有时候,我们在数据库中会插入一些字段的值时固定的,比如性别字段,它的值固定只有2个,男或者女; 或者季节字段,只有春夏秋冬4种。有时候在Java类中会采用枚举类型来表达相应的数据库字段,比如如下数据表:
create table student( id int auto_increment comment '学生ID', name varchar(50), gender varchar(10), primary key(id));
枚举类定义如下:
package com.example.demo.dao; public enum Gender { FEMAIL("女"), MAIL("男"); private String sex; public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } Gender(String s){ this.sex=s; } }
实体类定义如下:
1 package com.example.demo.dao; 2 3 public class Student { 4 private int id; 5 private String name; 6 private Gender gender; 7 8 public int getId() { 9 return id; 10 } 11 12 public void setId(int id) { 13 this.id = id; 14 } 15 16 public String getName() { 17 return name; 18 } 19 20 public void setName(String name) { 21 this.name = name; 22 } 23 24 public Gender getGender() { 25 return gender; 26 } 27 28 public void setGender(Gender gender) { 29 this.gender = gender; 30 } 31 }