package com.ada.data.entity;import java.io.Serializable;import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;@MappedSuperclass
public class NumEntity<NUM extends Number> implements Serializable {@Id@GeneratedValue(strategy = GenerationType.AUTO)private NUM id;public NUM getId() {return id;}public void setId(NUM id) {this.id = id;}@Overridepublic int hashCode() {final int prime = 31;int result = 1;result = prime * result + ((id == null) ? 0 : id.hashCode());return result;}@Overridepublic boolean equals(Object obj) {if (this == obj)return true;if (obj == null)return false;if (getClass() != obj.getClass())return false;NumEntity other = (NumEntity) obj;if (id == null) {if (other.id != null)return false;} else if (!id.equals(other.id))return false;return true;}}

package com.tongna.rest.apps;import com.ada.data.entity.NumEntity;public class A extends NumEntity<Long> {}

A a = new A();a.setId(1l);Class<?> ccc = a.getClass().getMethod("getId").getReturnType();System.out.println(ccc);System.out.println(a.getId().getClass());

java泛型不是计算运行时的数据类型。

所以在使用BeanUtils.copyProperties(source, result);的时候id不能拷贝。