利用MyBatis实现查询所有数据

这操作真心记不住。。。。。还是写一遍加深记忆

1.首先创建user表，添加数据.

create datebase fuck;

use fuck;

// 删除tb_brand表
drop table if exists tb_brand;
// 创建tb_brand表
create table tb_brand
(
    -- id 主键
    id           int primary key auto_increment,
    -- 品牌名称
    brand_name   varchar(20),
    -- 企业名称
    company_name varchar(20),
    -- 排序字段
    ordered      int,
    -- 描述信息
    description  varchar(100),
    -- 状态：0：禁用  1：启用
    status       int
);
// 添加数据
insert into tb_brand (brand_name, company_name, ordered, description, status)
values ('三只松鼠', '三只松鼠股份有限公司', 5, '好吃不上火', 0),
       ('华为', '华为技术有限公司', 100, '华为致力于把数字世界带入每个人、每个家庭、每个组织，构建万物互联的智能世界', 1),
       ('小米', '小米科技有限公司', 50, 'are you ok', 1);

2.创建Maven模块，导入坐标

导入坐标

 
            
        
            mysql
            mysql-connector-java
            8.0.28
        
             
        
            org.mybatis
            mybatis
            3.5.5
        
            
        
            junit
            junit
            4.12
            test
        

            
        
            org.slf4j
            slf4j-api
            1.7.20
        
            
        
            ch.qos.logback
            logback-classic
            1.2.3
        
            
        
            ch.qos.logback
            logback-core
            1.2.3
        

    

 3.编写MyBatis的核心配置文件，并且导入logback.xml文件

（1）mybatis配置文件

并且把相应的数据库信息导入进去

（2） logback.xml文件

    
    
        
            [%level] %blue(%d{HH:mm:ss.SSS}) %cyan([%thread]) %boldGreen(%logger{15}) - %msg %n
        
    

    
        
    


    
    
        
    

4.编写pojo实体类,用get 、set方法

package com.fuck.pojo;

public class Brand {
       private Integer id;
        private String brandName;
        private String companyName;
        private Integer ordered;
        private String description;
        private Integer status;

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }

        public String getBrandName() {
            return brandName;
        }

        public void setBrandName(String brandName) {
            this.brandName = brandName;
        }

        public String getCompanyName() {
            return companyName;
        }

        public void setCompanyName(String companyName) {
            this.companyName = companyName;
        }

        public Integer getOrdered() {
            return ordered;
        }

        public void setOrdered(Integer ordered) {
            this.ordered = ordered;
        }

        public String getDescription() {
            return description;
        }

        public void setDescription(String description) {
            this.description = description;
        }

        public Integer getStatus() {
            return status;
        }

        public void setStatus(Integer status) {
            this.status = status;
        }

        @Override
        public String toString() {
            return "Brand{" +
                    "id=" + id +
                    ", brandName='" + brandName + '\'' +
                    ", companyName='" + companyName + '\'' +
                    ", ordered=" + ordered +
                    ", description='" + description + '\'' +
                    ", status=" + status +
                    '}';
        }
}

5.创建mapper接口

package com.fuck.mapper;
import com.fuck.pojo.Brand;
import java.util.List;
public interface BrandMapper {
    //查询所有
    public List selectAll();
}

6.创建SqlSessionFactory工具类

package com.fuck.Utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
public class SqLSessionFactoryUtils {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }
    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
}

总的项目结构

7.创建Mapper映射文件，并写入sql查询语句

BrandMapper.xml文件

    

        
        
    
   
    
select * from tb_brand;
    

8. 最后编写测试类

MyBatisTest

package com.fuck.test;

import com.fuck.Utils.SqLSessionFactoryUtils;
import com.fuck.mapper.BrandMapper;
import com.fuck.pojo.Brand;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.junit.Test;

import java.util.Base64;
import java.util.List;

public class MyBatisTest {
//      调用SqlSessionFactory方法 构建出SqlSessionFactory的实例 factory
SqlSessionFactory factory= SqLSessionFactoryUtils.getSqlSessionFactory();
//   利用注解
    @Test
    public void testSelectAll(){
//        获取SqlSession
        SqlSession sqlSession= factory.openSession();
//        获取BrandMapper
        BrandMapper brandmapper=sqlSession.getMapper(BrandMapper.class);
//        调用方法
        List brands=brandmapper.selectAll();
//         输出
        System.out.println(brands);
//         关闭sqlSession
        sqlSession.close();
        
    }
}

 运行结果