IDEA使用MyBatis【超级详细，绝对能运行】

先上成功运行结果：

1.新建项目 ，这里新建一个普通的JavaSE项目，当然你也可以新建web项目

 然后点Next，然后再点Finish就好了。

2.创建resources文件夹，该文件夹和java文件夹同一级

创建完以后，在文件夹上点右键：

3.在Java文件夹中新建学生实体类，对应数据库中的学生表：

package com.leo;

import lombok.Data;

@Data
public class Student {
    /**
     *
     */
    private Integer id;

    /**
     *
     */
    private String name;

    /**
     *
     */
    private String sex;

    /**
     *
     */
    private String specialty;

    /**
     *
     */
    private String grade;
}

然后在类名上按Alt+Insert，会出来这个，没有的话应该是没装插件，先去装mybatis的插件：

然后在studentmapper.xml 中写sql语句：

<?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="com.leo.StudentMapper">
    <!--auto generated Code-->
    <resultMap id="BaseResultMap" type="com.leo.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" useGeneratedKeys="true" keyProperty="student.id">
        INSERT INTO student (
            id,
            `name`,
            sex,
            specialty,
            grade
        ) VALUES (
            #{student.id,jdbcType=INTEGER},
            #{student.name,jdbcType=VARCHAR},
            #{student.sex,jdbcType=VARCHAR},
            #{student.specialty,jdbcType=VARCHAR},
            #{student.grade,jdbcType=VARCHAR}
        )
    </insert>

    <!--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>


    <select id="selectOne" resultType="com.leo.Student">
        select * from student where id = #{id};
    </select>


</mapper>

然后新建xml文件，命名为config.xml,这是mybatis的配置文件：

<?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>

最后写一个含有主函数的类测试一下：

public static void main(String[] args) {
        // 根据 config.xml 配置的信息得到 sqlSessionFactory
        String resource = "config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 然后根据 sqlSessionFactory 得到 session
        SqlSession session = sqlSessionFactory.openSession();
        // 最后通过 session 的 selectList() 方法调用 sql 语句 listStudent
        Student student = session.selectOne("selectOne", 6);
        System.out.println(student.toString());
    }