SpringBoot学习（5） —— SpringBoot框架集成MyBatis

一. 添加MyBatis依赖

在pom.xml中添加mybatis依赖和mysql驱动 

        
        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>2.2.2version>
        dependency>
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <scope>runtimescope>
        dependency>

二. 连接数据库

 在application.properties中添加以下信息：

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2B8
spring.datasource.username=root
spring.datasource.password=123456

注意：spring.datasource.url=jdbc:mysql://localhost:3306/springboot中springboot是数据库名称

三. 引入mapper接口的映射文件

 1. 在pom.xml中引入src/main/resouces目录下所有xml文件： 

     mapper接口的映射文件通常存放在src/main/resouces目录下

    <build>
        
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <includes>
                    <include>**/*.*include>
                includes>
            resource>
        resources>

 2.  在application.properties中添加以下信息来指定映射文件存放在resources目录下的那个包内

     通常自定义创建一个包，用于存放映射文件。（这里在resources目录下创建了一个mapper包）

mybatis.mapper-locations=classpath:mapper/*.xml

3. 添加日志

 在application.properties中添加以下信息：

mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

四. 创建实体类对象

创建数据库表所对应的实体类对象

package com.xdu.studyspringboot.pojo;
 
public class User {
    private Integer id;
    private String name;
    private Integer age;
 
    public Integer getId() {
        return id;
    }
 
    public void setId(Integer id) {
        this.id = id;
    }
 
    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;
    }
 
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

五. Dao层

1. 创建Mapper接口 

package com.xdu.studyspringboot.mapper;
 
import com.xdu.studyspringboot.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
 
@Mapper
public interface UserMapper {
    User selectById(@Param("id") Integer id);
}

2. 创建Mapper接口的映射文件

在src/main/resources/mapper目录下创建与Mapper接口同名的xml文件，即UserMapper.xml

"1.0" encoding="UTF-8" ?>
mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xdu.studyspringboot.mapper.UserMapper">  
 
    <select id="selectById" resultType="com.xdu.studyspringboot.pojo.User">  
        select * from user where id=#{id}   
    select>
 
mapper>

六. Service层

1. 创建Service接口

package com.xdu.studyspringboot.service;
 
import com.xdu.studyspringboot.pojo.User;
 
public interface UserService {
    User queryUserById(Integer id);
}

2. 实现Service接口

package com.xdu.studyspringboot.service.impl;
 
import com.xdu.studyspringboot.mapper.UserMapper;
import com.xdu.studyspringboot.pojo.User;
import com.xdu.studyspringboot.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
 
    @Override
    public User queryUserById(Integer id) {
        return userMapper.selectById(id);
    }
}

七. 测试

package com.xdu.studyspringboot.controller;
 
import com.xdu.studyspringboot.pojo.User;
import com.xdu.studyspringboot.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
 
@Controller
public class UserController {
    @Autowired
    private UserService userService;
 
    @RequestMapping("/user")
    @ResponseBody
    public String queryUser(){
        Integer id = 1;
        User user = userService.queryUserById(id);
        return user.toString();
    }
}