Mybatis学习笔记（一）--- 开始使用Mybatis

最新推荐文章于 2025-09-12 18:08:49 发布

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原文链接：https://my.oschina.net/u/1044988/blog/707124

文章标签：

#java #python #数据库

本文介绍了一个使用MyBatis实现的学生信息管理系统案例。该系统通过Java和MyBatis框架完成学生数据的增删改查操作，并提供了单元测试验证功能。

2019独角兽企业重金招聘Python工程师标准>>>

相比较传统的JDBC，使用Mybatis的好处在于省略了获取和释放数据库连接，准备PreparedStatement，向SQL中插入参数等代

码，使开发人员更加关注于数据持久代码的开发。本篇博客就从通过一个Demo来讲解如何使用Mybatis这个简单易用的持久层解决方案。

创建STUDENTS数据表并向其中插入一些样本数据

CREATE TABLE STUDENTS
(
stud_id int(11) NOT NULL AUTO_INCREMENT,
name varchar(50) NOT NULL,
email varchar(50) NOT NULL,
dob date DEFAULT NULL,
PRIMARY KEY (stud_id)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

/*Sample Data for the students table */
insert into students(stud_id,name,email,dob)
values (1,'Student1', 'student1@gmail.com','1983-06-25');

insert into students(stud_id,name,email,dob)
values (2,'Student2', 'student2@gmail.com','1983-06-25');

使用MAVEN创建JAVA项目

项目结构如图所示：

pom.xml文件为：

<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>com.learn</groupId>
	<artifactId>mybatis</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>mybatis</name>
	<url>http://maven.apache.org</url>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.mybatis</groupId>
			<artifactId>mybatis</artifactId>
			<version>3.2.2</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.22</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>1.7.5</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
			<version>1.7.5</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.17</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.11</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
</project>

创建mybatis-config.xml和StudentMapper.xml配置文件

mybatis-config.xml文件为：

<?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>
	<typeAliases>
		<typeAlias alias="Student" type="com.learn.mybatis_demo.domain.Student" />
	</typeAliases>
	<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://localhost:3306/mybatis" />
				<property name="username" value="root" />
				<property name="password" value="sa12345" />
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="com/learn/mybatis_demo/mappers/StudentMapper.xml" />
	</mappers>
</configuration>

StudentMapper.xml文件为：

<?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.learn.mybatis_demo.mappers.StudentMapper">
	<resultMap type="Student" id="StudentResult">
		<id property="studId" column="stud_id" />
		<result property="name" column="name" />
		<result property="email" column="email" />
		<result property="dob" column="dob" />
	</resultMap>

	<select id="findAllStudents" resultMap="StudentResult">
		SELECT * FROM STUDENTS
	</select>
	
	<select id="findStudentById" parameterType="int" resultType="Student">
		SELECT STUD_ID AS STUDID, NAME, EMAIL, DOB
		FROM STUDENTS WHERE STUD_ID=#{studId}
	</select>
	
	<insert id="insertStudent" parameterType="Student">
		INSERT INTO STUDENTS(STUD_ID,NAME,EMAIL,DOB)
		VALUES(#{studId},#{name},#{email},#{dob})
	</insert>
</mapper>

创建MyBatisSqlSessionFactory单例

package com.learn.mybatis_demo.util;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisSqlSessionFactory {

	private static SqlSessionFactory sqlSessionFactory;

	public static SqlSessionFactory getSqlSessionFactory() {
		if(sqlSessionFactory == null) {
			InputStream inputStream;
			try {
				inputStream = Resources.getResourceAsStream("mybatis-config.xml");
				sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
			} catch (IOException e) {
				throw new RuntimeException(e.getCause());
			}
		}
		return sqlSessionFactory;
	}
	
	public static SqlSession openSession() {
		return getSqlSessionFactory().openSession();
	}
}

创建StudentMapper接口和StudentService

package com.learn.mybatis_demo.domain;

import java.util.Date;

public class Student {

	private Integer studId;
	private String name;
	private String email;
	private Date dob;

	public Integer getStudId() {
		return studId;
	}

	public void setStudId(Integer studId) {
		this.studId = studId;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public Date getDob() {
		return dob;
	}

	public void setDob(Date dob) {
		this.dob = dob;
	}
}

package com.learn.mybatis_demo.mappers;

import java.util.List;

import com.learn.mybatis_demo.domain.Student;

public interface StudentMapper {

	List<Student> findAllStudents();
	Student findStudentById(Integer id);
	void insertStudent(Student student);
}

package com.learn.mybatis_demo.service;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.learn.mybatis_demo.domain.Student;
import com.learn.mybatis_demo.mappers.StudentMapper;
import com.learn.mybatis_demo.util.MyBatisSqlSessionFactory;

public class StudentService {

	private Logger logger = LoggerFactory.getLogger(getClass());
	
	public List<Student> findAllStudents() {
		SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
		try {
			StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
			return studentMapper.findAllStudents();
		} finally {
			sqlSession.close();
		}
	}
	
	Student findStudentById(Integer studId) {
		logger.debug("Select Student By ID :{}", studId);
		SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
		try {
			StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
			return studentMapper.findStudentById(studId);
		} finally {
			sqlSession.close();
		}
	}
	void createStudent(Student student) {
		SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
		try {
			StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
			studentMapper.insertStudent(student);
			sqlSession.commit();
		} finally {
			sqlSession.close();
		}
	}
}

创建JUnit测试来测试StudentService

package com.learn.mybatis_demo.service;

import java.util.Date;
import java.util.List;

import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;

import com.learn.mybatis_demo.domain.Student;

public class StudentServiceTest {

	private static StudentService studentService;
	
	@BeforeClass
	public static void setUp() {
		studentService = new StudentService(); 
	}
	
	@AfterClass
	public static void teardown() {
		studentService = null;
	}
	
	@Test
	public void testFindAllStudents() {
		List<Student> students = studentService.findAllStudents();
		Assert.assertNotNull(students);
		for (Student student : students) {
			System.out.println(student);
		}
	}
	
	@Test
	public void testFindStudentById() {
		Student student = studentService.findStudentById(1);
		Assert.assertNotNull(student);
		System.out.println(student);
	}
	
	@Test
	public void testCreateStudent() {
		Student student = new Student();
		int id = 3;
		student.setStudId(id);
		student.setName("student_" + id);
		student.setEmail("student_" + id + "@gmail.com");
		student.setDob(new Date());
		studentService.createStudent(student);
		Student newStudent = studentService.findStudentById(id);
		Assert.assertNotNull(newStudent);
	}
}