BeanUtils.copyProperties 选择性赋值字段

public class User {

    private String name;

    private Integer age;
        // 省略get/set方法
}

User use = new User();
use.setName("jeremy");
use.setAge(23);
User newUser = new User();
BeanUtils.copyProperties(use,newUser);
System.out.println("赋制后的数据,姓名："+ newUser.getName() + " 年龄：" + newUser.getAge() );

赋制后的数据,姓名：jeremy 年龄：23

public static void copyProperties(Object source, Object target, String... ignoreProperties) throws BeansException {
        copyProperties(source, target, (Class)null, ignoreProperties);
    }

    public static String[] getNullPropertyNames (Object source) {
        final BeanWrapper src = new BeanWrapperImpl(source);
        PropertyDescriptor[] pds = src.getPropertyDescriptors();
        Set<String> emptyNames = new HashSet<String>();
        for(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);
    }

public static void main(String[] args) {
    User user1 = new User();
    user1.setName("jeremy");
    User user2 = new User();
    user2.setAge(23);
    User user3 = new User();
    BeanUtils.copyProperties(user1,user3);
    System.out.println("user1 赋值给 user3 数据，姓名:" + user3.getName() + " 年龄：" + user3.getAge());
    BeanUtils.copyProperties(user2,user3,getNullPropertyNames(user2));
    System.out.println("user2 赋值给 user3 数据，姓名:" + user3.getName() + " 年龄：" + user3.getAge());
}

user1 赋值给 user3 数据，姓名:jeremy 年龄：null
user2 赋值给 user3 数据，姓名:jeremy 年龄：23