21. Spring Boot 整合 MyBatis

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21.1 需求说明/图解

1. 将 Spring Boot 和 MyBatis 整合
2. 查询出一条数据

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21.2 综合案例

21.2.1 代码+配置实现

21.2.1.1 创建数据库和表

CREATE DATABASE `springboot_mybatis` 

USE `springboot_mybatis` 

CREATE TABLE `monster` (
`id` INT NOT NULL AUTO_INCREMENT, 
`age` INT NOT NULL, 
`birthday` DATE DEFAULT NULL, 
`email` VARCHAR(255) DEFAULT NULL, 
`gender` CHAR(1) DEFAULT NULL, 
`name` VARCHAR(255) DEFAULT NULL, 
`salary` DOUBLE NOT NULL,
PRIMARY KEY (`id`)
) CHARSET=utf8

SELECT * FROM `monster`

INSERT INTO monster VALUES(NULL, 20, '2000-11-11', 'nmw@sohu.com', '男', '牛魔王', 5000.88);
INSERT INTO monster VALUES(NULL, 10, '2011-11-11', 'bgj@sohu.com', '女', '白骨精', 8000.88);
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21.2.1.2 创建 springboot-mybatis 项目，使用灵活的方式创建 maven

• pom.xml 需要引入相关依赖

<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>4.0.0modelVersion>

    <groupId>com.xjsgroupId>
    <artifactId>springboot-mybatisartifactId>
    <version>1.0-SNAPSHOTversion>

    
    <parent>
        <artifactId>spring-boot-starter-parentartifactId>
        <groupId>org.springframework.bootgroupId>
        <version>2.5.3version>
    parent>

    
    <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-configuration-processorartifactId>
        dependency>

        
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
        dependency>

        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
        dependency>

    dependencies>

project>
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21.2.1.3 创建 resources/application.yml ， 配置数据源参数，并完成 Spring Boot 项目启动测试

server:
  port: 9090
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springboot_mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8
    username: root
    password: hsp
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21.2.1.4 切换数据源为 druid

• 修改 pom.xml (引入 druid依赖 )
• 并加入配置文件 com/xjs/springboot/mybatis/config/DruidDataSourceConfig.java
• 完成测试

<dependency>
    <groupId>com.alibabagroupId>
    <artifactId>druidartifactId>
    <version>1.1.17version>
dependency>
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package com.xjs.springboot.mybatis.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

/**
 * @Author: 谢家升
 * @Version: 1.0
 */
@Configuration
public class DruidDataSourceConfig {

    //编写方法，注入DruidDataSource
    @ConfigurationProperties("spring.datasource")
    @Bean
    public DataSource dataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        return druidDataSource;

    }

}

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21.2.1.5 bean

• 创建 com/xjs/springboot/mybatis/bean/Monster.java
• 回顾一下 mybatis 和 ssm项目整合

package com.xjs.springboot.mybatis.bean;

import lombok.Data;

import java.util.Date;

/**
 * @Author: 谢家升
 * @Version: 1.0
 */
@Data
public class Monster {
    private Integer id;
    private Integer age;
    private Date birthday;
    private String email;
    private String name;
    private String gender;
    private Double salary;
}

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21.2.1.6 mapper 接口

• 创建 com/xjs/springboot/mybatis/mapper/MonsterMapper.java

package com.xjs.springboot.mybatis.mapper;

import com.xjs.springboot.mybatis.bean.Monster;
import org.apache.ibatis.annotations.Mapper;

/**
 * @Author: 谢家升
 * @Version: 1.0
 *
 * 在Mapper接口使用 @Mapper 就会扫描，并将Mapper接口对象注入
 */
@Mapper
public interface MonsterMapper {

    //编写方法，根据 id 返回 Monster对象
    public Monster getMonsterById(Integer id);

}

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21.2.1.7 Mapper.xml 文件

• 创建 src/main/resources/mapper/MonsterMapper.xml
• 文件模板从 mybatis 官方文档拷贝

DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.xjs.springboot.mybatis.mapper.MonsterMapper">

    
    <select id="getMonsterById" resultType="Monster">
        SELECT * FROM `monster` WHERE id=#{id}
    select>

mapper>
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21.2.1.8 创建 service 层

• 创建 com/xjs/springboot/mybatis/service/MonsterService.java

package com.xjs.springboot.mybatis.service;

import com.xjs.springboot.mybatis.bean.Monster;

/**
 * @Author: 谢家升
 * @Version: 1.0
 */
public interface MonsterService {

    //根据 id 返回 Monster对象
    public Monster getMonsterById(Integer id);

}

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• 创建 com/xjs/springboot/mybatis/service/impl/MonsterServiceImpl.java

package com.xjs.springboot.mybatis.service.impl;

import com.xjs.springboot.mybatis.bean.Monster;
import com.xjs.springboot.mybatis.mapper.MonsterMapper;
import com.xjs.springboot.mybatis.service.MonsterService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * @Author: 谢家升
 * @Version: 1.0
 */
@Service
public class MonsterServiceImpl implements MonsterService {

    //装配MonsterMapper
    @Resource
    private MonsterMapper monsterMapper;

    @Override
    public Monster getMonsterById(Integer id) {
        return monsterMapper.getMonsterById(id);
    }
}

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21.2.1.9 Controller

• 创建 com/xjs/springboot/mybatis/controller/MonsterController.java

package com.xjs.springboot.mybatis.controller;

import com.xjs.springboot.mybatis.bean.Monster;
import com.xjs.springboot.mybatis.service.MonsterService;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.annotation.Resource;

/**
 * @Author: 谢家升
 * @Version: 1.0
 */
@Controller
public class MonsterController {

    //装配MonsterService
    @Resource
    private MonsterService monsterService;

    @GetMapping("/monster")
    @ResponseBody
    public Monster getMonsterById(@RequestParam(value = "id") Integer id) {

        Monster monster = monsterService.getMonsterById(id);
        return monster;
    }

}

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21.2.1. 10 修改 resources/application.yml ，指定 mybatis 的配置参数

server:
  port: 9090
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springboot_mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8
    username: root
    password: hsp

mybatis:
  #指定要扫描的 XxxMapper.xml文件
  mapper-locations: classpath:mapper/*.xml

  #方式一
  #通过 config-location 可以指定 mybatis-config.xml文件，可以以传统的方式来配置mybatis
#  config-location: classpath:mybatis-config.xml

  #方式二
  #我们也可以直接在 application.yml 进行配置
  #举例说明：
  #1.比如配置原来的 类型别名- typeAliases
  #2.配置输出底层的原生sql (标准日志输出)
  #3.还有其他配置，用到再说...
  type-aliases-package: com.xjs.springboot.mybatis.bean
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

  #说明：配置mybatis的两种方式的选择：
  #如果配置比较简单，就直接在 application.yml文件中配置即可
  #如果配置内容比较多，也可以单独的做一个 application.yml 进行配置
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21.2.2 测试页面效果

• 完成测试
• 浏览器: http://localhost:9090/monster?id=1

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21.3 注意事项和细节说明(解决时区问题)

1. spring boot 整合 mybatis 取出的日期，出现 8 小时时差 解决方案

package com.xjs.springboot.mybatis.bean;

import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.Data;

import java.util.Date;

/**
 * @Author: 谢家升
 * @Version: 1.0
 */
@Data
public class Monster {
    private Integer id;
    private Integer age;
    //通过注解来解决时区问题
    //GMT 就是格林尼治标准时间
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private Date birthday;
    private String email;
    private String name;
    private String gender;
    private Double salary;
}

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• 完成测试

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