作者简介

作者名：编程界明世隐
简介：CSDN博客专家，从事软件开发多年，精通Java、JavaScript，博主也是从零开始一步步把学习成长、深知学习和积累的重要性，喜欢跟广大ADC一起打野升级，欢迎您关注，期待与您一起学习、成长、起飞！

引言

我本来是一直用eclipse和myeclipse的老程序员了，很多我的粉丝小伙伴都说他们要用idea，问我怎么不用idea，其实明哥觉得用啥开发工具都不是重点，重点是要跟着明哥多学Java知识、多练习，但是作为一个宠粉的人，我怎么能拒绝粉丝的要求呢，于是我偷偷的去学习了一波（拿来吧你），然后就写了这个系列，希望小伙伴们能有所收获，明哥会努力更新的。

步骤

创建springboot项目

参考我之前的文章：IDEA中创建springboot项目

添加依赖

我这里把完整的全部贴出来

<?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>

    <groupId>org.demo</groupId>
    <artifactId>demo02</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencies>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
        </dependency>
        <!--druid连接池--><dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.0.29</version>
    </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.18</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

创建实体类
这里用了lombok插件，如果需要学习这个插件就看上一篇文章

import lombok.Data;

@Data
public class User {
    
    
    private int id;
    private String name;
    private String pwd;
}

创建接口

import com.demo.vo.User;
import java.util.List;
public interface UserMapper {
    
    
    public List<User> selectUser();
}

创建接口配置文件 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.demo.mapper.UserMapper">
    <!--id对应UserDAO接口方法名-->
    <!--parameterType对应参数类型-->
    <!--resultType对应返回值类型-->
    <!--注意sql语句字段和数据库对应-->
    <select id="selectUser" resultType="com.demo.vo.User">
        SELECT * FROM user
    </select>
</mapper>

核心配置文件application.yml

server:
  port: 8080
  servlet:
    context-path:

spring:
  # 配置文件选择(dev，pro)
  profiles:
    　active: dev

  # 国际化（消息源自动配置,springboot默认找出messages）
  messages:
    basename: i18n.messages
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/mysql_test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource

mybatis:
  #  mapper文件
  mapper-locations: mapper/*Mapper.xml
  #  实体类
  type-aliases-package: com.demo.*.vo

UserService类

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

import java.util.List;

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

    public List<User> selectUser() {
    
    
        return userMapper.selectUser();
    }
}

启动类DemoApplication

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

@SpringBootApplication
@MapperScan("com.demo.mapper")
public class DemoApplication {
    
    
    public static void main(String[] args) {
    
    
        SpringApplication.run(DemoApplication.class, args);
    }
}

控制类UserController

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

import java.util.List;

@RestController
@RequestMapping("/test")
public class UserController {
    
    

    @Autowired(required = false)
    private UserService userService;

    @GetMapping("/query")
    public  String query(){
    
    
        String result="";
        List<User> usersList = userService.selectUser();
        for (User user : usersList) {
    
    
            result +=user.toString();
        }
        return result;
    }
}