MyBatis简明教程-手把手教你配环境-maven+idea

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MyBatis中文官方文档

什么是 MyBatis？
MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 XML 或注解来配置和映射原生类型、接口和 Java 的 POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录。

1.项目结构，该项目为一个简单的web项目，使用maven构建，关于如何使用maven创建项目，请自行百度

2.Student为对应数据库的实体类

package entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student implements Serializable {
    /**
     *
     */
    private Integer id;

    /**
     *
     */
    private String name;

    /**
     *
     */
    private String sex;

    /**
     *
     */
    private String specialty;

    /**
     *
     */
    private String grade;

    public Student(String name, String sex, String specialty, String grade) {
        this.name = name;
        this.sex = sex;
        this.specialty = specialty;
        this.grade = grade;
    }
}

3.创建mybatis-config.xml配置文件

<?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>

    <settings>
        <!-- Globally enables or disables any caches configured in any mapper under this configuration -->
        <setting name="cacheEnabled" value="false"/>
        <!-- Sets the number of seconds the driver will wait for a response from the database -->
        <setting name="defaultStatementTimeout" value="5"/>
        <!-- Enables automatic mapping from classic database column names A_COLUMN to camel case classic Java property names aColumn -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <!-- Allows JDBC support for generated keys. A compatible driver is required.
        This setting forces generated keys to be used if set to true,
         as some drivers deny compatibility but still work -->
        <setting name="useGeneratedKeys" value="true"/>
    </settings>

    <!-- Continue editing here -->
    <!-- 数据库环境 -->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/stumanage?characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>


    <!-- 映射文件 -->
    <mappers>
        <mapper resource="StudentMapper.xml"/>
    </mappers>

</configuration>

4.创建sql语句接口以及对应的mapper.xml文件

package dao;

import entity.Student;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

@Mapper
public interface StudentMapper {
    int insert(@Param("student") Student student);

    int insertSelective(@Param("student") Student student);

    int insertList(@Param("students") List<Student> students);

    int updateByPrimaryKeySelective(@Param("student") Student student);

    void delete(Integer integer);

    Student getStudentById(Integer integer);

    void update(Student student);

    Student selectAll();
}

<?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="dao.StudentMapper">
    <!--auto generated Code-->
    <resultMap id="BaseResultMap" type="entity.Student">
        <result column="id" property="id" jdbcType="INTEGER"/>
        <result column="name" property="name" jdbcType="VARCHAR"/>
        <result column="sex" property="sex" jdbcType="VARCHAR"/>
        <result column="specialty" property="specialty" jdbcType="VARCHAR"/>
        <result column="grade" property="grade" jdbcType="VARCHAR"/>
    </resultMap>

    <!--auto generated Code-->
    <sql id="Base_Column_List">
            id,
            `name`,
            sex,
            specialty,
            grade
    </sql>

    <!--auto generated Code-->
    <insert id="insert" parameterType="entity.Student">
        INSERT INTO student (
            name,
            sex,
            specialty,
            grade
        ) VALUES (
            #{name},
            #{sex},
            #{specialty},
            #{grade}
        )
    </insert>

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

    <update id="update" parameterType="entity.Student">
        update student
        set name = #{name}, sex = #{sex}, specialty = #{specialty}, grade = #{grade}
        where id = #{id}
    </update>

    <select id="getStudentById" parameterType="int" resultType="entity.Student">
        select *
        from student
        where id = #{id}
    </select>
    <!--若查询的返回结果是集合 则resultType类型应为具体类型 而不是list-->
    <select id="selectAll" resultType="entity.Student">
        select *
        from student
    </select>

    <!--auto generated Code-->
    <insert id="insertSelective" useGeneratedKeys="true" keyProperty="student.id">
        INSERT INTO student
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="student.id!=null">id,</if>
            <if test="student.name!=null">`name`,</if>
            <if test="student.sex!=null">sex,</if>
            <if test="student.specialty!=null">specialty,</if>
            <if test="student.grade!=null">grade,</if>
        </trim>
        VALUES
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="student.id!=null">#{student.id,jdbcType=INTEGER},
            </if>
            <if test="student.name!=null">#{student.name,jdbcType=VARCHAR},
            </if>
            <if test="student.sex!=null">#{student.sex,jdbcType=VARCHAR},
            </if>
            <if test="student.specialty!=null">#{student.specialty,jdbcType=VARCHAR},
            </if>
            <if test="student.grade!=null">#{student.grade,jdbcType=VARCHAR},
            </if>
        </trim>
    </insert>

    <!--auto generated Code-->
    <insert id="insertList">
        INSERT INTO student (
        id,
        `name`,
        sex,
        specialty,
        grade
        )VALUES
        <foreach collection="students" item="student" index="index" separator=",">
            (
            #{student.id,jdbcType=INTEGER},
            #{student.name,jdbcType=VARCHAR},
            #{student.sex,jdbcType=VARCHAR},
            #{student.specialty,jdbcType=VARCHAR},
            #{student.grade,jdbcType=VARCHAR}
            )
        </foreach>
    </insert>

    <!--auto generated Code-->
    <update id="updateByPrimaryKeySelective">
        UPDATE student
        <set>
            <if test="student.name != null">`name`= #{student.name,jdbcType=VARCHAR},</if>
            <if test="student.sex != null">sex= #{student.sex,jdbcType=VARCHAR},</if>
            <if test="student.specialty != null">specialty= #{student.specialty,jdbcType=VARCHAR},</if>
            <if test="student.grade != null">grade= #{student.grade,jdbcType=VARCHAR}</if>
        </set>
        WHERE id = #{student.id,jdbcType=INTEGER}
    </update>
</mapper>

5.测试类-增删查改

import entity.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.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

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

/**
 * @ClassName: Main
 * @Author: Leo
 * @Description:
 * @Date: 2019/4/8 21:13
 */
public class Main {
    private static Logger logger = LogManager.getLogger("Leo");

    public static void main(String[] args) {
        SqlSessionFactory sqlSessionFactory;
        SqlSession sqlSession;
        //配置文件路径
        String resources = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            //加载配置文件
            inputStream = Resources.getResourceAsStream(resources);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            sqlSession = sqlSessionFactory.openSession();
            //插入一条记录
            Student student = new Student("小明", "男", "数学", "大一");
            int insert = sqlSession.insert("insert", student);
            logger.debug("插入一条记录: " + insert);
            //根据学号查询记录
            Student student1 = sqlSession.selectOne("getStudentById", 1);
            logger.debug("根据学号查询: " + student1.toString());
            //查询所有记录
            List<Student> list = sqlSession.selectList("selectAll");
            for (Student student2 : list) {
                logger.debug("查询所有记录: " + student2.toString());
            }
            //更新一条记录
            Student student3 = new Student(1, "更新名字", "无", "人工智能", "大五");
            sqlSession.update("update", student3);
            //删除一条记录
            int delete = sqlSession.delete("delete", 2);
            logger.debug("删除一条记录: " + delete);
            sqlSession.commit();
            sqlSession.close();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }
}