds) {
            Object srcValue = src.getPropertyValue(pd.getName());
            if (flag) {
                if (srcValue != null) emptyNames.add(pd.getName());
            }else {
                if (srcValue == null) emptyNames.add(pd.getName());
            }
        }
        String[] result = new String[emptyNames.size()];
        return emptyNames.toArray(result);
    }

    private static String[] getPropertyNames(Object target){
        return getNames(target,true);
    }

    /**
     * 忽略源对象为空的属性
     * @param src 源对象
     * @param target 目标对象
     */
    public static void copyPropertiesIgnoreNull(Object src, Object target){
        BeanUtils.copyProperties(src, target, getNullPropertyNames(src));
    }

    public static  T[] concat(T[] first, T[] second) {
        T[] result = Arrays.copyOf(first, first.length + second.length);
        System.arraycopy(second, 0, result, first.length, second.length);
        return result;
    }

    private static String[] getNullPropertyNames(Object src, Object target){
        return concat(getNullPropertyNames(src), getPropertyNames(target));
    }

    /**
     * 通过反射获取对象某个属性的值
     * @param object 对象
     * @param fieldName 字段名称
     * @return
     */
    public static Object getValue(Object object,String fieldName){
        Class aClass = object.getClass();
        try {
            Field field = aClass.getDeclaredField(fieldName);
            field.setAccessible(true);
            return field.get(object);
        } catch (NoSuchFieldException e) {
            log.error("未找到字段:{}",fieldName);
        } catch (IllegalAccessException e) {
            log.error("获取值失败:{}",fieldName);
        }
        return null;
    }

    /**
     * 复制源对象为空的属性 和 目标对象有值的属性
     * @param src 源对象
     * @param target 目标对象
     */
    public static void copyPropertiesIgnoreNullAndIgnoreTargetValue(Object src, Object target){
        BeanUtils.copyProperties(src, target, getNullPropertyNames(src,target));
    }

}