新手的mybatis的入门案例

mybatis的入门案例

mybatis环境搭建

1. 使用IDEA新建Maven工程，网上教程很多不再赘述，下面放上相关的教程

IDEA中创建maven web项目的详细部署

2. 新建数据库表

CREATE TABLE `user` (
  `id` int(11) NOT NULL auto_increment,
  `username` varchar(32) NOT NULL COMMENT '用户名称',
  `birthday` datetime default NULL COMMENT '生日',
  `sex` char(1) default NULL COMMENT '性别',
  `address` varchar(256) default NULL COMMENT '地址',
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8; 
//人员信息
insert  into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (1,'小白','2018-02-27 17:47:08','男','北京'),(2,'小红','2018-03-02 15:09:37','女','成都'),(3,'小绿','2018-03-04 11:34:34','女','上海'),(4,'小黑','2018-03-04 12:04:06','男','武汉'),(5,'小紫','2018-03-07 17:37:26','男','北京'),(6,'小蓝','2018-03-08 11:44:00','女','北京');

3. 在pom.xml文件中分别添加Mybatis、mysql、junit、log4j的依赖

    <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.13</version>
        </dependency>

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

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

4. 在main/java下新建实体类User

public class User implements Serializable {
    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String 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 + '\'' +
                '}';
    }
}

5. 编写持久层接口 UserDao

public interface UserDao {

    //查询所有用户
    List<User> findAll();
}

6. 编写持久层接口的映射文件UserDao.xml

<?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="xyz.nandu.dao.UserDao">
    <!-- 配置查询所有操作 -->
    <select id="findAll" resultType="xyz.nandu.domain.User">
        select * from user
    </select>
</mapper>

7. 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/mybatisdemo"/>
                <property name="username" value="root"/>
                <property name="password" value="x5"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 告知mybatis映射配置的位置 -->
    <mappers>
        <mapper resource="com/itheima/dao/IUserDao.xml"/>
    </mappers>
</configuration>

1. 编写测试类MybatisTest

public class MybatisTest {
    public static void main(String[] args) throws IOException {
        //读取配置文件
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建SqlSessionFactory的构建者对象
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //使用构建者创建工厂对象SqlSessionFactory
        SqlSessionFactory factory = builder.build(in);
        //使用SqlSessionFactory生产SqlSession对象
        SqlSession session = factory.openSession();
        //使用SqlSession创建dao接口的代理对象
        UserDao userDao = session.getMapper(UserDao.class);
        //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); }
        //释放资源
        session.close();
        in.close();
    }
}

总结

1. 环境搭建步骤

   • 创建Maven工程并导入坐标
   • 创建实体类接口
   • 创建Dao接口
   • 创建Mybatis主配置文件
   • 创建映射配置文件

2. 注意事项：

   • mybatis的映射配置文件位置必须和dao接口的包结构相同
   • 映射配置文件的操作配置，id属性取值必须是dao接口的方法名

至此，mybatis入门案例完成！