（一）Spring Boot集成MyBatis快速入门

一、在IDEA中创建Spring Boot项目

二、添加依赖（把以下三个依赖都勾上）

 三、Maven POM

（把上面的依赖选中后，创建项目，打开pom.xml文件就可以看到以下代码，即添加成功）

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.6.7version>
        <relativePath/> 
    parent>
    <groupId>com.zhangguogroupId>
    <artifactId>mybatisdemo2artifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>mybatisdemo2name>
    <description>Demo project for Spring Bootdescription>
    <properties>
        <java.version>1.8java.version>
    properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>2.2.2version>
        dependency>

        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>

project>

四、创建数据库与表

create database mybatis

use mybatis

CREATE TABLE `category` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '类型编号',
  `name` varchar(64) NOT NULL COMMENT '类型名称',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=utf8;

INSERT into category values(1,'五金');
INSERT into category values(2,'数码');
INSERT into category values(3,'服饰');
INSERT into category values(4,'生鲜');
INSERT into category values(5,'书籍');
INSERT into category values(6,'珠宝');

select * from `category`

五、添加实体类

package com.zhangguo.mybatisdemo2.entity;

import java.io.Serializable;

public class Category implements Serializable {
    // 字段
    private int id;
    private String name;

    // 访问器
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
    //重写toString方法 
    @Override
    public String toString() {
        return "Category{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

六、定义数据访问接口

package com.zhangguo.restdemo.dao;

import com.zhangguo.restdemo.entity.Category;

import java.util.List;

public interface CategoryDao {
    List<Category> findAll();
}

七、定义sql映射文件

（在resources目录下创建一个mapper目录，专门用于存放sql映射文件，在目录中创建一个CategoryDao.xml文件，如下图所示：）

 CategoryDao.xml文件的内容如下：

<?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.fairy.mybatisdemo2.dao.UserDao">
    <select id="findById" resultType="User">
        select
               uid,
               uname,
               usex
        from userinfo
        where uid=#{uid}
    select>
mapper>

注意：

八、在application.yaml中定义配置文件

（application.yaml映射文件中主要包含了数据库连接信息与mybatis配置信息）

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/mybatis?serverTimezone=GMT&useUnicode=true&characterEncoding=utf-8

mybatis:
  type-aliases-package: com.fairy.mybatisdemo2.entity
  mapper-locations: classpath:/mapper/*.xml

注意：

 九、配置映射接口所在的包

（mybatisdemo2Application.java启动文件的内容如下）

package com.fairy.mybatisdemo2;

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

@SpringBootApplication
@MapperScan("com.fairy.mybatisdemo2.dao") // dao包路径
public class Mybatisdemo2Application {

    public static void main(String[] args) {
        SpringApplication.run(Mybatisdemo2Application.class, args);
    }

}

@MapperScan作用是指定要变成实现类的接口所在的包，然后包下面的所有接口在编译之后都会生成相应的实现类。

十、编写单元测试

package com.zhangguo.mybatisdemo2;

import com.zhangguo.mybatisdemo2.dao.CategoryDao;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class Mybatisdemo2ApplicationTests {

    @Autowired
    CategoryDao categoryDao;

    @Test
    void categoryDaoTest() {
        System.out.println(categoryDao.findAll());
    }

}

测试结果：