Mybatis入门环境搭建和入门案列

最新推荐文章于 2024-07-03 23:39:30 发布

原创最新推荐文章于 2024-07-03 23:39:30 发布 · 150 阅读

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#mybatis

本文详细介绍了如何使用MyBatis框架进行数据库操作，包括环境搭建、实体类创建、配置文件设置、基本CRUD操作及注解配置等核心内容。

MyBatis
ORMapping: Object Relationship Mapping 对象关系映射
对象指⾯向对象
关系指关系型数据库
Java 到 MySQL 的映射，开发者可以以⾯向对象的思想来管理数据库。

1. 新建Maven工程，(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.suse</groupId>
    <artifactId>day01_eesy_mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.5</version>
    </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

</dependencies>
</project>

2.新建数据表数据库名为demo

DROP TABLE IF EXISTS `user`;

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;



insert  into `user`(`id`,`username`,`birthday`,`sex`,`address`) values (41,'老王','2018-02-27 17:47:08','男','北京'),(42,'小二王','2018-03-02 15:09:37','女','北京金燕龙'),(43,'小二王','2018-03-04 11:34:34','女','北京金燕龙'),(45,'胖娃','2018-03-04 12:04:06','男','北京金燕龙'),(46,'老王','2018-03-07 17:37:26','男','北京'),(48,'廋娃','2018-03-08 11:44:00','女','北京修正');

建立数据表对应的实体类

package com.suse;

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

在resourse下创建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">
<configuration>
    <!--配置环境-->
    <environments default="mysql">
        <!--配置mysql-->
        <environment id="mysql">
            <!--配置事务的类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源(连接池)-->
            <dataSource type="POOLED">
                <!--配置连接数据库的4个基本信息-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/Demo"/><!--数据库名称-->
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <!--指定映射配置文件，每个dao单独的文件-->
    <mappers>
        <mapper resource="com/suse/dao/IUserDao.xml"/> <!--在resource下新建-->
    </mappers>

</configuration>

在resource下创建IUserDao.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="com.suse.dao.IUserDao">
    <!--配置查询所有 id为方法的名字-->
    <select id="findAll" resultType="com.suse.User">  <!--返回的是实体类，注意路径-->
        select * from user
    <!--
    </select>
    <insert id="save" parameterType="com.suse.dao.IUserDao">
        insert into user (id,username,birthday,sex,address) values(#{id},#{username},#{birthday},#{sex},#{address})
    </insert>
    -->

</mapper>

调试类中运行

package com.suese.test;


import com.suse.dao.IUserDao;
import com.suse.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");//注意Resources的包org.apache.ibatis.io.Resources,抛出异常
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工程生成SqlSession对象
        SqlSession session = factory.openSession();
        //4.使用SqlSession创建Dao接口的代理
        IUserDao userDao = session.getMapper(IUserDao.class);
        //5.使用代理对象执行方法
        List<User> users = userDao.findAll();
        for (User user:users){
            System.out.println(user);
        }
        //6.释放对象
        session.close();
        in.close();
    }
}

执行插入操作

IUserDao 接口中
void saveUser(User user);
IUserDao.xml配置

<!--保存用户-->
    <insert id="saveUser" parameterType="com.itheima.domain.User">
        insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday});
        <!--javaweb中使用？进行占位，mybatis则使用#{}进行占位-->
    </insert>

测试单元

public class MybatisTest01 {

    /**
     * 测试保存对象
     */
    @Test
    public void testSave() throws Exception{
        User user = new User();
        user.setUsername("mybatis save");
        user.setAddress("3306");
        user.setSex("男");
        user.setBirthday(new Date());

        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产的SqlSession对象
        SqlSession session = factory.openSession();
        //4.使用SqlSession对象创建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 保存

		//数据库执行操作
        userDao.saveUser(user);
        session.commit();
        
        //6.释放资源 
        session.close();
        in.close();

    }
}

使用注解配置Insert

public interface IUserDao {
    @Insert("insert into user(username,address,sex,birthday)"+"values(#{username},#{address},#{sex},#{birthday})")
    void saveUser(User user);
}

SqlMapConfig配置

 <mappers>
        <mapper class="com.itheima.dao.IUserDao"></mapper><!--与dao层的包结构保持一致 创建文件目录-->
    </mappers>

测试单元

public class MybatisTest01 {

    /**
     * 测试保存对象
     */
    @Test
    public void testSave() throws Exception{
        User user = new User();
        user.setUsername("mybatis save1");
        user.setAddress("3306");
        user.setSex("男");
        user.setBirthday(new Date());

        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产的SqlSession对象
        SqlSession session = factory.openSession();
        //4.使用SqlSession对象创建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 保存    操作数据库的方法
        userDao.saveUser(user);
        session.commit();
        
        //6.释放资源
        session.close();
        in.close();

    }
}

2.数据库操作方法

2.1 select

public interface IUserDao {
    @Select("select * from user")
    List<User> findAll();
}

<mapper namespace="com.itheima.dao.IUserDao">
   <!--配置查询所有  id为方法名称-->
   <select id="findAll" resultType="com.itheima.domain.User">
       select * from user
   </select>
    /mapper>

selsect关键代码

List<User> users = userDao.findAll();
for (User user : users){
    System.out.println(user);
}

2.2 insert

public interface IUserDao {
    @Insert("insert into user(username,address,sex,birthday)"+"values(#{username},#{address},#{sex},#{birthday})")
    void saveUser(User user);
}

<mapper namespace="com.itheima.dao.IUserDao">
<insert id="saveUser" parameterType="com.itheima.domain.User">
    insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday});
    <!--javaweb中使用？进行占位，mybatis则使用#{}进行占位-->
</insert>
</mapper>

public class MybatisTest01 {

    /**
     * 测试保存对象
     */
    @Test
    public void testSave() throws Exception{
        User user = new User();
        user.setUsername("mybatis save1");
        user.setAddress("3306");
        user.setSex("男");
        user.setBirthday(new Date());

        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产的SqlSession对象
        SqlSession session = factory.openSession();
        //4.使用SqlSession对象创建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 保存
        userDao.saveUser(user);
        session.commit();
        //6.释放资源
        session.close();
        in.close();

    }
}

insert数据库操作关键代码

userDao.saveUser(user);
        session.commit();

2.3 update

void updateUser(User user);

<mapper>
    <update id="updateUser" parameterType="com.itheima.domain.User">
    update  user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday} where id=#{id}
      </update>
 </mapper>

数据库操作关键代码

 userDao.updateUser(user);
        session.commit();

2.4删除操作

void deleteUser(Integer userId);

<mapper>
    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id=#{id}
    </delete>
    </mapper>

@Test
    public void testDelete() throws Exception{
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产的SqlSession对象
        SqlSession session = factory.openSession();
        //4.使用SqlSession对象创建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 保存
        userDao.deleteUser(48);
        session.commit();
        //6.释放资源
        session.close();
        in.close();
    }

userDao.deleteUser(48);
        session.commit();

2.5根据id查找信息

User findById(Integer userid);

<!--根据id查询用户-->
<mapper>
    <select id="findById" parameterType="java.lang.Integer" resultType="com.itheima.domain.User">
        select * from user where id=#{id}
    </select>
    </mapper>

@Test
    public void testFindOne() throws Exception{
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产的SqlSession对象
        SqlSession session = factory.openSession();
        //4.使用SqlSession对象创建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 保存
        User user = userDao.findById(46);
        session.commit();
        System.out.println(user);
        //6.释放资源
        session.close();
        in.close();
    }