MyBatisPlus-------id生成策略

不同的表对应不同的id生成策略

日志：自增

购物订单：特殊规则（FQ23324AK443）

外卖单：关联地区日期等信息（　10 04 20200314 34 91）

关系表：可省略id

．．．．．．．．．．

＠TableId  :模型类中用于表示主键的属性定义上方---用来设置当前类中主键属性的生成策略

(1)   id自增：@TableId(type = IdType.AUTO)

package com.itheima.domain;


import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName("tbl_user")
public class User {
    
    @TableId(type = IdType.AUTO)
    private Long id;
    private String name;
    @TableField(value = "pwd", select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;
}

（２）存储数据时必须自己指定id，在数据库表中关闭id自增功能，在id上添加：@TableId(type = IdType.INPUT)

package com.itheima.domain;


import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName("tbl_user")
public class User {

    @TableId(type = IdType.INPUT)
    private Long id;
    private String name;
    @TableField(value = "pwd", select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;
}

（3）雪花算法生成id，在id上添加：@TableId(type = IdType.ASSIGN_ID)

package com.itheima.domain;


import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName("tbl_user")
public class User {

    @TableId(type = IdType.ASSIGN_ID)
    private Long id;
    private String name;
    @TableField(value = "pwd", select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;
}

若要所有得实体类id都用同一个策略生成，可在配置文件中设置好相应的格式，不必每个类的id属性都添加字段控制

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatisplus_db?serverTimezone=UTC
    username: root
    password: 130740
    type: com.alibaba.druid.pool.DruidDataSource
  main:
    banner-mode: off

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  global-config:
    banner: false
    db-config:
      id-type: assign_id

实体类名与表明不同也可通过全局配置

package com.itheima.domain;


import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
//@TableName("tbl_user")
public class User {

//    @TableId(type = IdType.ASSIGN_ID)
    private Long id;
    private String name;
    @TableField(value = "pwd", select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;
}

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatisplus_db?serverTimezone=UTC
    username: root
    password: 130740
    type: com.alibaba.druid.pool.DruidDataSource
  main:
    banner-mode: off

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  global-config:
    banner: false
    db-config:
      id-type: assign_id
      table-prefix: tbl_