Mybatis基础

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mb5fed701509fd9 2021-07-17 22:35:00

文章标签 sql 配置文件 xml apache 加载 文章分类 代码人生

Mybatis基础

1.结构图

2.配置文件

jdbc

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/db1
username=root
password=root

log4j(不是必须)

# Global logging configuration
# ERROR WARN INFO DEBUG
log4j.rootLogger=DEBUG, stdout
# 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

MyBatisConfig

<?xml version="1.0" encoding="UTF-8" ?>
<!--MyBatis的DTD约束-->
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!--configuration 核心根标签-->
<configuration>

    <!--引入数据库连接的配置文件-->
    <properties resource="jdbc.properties"/>

    <!--配置LOG4J-->
    <settings>
        <setting name="logImpl" value="log4j"/>
    </settings>

    <!--起别名-->
    <typeAliases>
        <typeAlias type="com.ding.bean.Student" alias="student"/>
        <!--<package name="com.ding.bean"/>-->
    </typeAliases>

    <!--environments配置数据库环境，环境可以有多个。default属性指定使用的是哪个-->
    <environments default="mysql">
        <!--environment配置数据库环境  id属性唯一标识-->
        <environment id="mysql">
            <!-- transactionManager事务管理。  type属性，采用JDBC默认的事务-->
            <transactionManager type="JDBC"></transactionManager>
            <!-- dataSource数据源信息   type属性 连接池-->
            <dataSource type="POOLED">
                <!-- property获取数据库连接的配置信息 -->
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${username}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
    </environments>

    <!-- mappers引入映射配置文件 -->
    <mappers>
        <!-- mapper 引入指定的映射配置文件   resource属性指定映射配置文件的名称 -->
        <mapper resource="StudentMapper.xml"/>
    </mappers>
</configuration>

StudentMapper

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

<!--
    mapper：核心根标签
    namespace属性：名称空间
-->
<mapper namespace="StudentMapper">
    <!--
        select：查询功能的标签
        id属性：唯一标识
        resultType属性：指定结果映射对象类型
        parameterType属性：指定参数映射对象类型
    -->
    <select id="selectAll" resultType="student">
        select * from student
    </select>

    <select id="selectById" resultType="student" parameterType="int">
        select * from student where id=#{id}
    </select>

    <insert id="insert" parameterType="student">
        insert into student values(#{id},#{name},#{age})
    </insert>

    <update id="update" parameterType="student">
        update student set name=#{name},age=#{age} where id=#{id}
    </update>

    <delete id="delete" parameterType="int">
        delete from student where id=#{id}
    </delete>
</mapper>

3.实体类

package com.ding.bean;

public class Student {
    private Integer id;
    private String name;
    private Integer age;

    public Student() {
    }

    public Student(Integer id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = 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 +
                '}';
    }
}

4.测试类

package com.ding.dao;

import com.ding.bean.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 org.junit.Test;

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

/**
 * @Description TODO
 * @Author 丁帅帅
 * @Date 21/07/17 14:57
 * @Version 1.0
 */
public class StudentTest01 {


    /**
     * 查询全部
    */
    @Test
    public void selectAll() throws Exception{
        //1.加载核心配置文件
        //InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        InputStream is = StudentTest01.class.getClassLoader().getResourceAsStream("MyBatisConfig.xml");

        //2.获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        //3.通过SqlSession工厂对象获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //4.执行映射配置文件中的sql语句，并接收结果
        List<Student> list = sqlSession.selectList("StudentMapper.selectAll");

        //5.处理结果
        for (Student stu : list) {
            System.out.println(stu);
        }

        //6.释放资源
        sqlSession.close();
        is.close();
    }

    /*
        根据id查询
     */
    @Test
    public void selectById() throws Exception{

        //1.加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        //2.获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        //3.通过工厂对象获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //4.执行映射配置文件中的sql语句,并接收结果
        Student stu = sqlSession.selectOne("StudentMapper.selectById", 3);

        //5.处理结果
        System.out.println(stu);

        //6.释放资源
        sqlSession.close();
        is.close();

    }

    /**
     * 新增功能
     */
    @Test
    public void insert() throws Exception{

        //1.加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        //2,获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        //3.通过工厂对象获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //4.执行映射配置文件中的sql语句,并接收结果
        Student student = new Student(4, "周琦", 27);
        int result = sqlSession.insert("StudentMapper.insert", student);

        //5.提交事务
        sqlSession.commit();

        //6.处理结果
        System.out.println(result);

        //7.释放资源
        sqlSession.close();
        is.close();

    }

    /*
    修改功能
     */
    @Test
    public void update() throws Exception{

        //1.加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        //2.获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        //3.通过工厂对象获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //4.执行映射配置文件中的sql语句,并接收结果
        Student student = new Student(4, "周七", 47);
        int result = sqlSession.update("StudentMapper.update", student);

        //5.处理结果
        System.out.println(result);

        //6.释放资源
        sqlSession.close();
        is.close();
    }
    /*
    删除功能
     */
    @Test
    public void delete() throws Exception{
        //1.加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        //2.获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        //3.通过工厂对象获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //4.执行映射配置文件中的sql语句,并接收结果
        int result = sqlSession.delete("StudentMapper.delete", 4);

        //5.处理结果
        System.out.println(result);

        //6.释放资源
        sqlSession.close();
        is.close();
    }
}

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