SpringBoot整合Mybatis

SpringBoot整合Mybatis

1. 添加依赖
2. 添加配置文件（MySql Mybatis ）
3. 创建Mapper接口
4. 创建xml映射文件

添加依赖

 <!--引入数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!--springBoot数据库连接  -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
      <!--spring整合mybatis   -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.0</version>
        </dependency>

修改配置文件

server:
 port: 8090

spring:
 datasource:
   driver-class-name: com.mysql.cj.jdbc.Driver
   url: jdbc:mysql://127.0.0.1:3306/jt?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
   username: root
   password: root
   #如果数据库密码以数字0开头 则必须使用""号包裹
   #password: "01234"

#SpringBoot整合Mybatis配置
mybatis:
 type-aliases-package: com.jt.pojo
 mapper-locations: classpath:/mybatis/*.xml
 #开启驼峰映射
 configuration:
   map-underscore-to-camel-case: true

在Spring Boot中多环境配置文件名需要满足application-{profile}.yml的格式，其中{profile}对应你的环境标识，比如：
application-dev.yml：开发环境
application-test.yml：测试环境
application-prod.yml：生产环境
注：配置文件中的中文注释很有可能影响程序从而报错

创建Mapper接口

package com.demo.mapper;

import com.demo.pojo.User;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface UserMapper {
    List<User> getAll();
}

创建userService

package com.demo.service;

import com.demo.pojo.User;
import java.util.List;


public interface UserService {
    List<User> getAll();
}

创建UserServiceImpl

package com.demo.service;

import com.demo.mapper.UserMapper;
import com.demo.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService{
    @Autowired
    private UserMapper userMapper;
    @Override
    public List<User> getAll() {
        return userMapper.getAll() ;
    }
}

创建UserController

package com.demo.controller;

import com.demo.pojo.User;
import com.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    @RequestMapping("getAll")
    public List<User> getAll() {
        return userService.getAll();
    }
}

创建UserMapper.xml映射文件

<?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">
<!--规则: namespace必须与接口一一对应  -->
<mapper namespace="com.demo.mapper.UserMapper">

    <!--
        定义别名包: 添加了别名包之后可以简化resultType编辑.
    -->
    <select id="getAll" resultType="User">
        select * from demo_user
    </select>

    <!--驼峰命名规则
        表字段:  user_id,user_name
        对象的属性: userId,userName
        resultType: 保证属性与字段名称必须一致.
        Mybatis提供了驼峰命名规则:
        规则:  字段user_id~~~去除_线~~~之后映射对象的属性
        userId
    -->

</mapper>

编辑启动类

package com.demo.springmybatis;

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

@SpringBootApplication
@MapperScan("com.demo.mapper") //Spring内部为mybatis创建动态代理对象--JDK代理
public class SpringMybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringMybatisApplication.class, args);
    }

}

编辑测试类

package com.demo.springmybatis;

import com.demo.mapper.UserMapper;
import com.demo.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
public class SpringMybatisApplicationTests {
    @Autowired
    private UserMapper userMapper;

    @Test
    public void testGetAll(){
        System.out.println(userMapper.getClass());
        List<User> userList = userMapper.getAll();
        System.out.println(userList);
    }
}

测试结果

class com.sun.proxy.$Proxy71
2021-10-06 16:19:00.475  INFO 8980 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2021-10-06 16:19:00.767  INFO 8980 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
[User(id=1, name=lily, age=5, sex=女), User(id=2, name=mary, age=18, sex=女)]

成功获取表格中的所有信息！