使用SpringBoot集成Mybatis的详细

第一步：配置pom文件，配置mybatis和数据库相关依赖

这里mybatis采用的是3.4.5版本，注意：mybatis3.4.0版本以上才支持@Mapper注解

相关依赖代码如下：

<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>

<dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>

pom文件完整代码如下：

<?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 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>2.6.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-demo1</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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>
        <dependency>
            <groupId>org.xmlunit</groupId>
            <artifactId>xmlunit-core</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>7</source>
                    <target>7</target>
                </configuration>
            </plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>8</source><target>8</target></configuration></plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

导入pom文件后，若依赖报红，需要重新import下（点击下图里的刷新图标）

第二步：在项目里新建相关包，在对应包下添加如下文件

这边主要设计到的包有Controller(控制层)，Entity(实体层)，Service(接口层)，ServiceImpl(接口实现层)，Mapper(数据持久化层)

第三步：编写实体类，数据库建对应的表

在Entity包下编写student实体类，代码如下

package com.example.demo.Entity;


import lombok.Data;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

@Data
public class Student {
    private String id;
    private String name;
    private Integer age;
    private String sex;
    private String grade;

    public Student(String id,String name,Integer age,String sex,String grade)
    {
        this.id = id;
        this.name=name;
        this.age=age;
        this.sex=sex;
        this.grade=grade;
    }
}

数据库中新建一张学生表：

表中插入数据，用于后续接口验证

第四步： 在application.properties中配置数据库和mybatis相关属性

port指的是端口号，可以不用设置（这边设置是因为8080端口被占用）

数据库的名称、账号和密码修改成自己的即可

server.port=8081
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/stms?useUnicode=true&characterEncoding=UTF-8&useSSL=false
spring.datasource.username=root
spring.datasource.password=123456
mybatis.type-aliases-package=com.example.demo.Entity
mybatis.mapper-locations= classpath:com.example.demo.Mapper/*.xml

第五步：添加Mapper接口文件和对应xml文件

可以在启动类上添加@MapperScan注解，或者在mapper层的每个接口类上添加@Mapper注解@MapperScan注解作用：指定要变成实现类的接口所在的包，然后包下面的所有接口在编译之后都会生成相应的实现类

@MapperScan(basePackages = "com.example.demo.Mapper")

studentMapper接口类代码如下

package com.example.demo.Mapper;


import com.example.demo.Entity.Student;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface StudentMapper {
  List<Student> selectAll();
}

在resource下建立如下目录和文件

完整代码如下：

注意事项：namespace的值要和接口类的路径对应上，否则会报错

<?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.example.demo.Mapper.StudentMapper">

    <select id="selectAll"  resultType="com.example.demo.Entity.Student">
        select id,name,age,sex,grade
        from `student`
    </select>


</mapper>

第六步：编写Controller层

在Controller层的StudentController文件里编写测试代码，如下：

package com.example.demo.Controller;

import com.example.demo.DTO.ResultDto;
import com.example.demo.Entity.Student;
import com.example.demo.Mapper.StudentMapper;
import com.example.demo.Service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Repository;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

@RestController
@RequestMapping("/student")
public class StudentController {
    @Autowired
    private StudentService studentService;

    @Autowired
    private StudentMapper studentMapper;


    @GetMapping("/getAll")
    public String selectAll()
    {
        
        List<Student> students = studentMapper.selectAll();
        
        return students.toString();
    }
}

最后一步：在浏览器输入http://localhost:8081/student/getAll

出现如下数据，则证明集成成功 ：

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