Java工具类

BeanUtils.copyProperties排除null属性的copy

import com.hourumiyue.system.SpringUtil;
  
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
  
import java.util.HashSet;
import java.util.Set;
  
public class TestBeanUtiles {
  
    public static String[] getNullPropertyNames (Object source) {
        final BeanWrapper src = new BeanWrapperImpl(source);
        java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors();
  
        Set<String> emptyNames = new HashSet<String>();
        for(java.beans.PropertyDescriptor pd : pds) {
            Object srcValue = src.getPropertyValue(pd.getName());
            if (srcValue == null) emptyNames.add(pd.getName());
        }
        String[] result = new String[emptyNames.size()];
        return emptyNames.toArray(result);
    }
  
    //封装同名称属性复制，但是空属性不复制过去
    public static void copyPropertiesIgnoreNull(Object src, Object target){
        BeanUtils.copyProperties(src, target, getNullPropertyNames(src));
    }
     
    public static void main(String[] args) {
        NewPerson newPerson = new NewPerson();
        newPerson.setName("miyue");//前台用户更新过的数据，例如前台只修改了用户名
        //下面我们假设是从数据库加载出来的老数据
        OldPerson oldPerson = new OldPerson();
        oldPerson.setSex("nv");
        oldPerson.setAge(5);
        //如果我们想把新数据更新到老数据这个对象里面，我们就可以借助BeanUtils.copyProperties()的方法如下：
        //BeanUtils.copyProperties(newPerson, oldPerson);
        copyPropertiesIgnoreNull(newPerson, oldPerson);
        System.out.println(newPerson.toString());
        System.out.println(oldPerson.toString());
    }
}