SpringBoot学习（三）—————— 框架整合其他框架之三（Mybatis）

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前言

本篇记录的是我在学习SpringBoot过程中，引入Mybatis的学习经验。

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提示：以下是本篇文章正文内容，下面案例可供参考

一、整合Mybatis

SpringBoot官方没有提供整合Mybatis的启动器，但是 Mybatis官方. 自己实现了。 所以我们要自己手动控制其版本。对应的启动器坐标如下

		<dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>

二、使用方法

1.引入启动器

在POM文件中引入对应的启动器坐标，我的POM文件：
代码如下：

<?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>com.kaikeba</groupId>
    <artifactId>sb-mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.11.RELEASE</version>
    </parent>
    <properties>
        <mybatis-starter-version>2.1.4</mybatis-starter-version>
    </properties>

    <dependencies>
        <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>
        </dependency>

        <!-- spring官方没有提供 mybatis的启动器 mybatis官方自己实现了 所以要手动控制版本  -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>${mybatis-starter-version}</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.24</version>
        </dependency>
    </dependencies>

</project>

代码如下（示例）：

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
import warnings
warnings.filterwarnings('ignore')
import  ssl
ssl._create_default_https_context = ssl._create_unverified_context

2.实体类User.java

代码如下：

package com.kaikeba.entity;

import java.util.Date;

/**
 * @author sunyang
 * @date 2021/5/28 12:25
 */
public class User {
    private Integer id;
    private String UserName;
    private String password;
    private String name;
    private Integer age;
    private Integer sex;
    private Date birthday;
    private Date created;
    private Date updated;
    private String note;

    public Integer getId() {
        return id;
    }

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

    public String getUserName() {
        return UserName;
    }

    public void setUserName(String userName) {
        UserName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getSex() {
        return sex;
    }

    public void setSex(Integer sex) {
        this.sex = sex;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public Date getCreated() {
        return created;
    }

    public void setCreated(Date created) {
        this.created = created;
    }

    public Date getUpdated() {
        return updated;
    }

    public void setUpdated(Date updated) {
        this.updated = updated;
    }

    public String getNote() {
        return note;
    }

    public void setNote(String note) {
        this.note = note;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", UserName='" + UserName + '\'' +
                ", password='" + password + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex=" + sex +
                ", birthday=" + birthday +
                ", created=" + created +
                ", updated=" + updated +
                ", note='" + note + '\'' +
                '}';
    }
}

3 持久层Mapper文件

代码如下：

package com.kaikeba.mapper;

import com.kaikeba.entity.User;

import java.util.List;

/**
 * @author sunyang
 * @date 2021/5/28 13:10
 */
//@Mapper
// 若是不写@Mapper注解 就要在启动类上增加@MapperScan注解 扫描对应的Mapper接口
public interface UserMapper {
    List<User> findAll();
}

4 SQL语句

<?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.kaikeba.mapper.UserMapper">
    <select id="findAll" resultType="user">
        select * from tbs_user
    </select>
</mapper>

5 配置文件

	server.port=8080
	logging.level.com.kaikeba=debug
	
	# 数据库连接信息
	spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
	spring.datasource.url=jdbc:mysql://127.0.0.1:3306/springboot-jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT
	spring.datasource.username=root
	spring.datasource.password=root
	
	# 别名
	mybatis.type-aliases-package=com.kaikeba.entity
	# 映射配置文件
	mybatis.mapper-locations=com.kaikeba.mapper/*.xml

6 测试类

package com.kaikeba.mapper;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest {

    @Resource
    private UserMapper userMapper;

    @Test
    public void findAll() {
        userMapper.findAll().stream().forEach(user -> System.out.println(user));
    }
}

7 启动类

package com.kaikeba;

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

/**
 * @desc @MapperScan 扫描包，当Mapper接口上没有@Mapper接口时，
 *     可配置此注解，扫描全包
 * @author sunyang
 * @date 2021/5/28 13:13
 */
@SpringBootApplication
@MapperScan("com.kaikeba.mapper")
public class MybatisApplication {
    public static void main(String[] args) {
        SpringApplication.run(MybatisApplication.class);
    }
}

8 测试结果

9 PS

9.1 配置

在整合Mybatis的时候，要在application（properties/yml）配置文件中配置别名和映射配置文件的位置，否则可能会出错

9.2 Mapper接口扫描

有两种扫描Mapper接口的方式:
① 是在对应的Mapper接口上增加@Mapper注解，此时，springboot启动时，逐个扫描带有@Mapper注解的接口文件进行注册，

② 第二种方式，不在Mapper接口文件时增加@Mapper注解，而是在启动类上使用@MapperScan（“包路径”），扫描“包路径”下的所有接口文件，统一注册。
去除接口上的注解

启动器上增加注解