MyBatis入门案例01

MyBatis基于配置的入门案例

数据库表

在IDEA中创建maven项目

整体架构

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.uek</groupId>
    <artifactId>mybatis01-study01-configuration</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--打包方式-->
    <packaging>jar</packaging>

    <dependencies>
        <!--导入MyBatis的坐标-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <!--导入MySQL-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
        </dependency>

        <!--日志-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

        <!--单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>

    </dependencies>

MyBatis的主配置文件

SqlMapConfig.xml

<?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">
<!--MyBatis的主配置文件-->
<configuration>
    <!--配置环境-->
    <environments default="mysql">
        <!--配置mysql的环境-->
        <environment id="mysql">
            <!--配置事务的类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源(也叫连接池)-->
            <dataSource type="POOLED">
                <!--配置连接数据的四个基本信息-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <!--指定映射文件的位置，映射配置文件指的是每个dao独立的配置文件-->
    <mappers>
        <mapper resource="com/uek/dao/IUserDao.xml"></mapper>
    </mappers>

</configuration>

dao层接口

/**
 * 用户的持久成接口
 */
public interface IUserDao {
    //查询所有操作
    List<User> findAll();
}

实体类

public class User implements Serializable {

    //表中的列名，一一对应
    private int id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;

    public int getId() {
        return id;
    }

    public void setId(int 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 + '\'' +
                '}';
    }
}

接口配置 IUserDao.xml

注意：在resource目录下新建包时一级一级的建立
必须和dao层的接口的包名一致。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.uek.dao.IUserDao">
<!--配置查询所有-->
    <select id="findAll" resultType="com.uek.domain.User">
        select * from user
    </select>
</mapper>

测试类

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工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory build = builder.build(in);

        //3.使用工厂生产Session对象
        SqlSession session = build.openSession();

        //4.使用SqlSession创建Dao接口的代理对象
        IUserDao userDao = session.getMapper(IUserDao.class);

        //5.使用代理对象执行方法
        List<User> all = userDao.findAll();
        for (User user : all) {
            System.out.println(user);
        }

        //6.释放资源
        session.close();
        in.close();
    }
}