Mybatis(二） 第一个Mybatis程序

2. 第一个Mybatis程序

       思路：搭建环境—>导入Mybatis程序à编写代码à测试

2.1 搭建环境

       1.搭建数据库

       CREATE DATABASE `mybatis`;

USE `mybatis`;

 

CREATE TABLE `user`(

              `id` INT(20) NOT NULL PRIMARY KEY,

              `name` VARCHAR(30) DEFAULT NULL,

              `pwd` VARCHAR(30) DEFAULT NULL 

);ENGINE=INNODB DEFAULT CHARSET=utf8;

 

INSERT INTO `user` (`id`,`name`,`pwd`) VALUES (1,'十三','123456'),

(2,'李四','111111'), (3,'王五','111111'); SELECT *FROM USER;

      

2.1新建项目

l  新建一个普通的maven项目

l  删除src目录

l  导入依赖

l  <!-- 导入依赖-->
<dependencies>
    <!--mysql驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.47</version>
    </dependency>
    <!-- mybatis-->
    <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.6</version>
    </dependency>
    <!--junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
    </dependency>
</dependencies>

 

2.2 创建一个模块

l  编写mybatis核心配置文件

<?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">



<!--核心配置文件 -->

<configuration>



    <environments default="development">

        <environment id="development">

            <transactionManager type="JDBC"/>

            <dataSource type="POOLED">

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

                <property name="url" value="jdbc:mysql://localhost:3306?serverTimeZone=GMT/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>

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

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

            </dataSource>

        </environment>

    </environments>

<mappers>

    <mapper resource="com/luo/dao/UsersMapper.xml" />

</mappers>

</configuration>

l  编写mybatis工具类

l  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.InputStream;



//sqlSessionFactory --> sqlSession

public class MybatisUtils {



    public static SqlSessionFactory sqlSessionFactory=null;



    static {



        InputStream inputStream = null;

        try {

            //使用Mybatis第一步：获取sqlSessionFactory对象

            String resource = "mybatis-config.xml";

            inputStream = Resources.getResourceAsStream(resource);

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        } catch (IOException e) {

            e.printStackTrace();

        }



    }

    //诚然，这种方式能够正常工作，对使用旧版本 MyBatis 的用户来说也比较熟悉。但现在有了一种更简洁的方式——使用和指定语句的参数和返回值相匹配的接口（比如 BlogMapper.class），

    // 现在你的代码不仅更清晰，更加类型安全，还不用担心可能出错的字符串字面值以及强制类型转换。

    public static SqlSession getSqlSession(){



        return sqlSessionFactory.openSession();

    }

2.3编写代码

l  实体类

l  public class Users {

    private int id;

    private String name;

    private String pwd;



    public Users() {

    }



    public Users(int id, String name, String pwd) {

        this.id = id;

        this.name = name;

        this.pwd = pwd;

    }



    public int getId() {

        return id;

    }



    public void setId(int id) {

        this.id = id;

    }



    public String getName() {

        return name;

    }



    public void setName(String name) {

        this.name = name;

    }



    public String getPwd() {

        return pwd;

    }



    public void setPwd(String pwd) {

        this.pwd = pwd;

    }

}

 

l  Dao接口

l  import com.luo.pojo.Users;

import java.util.List;



public interface UsersDao {

    List<Users> getUserList();

}

 

l  接口实现类

l  <?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">

<!-- 绑定对应的Dao接口-->

<mapper namespace="com.luo.dao.UsersDao">



    <!-- select查询语句-->

    <select id="getUserList" resultType="com.luo.pojo.Users">

        select *from mybatis.user

    </select>

</mapper>

2.4 测试

       Junit测试

              注意点：org.apache.ibatis.binding.BindingException: Type interface com.luo.dao.UsersDao is not known to the MapperRegistry.

 

        @Test

public void test(){

    

    //第一步：获得SqlSession对象

    SqlSession sqlSession = MybatisUtils.getSqlSession();

    //方式一：

    UsersDao usersDao = sqlSession.getMapper(UsersDao.class);

    List<Users> userList = usersDao.getUserList();

    for (Users user:userList) {

        System.out.print(user.getId()+"\t"+user.getName()+"\t"+user.getPwd()+"\n");



    }

    //关闭

    sqlSession.close();



}