MyBatis入门使用

1 环境

• jdk
• idea/eclipse
• mysql
• maven

2 步骤

2.1 在数据库创建表

create table stu
(
    stu_id int not null primary key,
    stu_name varchar(10) null
);

pom文件导入mybatis,mysql依赖

    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.6</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.17</version>
    </dependency>

2.2 创建实体类

2.2.1 在src/main/java下创建domain包

2.2.2 在domain包下创建Student类

package com.yhb.domain;
/** 
* @author YangHaiBo 
* @create 2019-09-20 18:43
*/
public class Student {
    private Integer studentId;
    private String studentName;
    //已省略get/set方法
}

2.3 创建映射类

2.3.1 创建dao包

2.3.2 创建StudentMapper接口

package com.yhb.dao;
import com.yhb.domain.Student;
import java.util.List;
public interface StudentMapper {
    List<Student> searchAll();   
    Student searchById(Integer id);
}

2.4 创建映射文件

2.4.1 在src/main/resources/创建mapper文件夹

2.4.2 创建StudentMapper.xml文件

<?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.yhb.dao.StudentMapper">   
    <resultMap type="com.yhb.domain.Student" id="BaseMap"> 
        <!-- 以此把实体类的字段和sql的语句中的字段对应 -->
        <id javaType="Integer" column="stu_id" property="studentId"/> 
        <result javaType="String" column="stu_name" property="studentName"/>                </resultMap>
    <select id="searchById" resultType="com.yhb.domain.Student" parameterType="Integer">        select * from stu where stu_id = #{id}   
    </select>  
    <select id="searchAll" resultMap="BaseMap">  
        select * from stu    </select>
</mapper>

2.5 创建mybatis配置文件

2.5.1 在src/resources/下创建mybatis-config.xml文件

<?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">
<!-- 配置读取database.properties里面连接数据库信息 -->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="jdbc"/>
            <dataSource type="pooled">
                <property name="url" value="jdbc:mysql://localhost:3306/testdata?useUnicode=true&amp;characterEncoding=utf-8&amp;useSSL=true&amp;serverTimezone=UTC"/>
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>
    <!--  建立与stumapper.xml映射文件的对应关系 -->
    <mappers>
        <mapper resource="mapper/StudentMapper.xml"/>
    </mappers>
</configuration>

2.6 编写测试类

2.6.1 创建测试类

在src/main/test/下创建mybatis包

2.6.2 编写测试类

package mybatis;
public class TestMybatis {
    @Test
    public void testSearch() throws IOException {
        //1.先定义一个变量,先保存mybatis-config.xml文件  
        String resource = "mybatis-config.xml";    
        //2.产生api对象，产生会话工厂  
        SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream(resource));
        //3.通过会话工厂得到会话 
        SqlSession session = sf.openSession(); 
        //4.通过session得到需要的数据   
        StudentMapper studentMapper = session.getMapper(StudentMapper.class);        List<Student> stuList = studentMapper.searchAll();  
        //5.遍历   
        System.out.println(stuList == null ? "stuList is null" : "stuList is not null");        for (Student stu : stuList) {  
            System.out.println(stu != null ? stu.toString() : "stu null");  
        }  
    }
}

2.7 结果

显示出查询出的数据库内结果

原文地址：https://www.cnblogs.com/guming1125/p/11560226.html