mybaits-plus学习笔记整合

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文章目录

准备工作

创建数据库

创建数据库以及表

创建数据库并设置字符集为utf-8:

CREATE DATABASE `mp` CHARACTER SET 'utf8' COLLATE 'utf8_general_ci';

创建表和测试数据:

--
-- 表的结构 `tb_user`
--

CREATE TABLE IF NOT EXISTS `tb_user` (
  `id` bigint(20) NOT NULL COMMENT '主键ID',
  `user_name` varchar(20) NOT NULL COMMENT '用户名',
  `password` varchar(20) NOT NULL COMMENT '密码',
  `name` varchar(30) DEFAULT NULL COMMENT '姓名',
  `age` int(11) DEFAULT NULL COMMENT '年龄',
  `email` varchar(50) DEFAULT NULL COMMENT '邮箱',
  `birthday` datetime DEFAULT NULL
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

--
-- 表中的数据 `tb_user`
--

INSERT INTO `tb_user` (`id`, `user_name`, `password`, `name`, `age`, `email`, `birthday`) VALUES
(1, 'zhangsan', '123456', '张三', 18, 'test1@yyl.cn', '2022-03-09 00:00:00'),
(2, 'lisi', '123456', '李四', 20, 'test2@yyl.cn', '2022-03-09 00:00:00'),
(3, 'wangwu', '123456', '王五', 28, 'test3@yyl.cn', '2022-03-09 00:00:00'),
(4, 'zhaoliu', '123456', '赵六', 21, 'test4@yyl.cn', '2022-03-09 00:00:00'),
(5, 'sunqi', '123456', '孙七', 24, 'test5@yyl.cn', '2022-03-09 00:00:00');

工程搭建

工程结构

创建工程

创建maven工程,分别填写GroupId ArtifactId和Version,如下:

<groupId>cn.yyl.mp</groupId>
<artifactId>yyl-mp-springboot</artifactId>
<version>1.0-SNAPSHOT</version>

导入依赖

导入maven依赖,由于本例采用Spring boot技术,使用mybatis-plus-boot-starter能与其便捷集成: 版本规划:

Spring boot: 2.1.3.RELEASE 
mybatis-plus: 3.1.0

pom文件如下:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!--简化代码的工具包-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--mybatis-plus的springboot支持-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.1.0</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
    </dependencies>

</project>

编写application.properties

spring.application.name = yyl-mp-springboot

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/mp?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&useSSL=false
spring.datasource.username=root
spring.datasource.password=root

# Logger Config
logging.level.root: debug

编写pojo

package cn.yyl.mp.pojo;

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.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

import java.time.LocalDateTime;

/**
 * @author Administrator
 * @version 1.0
 **/
@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
@TableName("tb_user")
public class User 
    @TableId(value = "id",type= IdType.ID_WORKER)//指定主键的字段名
    private Long id;

    @TableField("user_name")//指定对应字段名
    private String userName;
	@TableField("PASSWORD")
    private String password;
    @TableField("NAME")
    private String name;
    @TableField("AGE")
    private Integer age;
    @TableField("EMAIL")
    private String email;
    @TableField("BIRTHDAY")
    private LocalDateTime birthday;

注解说明:

lomlok:
	@Data:lombok的注解,使用它可以省略getter/setter方法。 
	@NoArgsConstructor: 生成无参构造 方法 
	@AllArgsConstructor:生成所有参数构造 方法,参数顺序与属性定义顺序一致。 
mybaits-plus:
	@TableName:指定表名
	@TableId:指定主键名
	@TableField:指定列名

编写mapper

package cn.yyl.mp.mapper;

import cn.yyl.mp.pojo.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;

/**
 * Created by Administrator.
 */
public interface UserMapper extends BaseMapper<User> 

该mapper类继承mybatisplus中的BaseMapper类

BaseMapper类中有一些常用的数据库查询方法,使用Base类之外的查询方法可以自己手动配置xml实现:

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package com.baomidou.mybatisplus.core.mapper;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;

public interface BaseMapper<T> 
    int insert(T entity);

    int deleteById(Serializable id);

    int deleteByMap(@Param("cm") Map<String, Object> columnMap);

    int delete(@Param("ew") Wrapper<T> wrapper);

    int deleteBatchIds(@Param("coll") Collection<? extends Serializable> idList);

    int updateById(@Param("et") T entity);

    int update(@Param("et") T entity, @Param("ew") Wrapper<T> updateWrapper);

    T selectById(Serializable id);

    List<T> selectBatchIds(@Param("coll") Collection<? extends Serializable> idList);

    List<T> selectByMap(@Param("cm") Map<String, Object> columnMap);

    T selectOne(@Param("ew") Wrapper<T> queryWrapper);

    Integer selectCount(@Param("ew") Wrapper<T> queryWrapper);

    List<T> selectList(@Param("ew") Wrapper<T> queryWrapper);

    List<Map<String, Object>> selectMaps(@Param("ew") Wrapper<T> queryWrapper);

    List<Object> selectObjs(@Param("ew") Wrapper<T> queryWrapper);

    IPage<T> selectPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);

    IPage<Map<String, Object>> selectMapsPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);


编写启动类

package cn.yyl.mp;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * @author Administrator
 * @version 1.0
 **/
@SpringBootApplication
@MapperScan("cn.yyl.mp.mapper")	 //设置mapper接口的扫描包
public class MyApplication 
    public static void main(String[] args) 
        SpringApplication.run(MyApplication.class,args);
    

注解说明:

@SpringBootApplication springboot启动入口标识
@MapperScan("cn.yyl.mp.mapper") mapper接口的扫描包

测试

编写测试用例

编写UserMapper的测试用例 ,使用UserMapper查询用户列表。

在test下创建测试类,包名为 cn.yyl.mp。

package cn.itcast.mp;

import cn.itcast.mp.mapper.UserMapper;
import cn.itcast.mp.pojo.User;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Arrays;
import java.util.List;

/**
 * @author Administrator
 * @version 1.0
 **/
@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest 

    @Autowired
    UserMapper userMapper;
    x
    @Test
    public void testSelect()
        //查询tb_user记录
        List<User> users = userMapper.selectList(null);
        System.out.println(users.toString());
    

运行测试

[
 User(id=1, userName=zhangsan, password=123456, name=张三, age=18, email=test1@itcast.cn, birthday=2022-03-09T00:00),
 User(id=2, userName=lisi, password=123456, name=李四, age=20, email=test2@itcast以上是关于mybaits-plus学习笔记整合的主要内容,如果未能解决你的问题,请参考以下文章

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