MyBatis 第一个项目

本文主要是介绍MyBatis 第一个项目，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

code：https://github.com/Maoxim/MyBatis-First-Program

1.导入依赖

    <!--导入依赖-->
    <dependencies>
        <!--mysqlq驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.26</version>
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.4</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

2.创建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>
    <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/mybatis?userSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="com/maoxin/dao/UserMapper.xml" />
    </mappers>
</configuration>

3.创建MybatisUtils工具类

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package com.maoxin.utils;

import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MybatisUtils {
    static SqlSessionFactory sqlSessionFactory = null;

    public MybatisUtils() {
    }

    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();
    }

    static {
        try {
            String resource = "config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = (new SqlSessionFactoryBuilder()).build(inputStream);
        } catch (IOException var2) {
            var2.printStackTrace();
        }

    }
}

4.创建pojo实体类

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package com.maoxin.pojo;

public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return this.id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return this.pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
}

5.创建接口

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package com.maoxin.dao;

import com.maoxin.pojo.User;
import java.util.List;

public interface UserDao {
    List<User> getUserList();
}

6.创建接口实现类（Mapper配置文件）

<?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.maoxin.dao.UserDao">
    <select id="getUserList" resultType="com.maoxin.pojo.User">
        select * from USER
    </select>
</mapper>

7.创建测试文件

package com.maoxin.dao;

import com.maoxin.pojo.User;
import com.maoxin.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){

        //1.获取SqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //2.执行SQL
        // 方式一：getMapper
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> userList = userDao.getUserList();
        for (User user : userList) {
            System.out.println(user.getPwd());
        }

        //关闭sqlSession
        sqlSession.close();
    }
}

需要注意的点：

1.需要在核心配置文件(config.xml)中注册mappers

    <mappers>
        <mapper resource="com/maoxin/dao/UserMapper.xml" />
    </mappers>

2.需要注意资源文件打包问题

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>

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