文章目录
数据库表
CREATE TABLE `mall_category` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT '类别Id',
`parent_id` int(11) DEFAULT NULL COMMENT '父类别id当id=0时说明是根节点,一级类别',
`name` varchar(50) DEFAULT NULL COMMENT '类别名称',
`status` tinyint(1) DEFAULT '1' COMMENT '类别状态1-正常,2-已废弃',
`sort_order` int(4) DEFAULT NULL COMMENT '排序编号,同类展示顺序,数值相等则自然排序',
`create_time` datetime DEFAULT NULL COMMENT '创建时间',
`update_time` datetime DEFAULT NULL COMMENT '更新时间',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=100031 DEFAULT CHARSET=utf8
1 引入依赖
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
2 编写yml文件
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: 123456
url: jdbc:mysql://127.0.0.1:3306/mall?characterEncoding=utf-8&useSSL=false
3别写实体类：Category
package com.example.mybaits.domain;
import java.util.Date;
public class Category {
private Integer id;
private Integer parentId;
private String name;
private Boolean status;
private Integer sortOrder;
private Date createTime;
private Date updateTime;
}
4使用
4.1 注解方式
4.1.1 编写dao层
package com.example.mybaits.dao;
import com.example.mybaits.domain.Category;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
@Mapper
public interface CategoryMapper {
@Select("select * from mall_category where id =#{id}")
Category findOne(@Param("id") Integer id);
}
4.1.1 测试
右键CategoryMapper----》Go to—>>Test 即可创建test
注意：
1 引入的包
import org.junit.Test;
import org.junit.runner.RunWith;
2 @test 的方法都是void
package com.example.mybaits.dao;
import com.example.mybaits.domain.Category;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.junit.runner.RunWith;
@RunWith(SpringRunner.class)
@SpringBootTest
public class CategoryMapperTest {
@Autowired
private CategoryMapper categoryMapper;
@Test
public void findOne() {
Category one = categoryMapper.findOne(100001);
System.out.print(one.toString());
}
}
4.1.1.1 注意1
数据库中 parent_id 为0 没有显示
而实体类时 parentId 不匹配，所以修改yml文件
mybatis:
configuration:
map-underscore-to-camel-case: true
此时返回的结果：
4.1.1.1 注意2
每一个dao层都写@mapper 过于麻烦
可以dao层不写，在启动类上配置一个即可
@MapperScan(basePackages = “com.example.mybaits.dao”)
package com.imooc.mall;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan(basePackages = "com.example.mybaits.dao")
public class MallApplication {
public static void main(String[] args) {
SpringApplication.run(MallApplication.class, args);
}
}
4.2 xml方式
4.2.1 编写dao层
public interface CategoryMapper {
Category queryByid(Integer id);
}
4.2.2编写xml
在resource 下创建mapper目录：创建CategoryMapper.xml
<?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.mybaits.dao.CategoryMapper">
<select id="queryByid" resultType="com.example.mybaits.domain.Category">
select * from mall_category where id = #{id}
</select>
</mapper>
4.2.3修改yml
mapper-locations: classpath:mapper/*.xml
若想让 mapper 找到xml:
要么mapper和xml 具有相同的目录
要么在yml 文件中指定xml 位置
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: njw19920905
url: jdbc:mysql://47.96.95.15:3306/sell?characterEncoding=utf-8&useSSL=false
mybatis:
configuration:
map-underscore-to-camel-case: true
# 控制台日志配置
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
mapper-locations: classpath:mapper/*.xml
4.2.4验证
package com.example.mybaits.dao;
import com.example.mybaits.domain.Category;
import com.google.gson.Gson;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.junit.runner.RunWith;
@RunWith(SpringRunner.class)
@SpringBootTest
public class CategoryMapperTest {
@Autowired
private CategoryMapper categoryMapper;
@Test
public void queryByid() {
Gson gson = new Gson();
Category one = categoryMapper.queryByid(100001);
System.out.print(gson.toJson(one));
}
}
来源：CSDN
作者：Insist___
链接：https://blog.csdn.net/Insist___/article/details/104219471