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mybatis入门

时间：2024-07-20 22:07:10浏览次数：17  
标签：入门 brand private sqlSession mybatis import tb String

mybatis入门

官网https://mybatis.org/mybatis-3/zh_CN/getting-started.html

1. 入门案例

image-20240605191353109

1.1 创建user表，添加数据

create database mybatis;
use mybatis;

alter database mybatis charset utf8mb4; 
# 注意：不设置可能会出现报错 “ Incorrect string value: ‘\xE7\x94\xB7‘ for 	column ‘xx‘ at row x”									
drop table if exists tb_user;

create table tb_user(
                        id int primary key auto_increment,
                        username varchar(20),
                        password varchar(20),
                        gender char(1),
                        addr varchar(30)
);

INSERT INTO tb_user VALUES (1, 'zhangsan', '123', '男', '北京');
INSERT INTO tb_user VALUES (2, '李四', '234', '女', '天津');
INSERT INTO tb_user VALUES (3, '王五', '11', '男', '西安');

select * from tb_user;

1.2 创建模块，导入坐标

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>mybatis-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.20</version>
        </dependency>
        <!-- 添加logback-classic依赖 -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>
        <!-- 添加logback-core依赖 -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.2.3</version>
        </dependency>

    </dependencies>

</project>

1.3 编写mybatis核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="userMapper.xml"/>
    </mappers>
</configuration>

1.4 编写sql映射文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="test">
    <select id="selectAll" resultType="com.itheima.pojo.User">
        select * from tb_user
    </select>
</mapper>

1.5 编码

package com.itheima.pojo;

public class User {
    private Integer id;
    private String username;
    private String password;
    private String gender;
    private String addr;
  // get set 方法
}

package com.itheima;

import com.itheima.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.InputStream;
import java.util.List;

public class MybatisDemo {
    public static void main(String[] args) throws Exception {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();

        List<User> users = sqlSession.selectList("test.selectAll");

        System.out.println(users);

        users.forEach(System.out::println);

        sqlSession.close();
    }
}

2. Mapper代理开发

image-20240605205817415

image-20240605205919048

2.1 步骤1

image-20240605210541559

注意：创建resources的目录，通过com/itheima/mapper创建多级目录

2.2 步骤2

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.itheima.mapper.UserMapper"> # namespace为接口的全限定类名
    <select id="selectAll" resultType="com.itheima.pojo.User">
        select * from tb_user
    </select>
</mapper>

2.3 步骤3

image-20240605211155312

image-20240605211425734

    <mappers>
   <!-- <mapper resource="com/itheima/mapper/userMapper.xml"/>-->
        <package name="com.itheima.mapper"/> 统一扫描多个mapper.xml配置文件
    </mappers

2.4 步骤4

//        List<User> users = sqlSession.selectList("test.selectAll");
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List<User> users = userMapper.selectAll();

3. 核心配置文件

3.1 typeAliases

image-20240605212842654

4. 案例

image-20240605213412242

image-20240605213439070

4.1 准备工作

4.1 数据表

-- 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);

SELECT * FROM tb_brand;

4.2 实体类

public class Brand {
    // id 主键
    private Integer id;
    // 品牌名称
    private String brandName;
    // 企业名称
    private String companyName;
    // 排序字段
    private Integer ordered;
    // 描述信息
    private String description;
    // 状态：0：禁用  1：启用
    private Integer status;
    
    // get set 方法
}

4.3 测试用例

image-20240605215054151

4.4 mybatisX插件

image-20240605215135873

4.2 查询所有数据

image-20240605220237745

import com.itheima.pojo.Brand;

import java.util.List;

public interface BrandMapper {
    List<Brand> selectAll();
}


<?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.itheima.mapper.BrandMapper">
    <resultMap id="brandResultMap" type="brand">
        <result column="brand_name" property="brandName" />
        <result column="company_name" property="companyName" />
    </resultMap>

    <select id="selectAll" resultMap="brandResultMap">
        select *
        from tb_brand;
    </select>
</mapper>

package com.itheima.pojo;

import lombok.Data;

@Data
public class Brand {
    // id 主键
    private Integer id;
    // 品牌名称
    private String brandName;
    // 企业名称
    private String companyName;
    // 排序字段
    private Integer ordered;
    // 描述信息
    private String description;
    // 状态：0：禁用  1：启用
    private Integer status;
}

package com.itheima.test;

import com.itheima.mapper.BrandMapper;
import com.itheima.pojo.Brand;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MybatisTest {

    @Test
    public void testSelectAll() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();

        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        List<Brand> brands = brandMapper.selectAll();

        brands.forEach(System.out::println);

        sqlSession.close();
    }
}

4.3 查询某条数据

public interface BrandMapper {
    Brand selectById(int id);
}

<?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.itheima.mapper.BrandMapper">
    <resultMap id="brandResultMap" type="brand">
        <result column="brand_name" property="brandName"/>
        <result column="company_name" property="companyName"/>
    </resultMap>
	
    # parameterType="int" 可以省略
    <select id="selectById" parameterType="int" resultMap="brandResultMap">
        select * from tb_brand where id = #{id};
    </select>
</mapper>

    @Test
    public void testSelectById() throws IOException {
        int id = 2;
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();

        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        Brand brand = brandMapper.selectById(id);
        System.out.println(brand);

        sqlSession.close();
    }

4.4 条件查询

注意：数据库连接建议设置成utf-8编码，否则查询中文时容易查不出结果

<property name="url" value="jdbc:mysql:///mybatis?characterEncoding=UTF-8&amp;useSSL=false"/>

public interface BrandMapper {
    List<Brand> selectByCondition(@Param("status") int status, @Param("companyName") String companyName);
}

<select id="selectByCondition" resultMap="brandResultMap">
        select * from tb_brand
        <where>
            <if test="status != null">
                and status = #{status}
            </if>
            <if test="companyName != null ">
                and company_name like #{companyName}
            </if>
            <if test="brandName != null and brandName != '' ">
                and brand_name like #{brandName}
            </if>
        </where>
</select>

   public void testSelectByCondition() throws IOException {
        int status = 1;
        String companyName = "华为";
        String brandName = "华为";
        companyName = "%" + companyName + "%";
        brandName = "%" + brandName + "%";

        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();

        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        List<Brand> brands = brandMapper.selectByCondition(status, companyName, brandName);
        brands.forEach(System.out::println);
        sqlSession.close();
    }

4.5 添加数据

public interface BrandMapper {
    void add(Brand brand);
}

<insert id="add">
    insert into tb_brand (brand_name, company_name, ordered, description, status)
    values (#{brandName},#{companyName},#{ordered},#{description},#{status});
</insert>

   @Test
    public void testAdd() throws IOException {
        int status = 1;
        String companyName = "波导手机";
        String brandName = "波导";
        String description = "手机中的战斗机";
        int ordered = 100;


        //封装对象
        Brand brand = new Brand();
        brand.setStatus(status);
        brand.setCompanyName(companyName);
        brand.setBrandName(brandName);
        brand.setDescription(description);
        brand.setOrdered(ordered);

        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession(true); //设置自动提交事务

        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
        brandMapper.add(brand);
        // sqlSession.commit(); // 注意提交事务
        sqlSession.close();
    }

获取主键

<insert id="add" useGeneratedKeys="true" keyProperty="id">
    insert into tb_brand (brand_name, company_name, ordered, description, status)
    values (#{brandName},#{companyName},#{ordered},#{description},#{status});
</insert>

 SqlSession sqlSession = sqlSessionFactory.openSession(true);

BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);
brandMapper.add(brand);
Integer id = brand.getId();
System.out.println(id);
//sqlSession.commit();
sqlSession.close();

标签：入门,brand,private,sqlSession,mybatis,import,tb,String
From： https://www.cnblogs.com/xinmomoyan/p/18313884

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