springboot + mybatisPlus 入门实例 入门demo
使用mybatisPlus的优势
集成mybatisplus后，简单的CRUD就不用写了，如果没有特别的sql，就可以不用mapper的xml文件。
mybatisPlus官网： https://mp.baomidou.com/guide
项目搭建前提条件
1、IDEA，并且已安装lombok插件
2、mysql数据库，本实例采用mysql8.0版本，与mysql5.x版本有些不一样，如果使用mysql5.x，只需要修改相应的配置即可。
1. 导入相关依赖
如果项目中有mybatis依赖可以直接删除了，mybatisPlus里包含了mybatis的依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- mybatisPlus -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.3.2</version>
</dependency>
<!-- mysql 5.x驱动 -->
<!--<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.39</version>
</dependency>-->
<!-- mysql8.0 驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.20</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.21</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
2. yml 配置
server:
port: 8080
servlet:
context-path: /
tomcat:
uri-encoding: UTF-8
spring:
datasource:
# mysql5.x 配置，高版本需要加useSSL=false
#url: jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false
# mysql8.0 需要加&useSSL=false&serverTimezone=UTC
url: jdbc:mysql://localhost:3306/test?zeroDateTimeBehavior=convertToNull&characterEncoding=utf8&useSSL=false&serverTimezone=UTC
username: root
password: 123456
# mysql8.0 驱动
driver-class-name: com.mysql.cj.jdbc.Driver
# mysql5.x 驱动
#driver-class-name: com.mysql.jdbc.Driver
debug: false
#Druid#
name: test
type: com.alibaba.druid.pool.DruidDataSource
filters: stat
maxActive: 20
initialSize: 1
maxWait: 60000
minIdle: 1
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 20
#-----------------------------------------------------
# pom.xml引用 mybatis-plus包，需要这样配置
#mybatis:
# type-aliases-package: com.example.demo.model
# mapper-locations: classpath:mybatis/mappers/*.xml
# configuration:
# map-underscore-to-camel-case: true
#-----------------------------------------------------
#-----------------------------------------------------
# pom.xml引用 mybatis-plus-boot-starter包，需要这样配置
mybatis-plus:
type-aliases-package: com.example.demo.model
mapper-locations: classpath:mybatis/mappers/*.xml
configuration:
map-underscore-to-camel-case: true
#-----------------------------------------------------
3. 代码
User类
@TableId(type = IdType.AUTO) 表示我们使用自增主键
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;
import lombok.ToString;
import java.util.Date;
@Data
@ToString
@TableName("user_demo")
public class User {
@TableId(type = IdType.AUTO)
private Integer id;
@TableField("name")
private String name;
@TableField("password")
private String password;
@TableField("age")
private Integer age;
@TableField("email")
private String email;
/**
* 注意：此处如果不加 @TableField注解，mybatisPlus会默认将createTime映射成 create_time字段
* 由于数据库字段为createTime，所以需要指定
*/
@TableField("createTime")
private Date createTime;
}
mapper类
继承BaseMapper就可以，会把一些crud的操作帮我们自动生成注入。
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.demo.model.User;
public interface UserMapper extends BaseMapper<User> {
public User findUserByName(String name);
}
Controller类
import com.example.demo.mapper.UserMapper;
import com.example.demo.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserMapper userMapper;
/**
* 根据ID查找
* @param id
* @return
*/
@GetMapping("/get/{id}")
public String getUserById(@PathVariable String id){
User user = userMapper.selectById(id);
return "hello " + user.getName();
}
/**
* 根据name查找
* @param name
* @return
*/
@GetMapping("/name/{name}")
public String getUserByName(@PathVariable String name){
User user = userMapper.findUserByName(name);
return "getUserByName " + user.getName();
}
}
UserMapper.xml
<?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.example.demo.mapper.UserMapper">
<resultMap id="userResultMap" type="com.example.demo.model.User" >
<id column="id" property="id" />
<result column="name" property="name" />
<result column="password" property="password" />
<result column="age" property="age" />
<result column="email" property="email" />
<result column="createTime" property="createTime" />
</resultMap>
<select id="findUserByName" resultMap="userResultMap">
SELECT
id,
name,
password,
age,
email,
createTime
FROM user_demo
where name = #{name}
</select>
</mapper>
实例运行效果
浏览器输入：http://localhost:8080/user/name/aaa
实例运行效果
4. 写在最后
本实例源代码：https://gitee.com/jelly_oy/springboot-mybatisPlus-demo
本实例采用springboot2.3.3 + mybatis-plus3.3.2 + mysql8.0 进行搭建，如果使用mysql5.x，只需要修改相关配置即可。
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