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();
    }
}

3、运行结果