一、介绍
MyBatis 是一款优秀的持久层框架，它支持定制化SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息，将接口和 Java 的 POJOs(Plain Ordinary Java Object,普通的 Java对象)映射成数据库中的记录。
二、springboot中集成Mybatis所需的特有的相关依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.6</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
三、相关配置文件
- application.yml文件配置
mybatis:
mapper-locations: classpath:mybatis/mapper/*.xml #配置xml映射文件的目录
config-location: classpath:mybatis/mybatis-config.xml #mybatis配置文件
spring:
datasource:
username: root
password:
url: jdbc:mysql://localhost:3306/sy_java_db?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8 #jdbc数据库连接固定写法
driver-class-name: com.mysql.cj.jdbc.Driver #对应使用的驱动
- mybatis-config.xml文件配置
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="mysql">
<!--配置Mysql的环境-->
<environment id="mysql">
<!--配置事务的类型-->
<transactionManager type="JDBC"/>
<!--配置数据源(连接池)-->
<dataSource type="POOLED">
<!--配置连接数据库的四个基本信息-->
<property name="driver" value="com.mysql.cj.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/sy_java_db" />
<property name="username" value="root" />
<property name="password" value="" />
</dataSource>
</environment>
</environments>
<mappers>
<!--被扫描的配置xml-->
<mapper resource="mapper/UserDao.xml" />
</mappers>
</configuration>
- 简单的Mapper xml配置样例
<?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.song.dao.UserDao"> <!--接口，定义操作数据的方法-->
<resultMap type="com.song.entity.User" id="UserMap"> <!--实体类，类中属性对应所需查询的表的字段，这里包名使用entity，也可以是pojo-->
<result property="userId" column="user_id" jdbcType="INTEGER"/> <!--实体类与表字段的映射关系，字段的数据类型-->
<result property="name" column="name" jdbcType="VARCHAR"/>
<result property="age" column="age" jdbcType="INTEGER"/>
</resultMap>
<!--query single-->
<select id="queryById" resultMap="UserMap">
select
user_id, `name`, age
from sy_java_db.user
where user_id = #{userId}
</select>
<!--query by id-->
<select id="queryAll" resultMap="UserMap">
select
user_id, `name`, age
from sy_java_db.user
</select>
</mapper>
四、Java相关代码
- UserDao.java
UserDao接口，方法名与对应mapper的xml文件中的select/insert/delete/update标签中的id的值一致
package com.song.dao;
import com.song.entity.User;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
@Mapper //用以申明接口是Mapper接口，会自动被扫描
public interface UserDao {
User queryById(int userId);
List<User> queryAll();
}
- User.java 实体类编写
package com.song.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User implements Serializable {
private static final long serialVersionUID = -81805678943456282L;
private int userId;
private String name;
private int age;
}
测试
- 创建Get请求传输userId获取用户名
package com.song.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.song.constant.MsgCode;
import com.song.dao.UserDao;
import com.song.entity.User;
import com.song.response.BaseResponse;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
@RestController
public class HomeController {
@Resource
private UserDao userDao;
@Resource
ObjectMapper objectMapper;
@GetMapping("/getUserInfo")
public Object home(HttpServletRequest request){
int userId = Integer.parseInt(request.getParameter("userId"));
User users = userDao.queryById(userId);
String s;
try {
s = objectMapper.writeValueAsString(users);
} catch (JsonProcessingException e) {
return BaseResponse.fail(MsgCode.REQUEST_FAIL_OTHER_ERR.getCode(),MsgCode.REQUEST_FAIL_OTHER_ERR.getMessage());
}
return BaseResponse.ok(s);
}
}
-
启动SpringBoot
-
使用postman进行测试
