MyBatis学习日志

导入依赖的jar包

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.10</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

创建一个po类

package com.yogurt.po;

import lombok.*;

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString
public class Student {

    private Integer id;

    private String name;

    private Integer score;

    private Integer age;

    private Integer gender;

}

编写mapper映射文件(编写SQL)

<!-- StudentMapper.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="test">
    <select id="findAll" resultType="com.yogurt.po.Student">
        SELECT * FROM student;
    </select>

    <insert id="insert" parameterType="com.yogurt.po.Student">
        INSERT INTO student (name,score,age,gender) VALUES (#{name},#{score},#{age},#{gender});
    </insert>
    
    <delete id="delete" parameterType="int">
        DELETE FROM student WHERE id = #{id};
    </delete>
</mapper>

编写数据源properties文件

db.url=jdbc:mysql://192.168.183.129:3306/yogurt?characterEncoding=utf8
db.user=root
db.password=root
db.driver=com.mysql.jdbc.Driver

编写全局配置文件(主要是配置数据源信息)

<?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>
    <!-- 配置文件信息 -->
    <properties resource="properties/db.properties"></properties>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <!-- 从配置文件中加载属性 -->
                <property name="driver" value="${db.driver}"/>
                <property name="url" value="${db.url}"/>
                <property name="username" value="${db.user}"/>
                <property name="password" value="${db.password}"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!-- 加载前面编写的SQL语句的文件 -->
        <mapper resource="StudentMapper.xml"/>
    </mappers>

</configuration>

编写dao类

package com.yogurt.dao;

import com.yogurt.po.Student;
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.IOException;
import java.io.InputStream;
import java.util.List;

public class StudentDao {

    private SqlSessionFactory sqlSessionFactory;

    public StudentDao(String configPath) throws IOException {
        InputStream inputStream = Resources.getResourceAsStream(configPath);
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }

    public List<Student> findAll() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<Student> studentList = sqlSession.selectList("findAll");
        sqlSession.close();
        return studentList;
    }

    public int addStudent(Student student) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int rowsAffected = sqlSession.insert("insert", student);
        sqlSession.commit();
        sqlSession.close();
        return rowsAffected;
    }

    public int deleteStudent(int id) {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int rowsAffected = sqlSession.delete("delete",id);
        sqlSession.commit();
        sqlSession.close();
        return rowsAffected;
    }
}

测试

public class SimpleTest {

    private StudentDao studentDao;

    @Before
    public void init() throws IOException {
        studentDao = new StudentDao("mybatis-config.xml");
    }

    @Test
    public void insertTest() {
        Student student = new Student();
        student.setName("yogurt");
        student.setAge(24);
        student.setGender(1);
        student.setScore(100);
        studentDao.addStudent(student);
    }

    @Test
    public void findAllTest() {
        List<Student> all = studentDao.findAll();
        all.forEach(System.out::println);
    }
}

 

 

总结：

1. 编写mapper.xml，书写SQL，并定义好SQL的输入参数，和输出参数
2. 编写全局配置文件，配置数据源，以及要加载的mapper.xml文件
3. 通过全局配置文件，创建SqlSessionFactory
4. 每次进行CRUD时，通过SqlSessionFactory创建一个SqlSession
5. 调用SqlSession上的selectOne，selectList，insert，delete，update等方法，传入mapper.xml中SQL标签的id，以及输入参数