泛型父类中获取子类的泛型，延伸工具类

小灰灰 2022-09-01 08:30 253阅读 0赞

接口：

public interface Convertable<T,R> extends Serializable {
        /**
         * 转换为R对象
         */
        R convertTo() throws Exception;
    
        /**
         * T对象赋值
         */
        void convertFor(R r) throws Exception;
    }

接口实现：

public abstract class ConvertableImpl<T, R> implements Convertable<T, R> {
        /**
         * 将R转换为T类型
         */
        @Override
        public R convertTo() throws Exception {
            Class<R> classR = null;
            Type genericSuperclass = this.getClass().getGenericSuperclass();
            if (genericSuperclass instanceof ParameterizedType) {
                ParameterizedType parameterizedType = (ParameterizedType) genericSuperclass;
                // size=2，第一个是T，第二个是R
                Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
                classR = (Class<R>) actualTypeArguments[1];
            }
            R r = classR.newInstance();
            BeanUtils.copyProperties(this, r);
            return r;
        }
        /**
         * T对象赋值
         */
        @Override
        public void convertFor(R r) throws Exception {
            BeanUtils.copyProperties(r, this);
        }
    }

DTO：

@Data
    public class UserDto extends ConvertableImpl<UserDto, UserPo> {
        private String id;
        private String username;
        private String password;
        private String name;
        private String phone;
    }

DO：

@Data
    public class UserPo extends ConvertableImpl<UserPo, UserVo> {
        private String id;
        private String username;
        private String password;
        private String name;
        private String phone;
        private Date createTime;
        private Date updateTime;
        private boolean enable;
    }

VO：

@Data
    public class UserVo {
        private String id;
        private String username;
        private String name;
        private String phone;
    }

测试代码：

/**
         * 假设一个正常接口保存流程
         * @param args
         */
        public static void main(String[] args) throws Exception {
            // 1、接口进来的入参
            UserDto dto = new UserDto();
            dto.setName("小明");
            dto.setPhone("12312312313");
            dto.setUsername("xiaoming");
            dto.setPassword("123456");
            // 2、DTO ==》DO
            UserPo po = dto.convertTo();
            po.setCreateTime(new Date());
            po.setUpdateTime(new Date());
            // 3、save po保存成功，回写ID""
            po.setId("1");
            // 4、PO ==》VO
            UserVo vo = po.convertTo();
            System.out.println(vo.getId());
        }