springboot+mybatis+mysql入门

1.开发工具：IDEA,JDK1.8，MYSQL

1.创建工程File--->New--->Project，回车

2.选择Spring Initializr

3.点击next

4.选择依赖项

5.完成创建

6.准备建表语句，本次使用mysql,建表语句如下：

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) NOT NULL,
  `password` varchar(50) NOT NULL,
  `realname` varchar(32) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=latin1

7.看下刚才创建项目的依赖pom.xml

<?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>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.lym</groupId>
    <artifactId>springboot-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-demo</name>
    <description>Demo project for Spring Boot</description>

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

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.2</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

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

</project>

8.创建实体类，如下：

package com.lym.springbootdemo.entity;

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

import java.io.Serializable;

@Getter
@Setter
@ToString
public class User  implements Serializable {
    private Integer id;
    private String userName;
    private String passWord;
    private String realName;
}

9.创建mapper接口

package com.lym.springbootdemo.mapper;

import com.lym.springbootdemo.entity.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper {

    User Sel(int id);

    int deleteUserById(int id);

    int saveUser(User user);

    int updateUserById(User user);
}

10.创建service层接口

package com.lym.springbootdemo.service;

import com.lym.springbootdemo.entity.User;
import com.lym.springbootdemo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {
    @Autowired
    UserMapper userMapper;

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

    public int deleteUserById(int id){
        return userMapper.deleteUserById(id);
    }

    public int saveUser(User user){
        return userMapper.saveUser(user);
    }

    public int updateUserById(User user){
        return userMapper.updateUserById(user);
    }

}

11.创建controller

package com.lym.springbootdemo.controller;

import com.lym.springbootdemo.entity.User;
import com.lym.springbootdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

/**
* @Description:    用户类的controller类
* @Author:         lym
* @CreateDate:     2020/3/20 13:12
*/
@RestController
@RequestMapping("/testboot")
public class UserController {

    @Autowired
    private UserService userService;

    /**
     * 根据用户ID，查询用户
     * @param id
     * @return
     */
    @RequestMapping("getUser/{id}")
    public String getUser(@PathVariable int id){
        User user = userService.Sel(id);
        if(user !=null){
            return userService.Sel(id).toString();
        }else{
            return null;
        }
    }
    /**
     * 删除用户
     * @param id
     * @return
     */
    @RequestMapping("deleteUserById/{id}")
    //@PathVariable   spring3.0后新增的功能，接收请求路径中的占位符的值。即，可以将URL中占位符参数{xxx},如题中的{id}，绑定到处理器类的方法形参中@PathVariable(“xxx“)
    public int deleteUserById(@PathVariable int id){
        return userService.deleteUserById(id);
    }

    /**
     * 增加用户
     * @param user
     * @return
     */
    @RequestMapping(value="/saveUser",method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
    public int saveUser(@RequestBody(required = false)  User user){
        return userService.saveUser(user);
    }
}

12.修改启动类，增加扫描注解

package com.lym.springbootdemo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@MapperScan("com.lym.springbootdemo.mapper")  //扫描的mapper
@SpringBootApplication
public class SpringbootDemoApplication {

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

}

13.准备编写配置文件application.yml

spring:
  profiles:
    active: dev

14.编写application-dev.ym

server:
  port: 8080
spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  mapper-locations: classpath:mapping/*.xml
  type-aliases-package: com.lym.springbootdemo.entity

#showSql
logging:
  level:
    com:
      lym:
        springbootdemo:
          mapper: debug

15.最后完成mapper SQL文件的编写

<?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.lym.springbootdemo.mapper.UserMapper">

    <resultMap id="BaseResultMap" type="com.lym.springbootdemo.entity.User">
        <result column="id" jdbcType="INTEGER" property="id" />
        <result column="userName" jdbcType="VARCHAR" property="userName" />
        <result column="passWord" jdbcType="VARCHAR" property="passWord" />
        <result column="realName" jdbcType="VARCHAR" property="realName" />
    </resultMap>
    <insert id="saveUser" parameterType="com.lym.springbootdemo.entity.User">
        insert into user (username,password,realname) values (#{userName},#{passWord},#{realName})
    </insert>
    <update id="updateUserById" parameterType="com.lym.springbootdemo.entity.User">
        update user set name=#{userName} where id = #{id}
    </update>
    <delete id="deleteUserById" parameterType="int">
        delete  from user where id=#{id}
    </delete>

    <select id="Sel" resultType="com.lym.springbootdemo.entity.User">
        select * from user where id = #{id}
    </select>
</mapper>

16.根据建表语句，完成数据库的创建。

17.自测阶段

18.经过测试，符合预期结果，可以完成数据的查询，删除，保存操作

19.以上是框架的搭建过程。小白初次练习，如有问题，烦请指正。