MyBatis框架学习（一）

一、搭建MyBatis开发环境

1. 创建maven工程
Groupid:com.chenbin
ArtifactId:mybatis01
Packing:jar

2.添加MyBatis3.4.5坐标
在 pom.xml 文件中添加 Mybatis3.4.5 的坐标，如下：

<dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>

3. 编写User实体类

package com.chenbin.mybatis01.pojo;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {

    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;

    public User(Integer id, String username, Date birthday, String sex, String address) {
        this.id = id;
        this.username = username;
        this.birthday = birthday;
        this.sex = sex;
        this.address = address;
    }

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

4. 编写持久层接口 UserDao

package com.chenbin.mybatis01.dao;

import com.chenbin.mybatis01.pojo.User;

import java.util.List;

public interface UserDao {

    /**
     * 查询所有用户
     * @return
     */
    List<User> findAll();

}

5. 编写持久层接口的映射文件 UserDao.xml
（UseDao.xml和UserDao.java必须在同一个包中）

<?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.chenbin.mybatis01.pojo.User">

    <!-- 配置查询所有操作 -->
    <select id="findAll" resultType="com.itheima.domain.User">
      select * from user
    </select>
    
</mapper>

6. 编写 SqlMapConfig.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>

    <!-- 配置 mybatis 的环境 -->
    <environments default="mysql">
        <!-- 配置 mysql 的环境 -->
        <environment id="mysql">
            <!-- 配置事务的类型 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置连接数据库的信息：用的是数据源(连接池) -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ee50"/>
                <property name="username" value="root"/>
                <property name="password" value="456789"/>
            </dataSource>
        </environment>
    </environments>
    
    <!-- 告知 mybatis 映射配置的位置 -->
    <mappers>
        <mapper resource="com/itheima/dao/IUserDao.xml"/>
    </mappers>

</configuration>

7.编写测试类

package com.chenbin.mybatis01.test;

import com.chenbin.mybatis01.dao.UserDao;
import com.chenbin.mybatis01.pojo.User;
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.InputStream;
import java.util.List;

public class MyBatisTest {

    public static void main(String[] args) throws Exception {
        //1.读取配置文件
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");

        //2.创建 SqlSessionFactory 的构建者对象
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();

        //3.使用构建者创建工厂对象 SqlSessionFactory
        SqlSessionFactory factory = builder.build(in);

        //4.使用 SqlSessionFactory 生产 SqlSession 对象
        SqlSession session = factory.openSession();

        //5.使用 SqlSession 创建 dao 接口的代理对象
        UserDao userDao = session.getMapper(UserDao.class);

        //6.使用代理对象执行查询所有方法
        List<User> users = userDao.findAll();

        for (User user : users) {
            System.out.println(user);
        }
        
        //7.释放资源
        session.close();
        in.close();
    }
}

文件结构：