MyBatis入门案例

0.数据库准备

CREATE TABLE USER(
id INT(11) NOT NULL AUTO_INCREMENT,
username VARCHAR(32),
birthday DATETIME,
sex CHAR(1),
address VARCHAR(256),
PRIMARY KEY(id)
);
INSERT INTO USER(id,username,birthday,sex,address) VALUES(41,"老王",'2018-2-27','男',"北京市顺义区");

INSERT INTO USER(id,username,birthday,sex,address) VALUES(42,"小二王",'2018-3-2','女',"北京市金燕龙");

INSERT INTO USER(id,username,birthday,sex,address) VALUES(43,"小二王",'2018-3-4','女',"北京市金燕龙");

INSERT INTO USER(id,username,birthday,sex,address) VALUES(44,"老王",'2018-3-7','男',"北京");

INSERT INTO USER(id,username,birthday,sex,address) VALUES(45,"小马宝莉",'2018-3-8','女',"北京修正");

1.导入jar包依赖

<?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.heng</groupId>
    <artifactId>mybatis-01</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

2.编写实体类

package com.ghh.domain;

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 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 + '\'' +
                '}';
    }
}

3.编写接口

package com.ghh.dao;

import com.ghh.domain.User;

import java.util.List;

/**
 * 用户的持久层接口
 */
public interface UserDao {
    List<User> findAll();
}

4.编写核心配置文件

<?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">
<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/mybatis_heima"/>
                <property name="username" value="root"/>
                <property name="password" value="123"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/ghh/dao/UserDao.xml"/>
    </mappers>
</configuration>

5.编写接口对应的配置文件

<?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.ghh.dao.UserDao">
    <select id="findAll" resultType="com.ghh.domain.User">
        select * from user;
    </select>
</mapper>

6.编写测试类

package com.ghh.test;


import com.ghh.dao.UserDao;
import com.ghh.domain.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.IOException;
import java.io.InputStream;
import java.util.List;

public class MybatisTest {
    public static void main(String[] args) throws IOException {
        //1.读取配置文件
        InputStream inputStream =  Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = builder.build(inputStream);
        //3.使用工厂创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //4.使用SqlSession创建Dao接口的代理对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        //5.使用代理对象执行方法
        List<User> users = mapper.findAll();
        for(User user:users){
            System.out.println(user);
        }
        //6.释放资源
        sqlSession.close();
    }
}