最终项目结构目录

创建项目

新建一个Spring项目

填写项目信息

选择添加的依赖

最后【Finish】完成

配置数据库源

在application.properties资源文件中添加mybatis的配置信息；项目启动时，会自动加载配置项。

根据情况更改内容(数据库名称，登陆账户及密码，locations等)：

#datasource
spring.datasource.tomcat.driver-class-name=com.mysql.jdbc.Driver

#mybatis
spring.datasource.url=jdbc:mysql://localhost:3306/new_schema?useUnicode=true&characterEncoding=UTF-8&transformedBitIsBoolean=true&autoReconnect=true&failOverReadOnly=false&allowMultiQueries=true&useSSL=false
spring.datasource.username=root
spring.datasource.password=0000
spring.datasource.tomcat.default-auto-commit=true

mybatis.typeAliasesPackage=com.example.springboot.demo.Mapper
mybatis.mapper-locations=classpath:mappers/*.xml

基于三层架构进行开发

数据库

resources文件夹（Resources Root）

基于mybatis，将SQL写入到.xml配置文件中，添加mappers映射，userMappers.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.springboot.demo.Mapper.UserMapper">

    <!--id对应接口中的方法，名字要一样，parameterType是方法的参数类型，
    resultType是查询返回的类型，需要注意的是，这里的SQL语句后面不能加分号，变量不能加引号-->
    <select id="getById" parameterType="int" resultType="com.example.springboot.demo.entity.User">
        select * from user where id = #{id}
    </select>

    <insert id="insert" parameterType="string">
        insert into user(name) values(#{name})
    </insert>

    <select id="getUsers"  resultType="com.example.springboot.demo.entity.User">
        select * from user order by #{id}
    </select>

    <update id="updateUser" parameterType="com.example.springboot.demo.entity.User">
        update user set name=#{name} where id = #{id}
    </update>
    <delete id="deleteAllUsers">
        delete from user
    </delete>
    <delete id="deleteUser" parameterType="int">
        delete from user where id = #{id}
    </delete>

</mapper>

java文件夹（Sources Root）

创建一个实体类User（entity文件夹下），用于接收数据的对象

package com.example.springboot.demo.entity;

public class User {
    private String name;
    private int id;

    public User(){}
    public User(int id,String name){
        this.id = id;
        this.name = name;
    }
    public String getName() {
        return name;
    }
    public int getId() {
        return id;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void setId(int id) {
        this.id = id;
    }
}

Mapper用于创建数据接口，UserMapper接口

package com.example.springboot.demo.Mapper;

import com.example.springboot.demo.entity.User;
import org.springframework.stereotype.Repository;
import java.util.List;

@Repository
public interface UserMapper {
    User getById(int id);
    public boolean insert(String name);
    public List<User> getUsers();
    public boolean updateUser(User user);
    public boolean deleteUser(int id);
    public boolean deleteAllUsers();
}

Service实现，UserService实现类。（很多教程中加了接口，但是我觉得我不需要就没有增加。）

package com.example.springboot.demo.service;

import com.example.springboot.demo.Mapper.UserMapper;
import com.example.springboot.demo.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;

    public User getById(int id){
        return userMapper.getById(id);
    }
}

Control（这里使用了Restful风格）

package com.example.springboot.demo.controller;

import com.example.springboot.demo.entity.User;
import com.example.springboot.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/index") //在类上使用RequestMapping，里面设置的value就是方法的父路径
public class Controller {

    @Autowired
    private UserService userService;

    @GetMapping("/hi")  //如果方法上的RequestMapping没有value，则此方法默认被父路径调用
    public String index(){
        return "hello spring boot";
    }
    @RequestMapping("/users/{userId}")
    public User getUser(@PathVariable("userId") int userId){
        User user = userService.getById(userId);
        return user;
    }
}

DemoApplication主开关

package com.example.springboot.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@MapperScan("com.example.springboot.demo.Mapper")
@EnableCaching
@ComponentScan (basePackages = {"com.example.springboot.demo.service","com.example.springboot.demo.Mapper","com.example.springboot.demo.controller"})
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

配置成功

不出意外的话，在浏览器中可以看到项目搭建成功了。
http://localhost:8080/index/hi

http://localhost:8080/index/users/2