浅入 Mybatis-plus

先导入得用到的依赖（pom.xml）

　　　　<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-annotation</artifactId>
            <version>3.5.1</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-core</artifactId>
            <version>3.5.1</version>
        </dependency>

 

 新建 interface 的java文件 并继承 BaseMapper

package com.run.fire.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.run.fire.pojo.Alarm;
import org.apache.ibatis.annotations.*;


import java.util.List;

@Mapper
public interface AlarmMapper extends BaseMapper<Appendable>{
    //添加
    @Insert("insert into alarm_table(alarm_placeid,alarm_pre,alarm_upre)values(#{alarm_placeid},#{alarm_pre},#{alarm_upre})")
    int insert(Alarm alarm);

    //查看所有
    @Select("SELECT * FROM alarm_table;")
    List<Alarm> findAll();

    int update(Alarm alarm);
    //删除
    @Delete("delete from alarm_table where alarmId=#{alarmId}")
    Integer deleteById(@Param("alarmId") Integer id);

    //分页查询
    @Select("SELECT * FROM alarm_table where alarm_pre like #{alarmName} LIMIT #{pageNum},#{pageSize}")
    List<Alarm> selectPage(Integer pageNum,Integer pageSize,String alarmName);
    //总条数
    @Select("SELECT COUNT(*) FROM alarm_table")
    Integer seleTotal(String alarmName);



}

 

service调用mapper 可以进行实现业务逻辑

package com.run.fire.service.impl;

import com.run.fire.mapper.AlarmMapper;
import com.run.fire.pojo.Alarm;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class AlarmService {

    @Autowired
    private AlarmMapper alarmMapper;

    //查所有
    public List<Alarm>findAll(){
            List<Alarm> all= alarmMapper.findAll();
            return all;
    }

    //修改
    public int save(Alarm alarm){
        if(alarm.getAlarmId() == null){//如果数据库中没有id 则表示 新增数据
           return alarmMapper.insert(alarm);
        }else {//如果数据库中有id 则表示 修改
           return alarmMapper.update(alarm);
        }
    }

    //删除
    public int deleteById(int id){
        return alarmMapper.deleteById(id);
    }

    //分页查询
    public List<Alarm> findPage(Integer pageNum, Integer pageSize,String alarmName) {
        return alarmMapper.selectPage(pageNum, pageSize,alarmName);
    }
    //查数据条
    public Integer seleTotal(String alarmName) {
       return alarmMapper.seleTotal(alarmName);
    }
}

 

yml配置

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/数据库名字?characterEncoding=utf-8
    username: 账号
    password: 密码
    driver-class-name: com.mysql.jdbc.Driver

mybatis:
  mapper-locations: classpath:mapper/*.xml
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

mvc:
  view:
      prefix: /templates/
      suffix: .html

server:
  port: 端口号 |个人使用的是8080

 

 

动态sql

在resources目录下新建mapper文件夹 并新建 .xml的文件 写入mapper

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="">

</mapper>

`

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.run.fire.mapper.AlarmMapper">

    <update id="update">
        update alarm_table
        <set>
            <if test="alarm_placeid !=null ">
                alarm_placeid =#{alarm_placeid},
            </if>

            <if test="alarm_pre !=null  ">
                alarm_pre = #{alarm_pre},
            </if>

            <if test="alarm_upre !=null ">
                alarm_upre = #{alarm_upre},
            </if>

            <if test="alarm_type !=null">
                alarm_type = #{alarm_type},
            </if>

            <if test="alarm_upre !=null">
                alarm_upre = #{alarm_upre},
            </if>

            <if test="alarm_case !=null">
                alarm_case = #{alarm_case},
            </if>

            <if test="alarm_grade !=null">
                alarm_grade = #{alarm_grade}
            </if>

        </set>
        <where>
            alarmId=#{alarmId}
        </where>
    </update>

</mapper>