MyBatis学习（二）MyBatis-Statement方式的增删改查

1、前期准备

项目骨架图如下所示

1、配置conf.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>

    <!--  通过 environments 的 default值 和 environment 的 id 来指定mybatis运行时的数据库环境  -->

    <environments default="development">

        <!--    开发环境(本机)、environment可以有多套    -->

        <environment id="development">

            <!--  事务提交方式

                  JDBC：利用JDBC处理事务（commit rollback close）

                  MANAGED：将事务交给其他组件托管（Spring、jobss），默认情况下会关闭连接。

              -->

            <transactionManager type="JDBC"/>

            <!--   数据源类型

                   POOLED：使用数据库连接池

                   UNPOOLED：传统的JDBC模式(消耗性能、不推荐)

                   JNDI：从tomcat中获取内置数据库连接池

                     -->

            <dataSource type="POOLED">

                <!-- 配置数据库信息 -->

                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>

                <property name="url" value="jdbc:mysql://localhost:3306/xiao?serverTimezone=GMT%2B8"/>

                <property name="username" value="root"/>

                <property name="password" value="123456"/>

            </dataSource>

        </environment>

    </environments>

    <mappers>

        <!--   加载映射文件     -->

        <mapper resource="com/feng/entity/studentMapper.xml"/>

    </mappers>

</configuration>

2、配置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：该mapper.xml映射文件的唯一标识-->

<mapper namespace="com.feng.entity.studentMapper">

    <!--  通过 namespace.id来定位该sql  -->

    <!--  各种标签的id；

    parameterType:输入参数的类型；

    resultType:查询的返回结果的类型(具体对象映射到路径)

    -->

    <select id="queryStudentByStuNo" parameterType="int" resultType="com.feng.entity.Student">

        select * from student where stuno = #{stuNo}

    </select>

    <select id="queryAllStudents" resultType="com.feng.entity.Student">

        select * from student

    </select>

    <insert id="addStudent" parameterType="com.feng.entity.Student">

        insert into student(stuno,stuname,stuage,graname) values(#{stuNo},#{stuName},#{stuAge},#{graName})

    </insert>

    <update id="updateStudentByStuNo" parameterType="com.feng.entity.Student">

        update student set stuname=#{stuName},stuage=#{stuAge},graname=#{graName} where stuno=#{stuNo}

    </update>

    <delete id="deleteStudentByStuNo" parameterType="int">

        delete from student where stuno = #{stuNo}

    </delete>

</mapper>

3、写好学生类和创建对应的表

package com.feng.entity;

public class Student {

    private int stuNo;

    private String stuName;

    private int stuAge;

    private String graName;

    public int getStuNo() {

        return stuNo;

    }

    public void setStuNo(int stuNo) {

        this.stuNo = stuNo;

    }

    public String getStuName() {

        return stuName;

    }

    public void setStuName(String stuName) {

        this.stuName = stuName;

    }

    public int getStuAge() {

        return stuAge;

    }

    public void setStuAge(int stuAge) {

        this.stuAge = stuAge;

    }

    public String getGraName() {

        return graName;

    }

    public void setGraName(String graName) {

        this.graName = graName;

    }

    public Student(int stuNo, String stuName, int stuAge, String graName) {

        this.stuNo = stuNo;

        this.stuName = stuName;

        this.stuAge = stuAge;

        this.graName = graName;

    }

    public Student() {

    }

    @Override

    public String toString() {

        return '{'+"stuNo=" + stuNo +

                ", stuName='" + stuName + '\'' +

                ", stuAge=" + stuAge +

                ", graName='" + graName + '\'' +

                '}';

    }

}

2、编写测试类进行测试

package com.feng.entity;

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.Reader;

import java.util.List;

public class Test {

    // 1、查询单个学生

    public static void queryStudentByStuNo() throws IOException {

        // conf.xml ---->  reader

        Reader reader = Resources.getResourceAsReader("com/feng/conf.xml");

        // reader ---> SqlSession

        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

        SqlSession session = sessionFactory.openSession();

        // arg1: namespace + id 确定 sql 、 arg2: 输入参数

        String statement = "com.feng.entity.studentMapper.queryStudentByStuNo";

        Student student = session.selectOne(statement, 1);

        System.out.println(student);

        session.close();

    }

    // 2、查询全部学生

    public static void queryAllStudents() throws IOException {

        Reader reader = Resources.getResourceAsReader("com/feng/conf.xml");

        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

        SqlSession session = sessionFactory.openSession();

        // arg1: namespace + id 确定 sql 、 arg2: 输入参数

        String statement = "com.feng.entity.studentMapper.queryAllStudents";

        List<Student> students = session.selectList(statement);

        System.out.println(students);

        session.close();

    }

    // 3、增加学生

    public static void addStudent() throws IOException {

        Reader reader = Resources.getResourceAsReader("com/feng/conf.xml");

        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

        SqlSession session = sessionFactory.openSession();

        String statement = "com.feng.entity.studentMapper.addStudent";

        Student student = new Student(3, "柴犬", 25, "六年级");

        // statement：指定执行的sql、student：sql中需要的参数

        int count = session.insert(statement, student);

        session.commit();   // 提交事务

        System.out.println("增加了"+count+"个学生");

        session.close();

    }

    // 4、删除学生

    public static void updateStudentByStuNo() throws IOException {

        Reader reader = Resources.getResourceAsReader("com/feng/conf.xml");

        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

        SqlSession session = sessionFactory.openSession();

        String statement = "com.feng.entity.studentMapper.updateStudentByStuNo";

        Student student = new Student();

        // 修改那个人, where stuNo = 2

        student.setStuNo(2);

        // 修改成啥样子

        student.setStuName("三哈");

        student.setStuAge(25);

        student.setGraName("六年级");

        int count = session.update(statement, student);

        session.commit();   // 提交事务

        System.out.println("修改"+count+"个学生");

        session.close();

    }

    // 4、增加学生

    public static void deleteStudentByStuNo() throws IOException {

        Reader reader = Resources.getResourceAsReader("com/feng/conf.xml");

        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

        SqlSession session = sessionFactory.openSession();

        String statement = "com.feng.entity.studentMapper.deleteStudentByStuNo";

        int count = session.delete(statement, 3);

        session.commit();   // 提交事务

        System.out.println("删除了"+count+"个学生");

        session.close();

    }

    public static void main(String[] args) throws IOException {

        queryAllStudents();

        addStudent();

//        deleteStudentByStuNo();

        updateStudentByStuNo();

        queryAllStudents();

    }

}

巴特西

MyBatis学习（二）MyBatis-Statement方式的增删改查

1、前期准备

1、配置conf.xml

2、配置studentMapper.xml

3、写好学生类和创建对应的表

2、编写测试类进行测试

3、运行结果

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