2. SpringBoot整合Mybatis

本章内容基于SpringBoot入门：https://www.cnblogs.com/forelim/p/15379580.html

SpringBoot整合Mybatis

1. 导入依赖

   <!-- mysql -->
   <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>8.0.26</version>
   </dependency>
   <!-- mybatis启动器 -->
   <dependency>
       <groupId>org.mybatis.spring.boot</groupId>
       <artifactId>mybatis-spring-boot-starter</artifactId>
       <version>2.1.3</version>
   </dependency>
   <!-- 测试 -->
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-test</artifactId>
   </dependency>
   <!-- 分页插件 -->
   <dependency>
       <groupId>com.github.pagehelper</groupId>
       <artifactId>pagehelper-spring-boot-starter</artifactId>
       <version>1.3.0</version>
   </dependency>
   

2. 加载配置 application.yml

   # 端口号
   server:
     port: 8080
   
   # 数据源
   spring:
     datasource:
       # 驱动
       driver-class-name: com.mysql.cj.jdbc.Driver
       # 路径
       url: jdbc:mysql://localhost:3306/demo?useSSL=false&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
       # 用户名
       username: root
       # 密码
       password: mysql
   
   # mybatis配置
   mybatis:
     configuration:
       # 日志
       log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
       # 下划线转驼峰
       map-underscore-to-camel-case: true
     # 别名包
     type-aliases-package: com.demo.entity
     # 映射文件位置
     mapper-locations: classpath:mapper/*.xml
   
   # 分页插件
   pagehelper:
     # 数据库
     helper-dialect: mysql
     # 合理化
     reasonable: true
     # 支持通过方法传递参数
     support-methods-arguments: true
     # 参数
     params: count==countSql
     # 传入0时显示全部数据
     page-size-zero: true
   

3. Entity & Mapper

   public class Demo {
       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;
       }
   
   }
   

   import com.demo.entity.Demo;
   import org.apache.ibatis.annotations.Mapper;
   
   import java.util.List;
   
   @Mapper
   // 如果mapper接口过多 可以在主启动类上加上@MapperScan("mapper接口包") 代替 @Mapper注解
   public interface DemoMapper {
       /**
        * 查询全部
        * @return 列表
        */
       List<Demo> list();
   }
   

   <?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.demo.mapper.DemoMapper">
       <select id="list" resultType="demo">
           select id, name, age
           from t_demo
       </select>
   </mapper>
   

4. 测试类

   import com.demo.entity.Demo;
   import com.github.pagehelper.PageHelper;
   import com.github.pagehelper.PageInfo;
   import org.junit.jupiter.api.Test;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.boot.test.context.SpringBootTest;
   
   import java.util.List;
   
   @SpringBootTest
   public class DemoMapperTest {
   
       /**
        * 自动织入mapper接口
        */
       @Autowired
       private DemoMapper demoMapper;
       @Test
       void list() {
           // 分页
           PageHelper.startPage(1,2);
           // 调用
           List<Demo> list = demoMapper.list();
           // 封装分页对象
           PageInfo<Demo> demoPageInfo = new PageInfo<>(list);
       }
   }
   

5. 成功!