Mybatis---Mybatis入门

一、配置环境

下载地址：https://github.com/mybatis/mybatis-3/releases

使用MyBatis框架非常简单，只需在应用程序中引入MyBatis的核心包和lib目录中的依赖包即可。

二、创建项目

需要用到的包有Mybatis、jdbc驱动包、Junit5(eclipse自带)

注意：StudentMapper.xml是创建在Pojo包里，而mybatis-cofigure.xml是创建在src下

三、贴代码

log4j.properties

# Global logging configuration
log4j.rootLogger=ERROR, stdout
# MyBatis logging configuration...
log4j.logger.com.ssm=DEBUG
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

Student.java

package Pojo;

public class Student {
	private Integer id;
	private String name;
	private Integer age;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
	}
	
}

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">
<!-- namespace表示命名空间 -->
<mapper namespace="Pojo.StudentMapper">
    <!--根据客户编号获取客户信息 -->
    <select id="findStudentById" parameterType="Integer" 
            resultType="Pojo.Student">
        select * from t_student where id = #{id}
   </select>

</mapper>

MybatisTest.java

package test;

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;
import org.junit.Test;
import Pojo.Student;
/**
 * 入门程序测试类
 */
public class MybatisTest {
    /**
     * 根据客户编号查询客户信息
     */
    @Test
    public void findStudentByIdTest() throws Exception {
        // 1、读取配置文件
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        // 2、根据配置文件构建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory =new SqlSessionFactoryBuilder().build(inputStream);
        // 3、通过SqlSessionFactory创建SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 4、SqlSession执行映射文件中定义的SQL，并返回映射结果,这个是查询单个id
        Student student = sqlSession.selectOne("Pojo" + ".StudentMapper.findStudentById", 1); 
        // 打印输出结果
        System.err.println("查询结果如下：");
        System.out.println(student.toString());
        // 5、关闭SqlSession
        sqlSession.close();
    }
}
 

在navicat创建一个叫mybatis的数据库，新建表t_student.

写进几条记录

mybatis-configure.xml

<?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>
    <!--1.配置环境 ，默认的环境id为mysql-->
    <environments default="mysql">
        <!--1.2.配置id为mysql的数据库环境 -->
        <environment id="mysql">
            <!-- 使用JDBC的事务管理 -->
            <transactionManager type="JDBC" />
            <!--数据库连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url"  value="jdbc:mysql://127.0.0.1/mybaits" />
                <property name="username" value="root" />
                <property name="password" value="1234" />
            </dataSource>
        </environment>
    </environments>
    <!--2.配置Mapper的位置 -->
    <mappers>
        <mapper resource="Pojo/StudentMapper.xml" />
    </mappers>
</configuration>

在MybatisTest.java 右键 run as -----Junit test

运行截图: