【编程不良人】MyBatis从入门到精通学习笔记01---IDEA使用Maven项目搭建MyBatis操作环境

喜欢ヅ旅行 2023-10-09 13:59 46阅读 0赞

**配套视频：**[【编程不良人】Mybatis 从入门到精通\_哔哩哔哩\_bilibili][Mybatis _bilibili]

**参考链接：**[从前慢-Mybatis\_unique\_perfect的博客-CSDN博客][-Mybatis_unique_perfect_-CSDN]

### 1.引言 ###

Mybatis是一个基于java语言的持久层的框架，主要用来简化数据库的访问操作，内部封装了原来的jdbc代码，替换了原有项目开发中的jdbc技术，它可以自动完成对象与关系的映射(ORM)，极大地简化了我们的开发，提高了开发效率。

MyBatis官方网址：[mybatis – MyBatis 3 | Introduction][mybatis _ MyBatis 3 _ Introduction]

MyBatis中文网： [MyBatis中文网][MyBatis]

### 2.JDBC存在的问题 ###

1) 大量的代码冗余 (处理结果集的时候存在大量的代码冗余)

2) 不能完成数据库和实体的自动转换 (需要手动封装实体，不能自动封装实体类)

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16][]

> 实体与数据库之间的转换需要通过setXxx或者构造方法完成

### 3.Mybatis框架的开发思路 ###

需要2个配置文件：

*  mybatis-config.xml：存储数据库连接相关参数，获取连接对象
 *  mapper映射文件：因为映射文件中的id代表方法名，是识别方法的唯一标识，所以注意DAO中的方法名不能相同，不能重载。

###  ###

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

### 4.使用IDEA中的Maven进行MyBatis环境搭建 ###

**配套视频：**[【编程不良人】Mybatis 从入门到精通\_哔哩哔哩\_bilibili][Mybatis _bilibili 1]

（视频中为利用Eclipse进行Mybatis环境搭建，此处参考下面链接使用IDEA进行Mybatis环境搭建）

**参考链接：**

*  [使用IDEA Maven搭建mybatis环境 - wangf98 - 博客园][IDEA Maven_mybatis_ - wangf98 -]
 *  [Idea2019搭建Mybatis框架环境demo\_夜空中的小轩的博客-CSDN博客\_idea搭建mybatis环境][Idea2019_Mybatis_demo_-CSDN_idea_mybatis]

**项目整体结构如下：**

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16 2][]

**1.新建Maven-archetype-webapp项目，命名为mybatis01**

**![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16 3][]**

**2.src---main路径下新建java、resources文件夹**

**![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16 4][]**

**3.pom.xml导入相关依赖，刷新Maven**

<?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>org.example</groupId>
        <artifactId>mybatis01</artifactId>
        <version>1.0-SNAPSHOT</version>
        <packaging>war</packaging>
      
        <name>mybatis01 Maven Webapp</name>
        
        <url>http://www.example.com</url>
      
        <properties>
          <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <maven.compiler.source>1.7</maven.compiler.source>
          <maven.compiler.target>1.7</maven.compiler.target>
        </properties>
      
        <dependencies>
          
          <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
          </dependency>
          
          
          <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.6</version>
          </dependency>
          
          
          <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
          </dependency>
          <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>compile</scope>
          </dependency>
        </dependencies>
      
        <build>
          <finalName>mybatis01</finalName>
          <pluginManagement>
            <plugins>
              <plugin>
                <artifactId>maven-clean-plugin</artifactId>
                <version>3.1.0</version>
              </plugin>
              
              <plugin>
                <artifactId>maven-resources-plugin</artifactId>
                <version>3.0.2</version>
              </plugin>
              <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
              </plugin>
              <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.22.1</version>
              </plugin>
              <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.2</version>
              </plugin>
              <plugin>
                <artifactId>maven-install-plugin</artifactId>
                <version>2.5.2</version>
              </plugin>
              <plugin>
                <artifactId>maven-deploy-plugin</artifactId>
                <version>2.8.2</version>
              </plugin>
            </plugins>
          </pluginManagement>
        </build>
      </project>

**4.利用SQLyog创建数据库（mybatis）、表（user）、新增数据**

**![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16 5][]**

![a11c13dbef7a450ca704971ba6e6df8a.png][]

**5.在IDEA java路径下新建entity包、service包**

（1）entity包下新建与表user对应的实体类User，并添加get、set、toString方法

package entity;
      
      /**
       * @ClassName User
       * @Description 用户实体类，对应mybatis数据库中的user表
       * @Author Jiangnan Cui
       * @Date 2022/4/5 10:42
       * @Version 1.0
       */
      public class User {
          private int uid;
          private String uname;
          private int uage;
      
          public int getUid() {
              return uid;
          }
      
          public void setUid(int uid) {
              this.uid = uid;
          }
      
          public String getUname() {
              return uname;
          }
      
          public void setUname(String uname) {
              this.uname = uname;
          }
      
          public int getUage() {
              return uage;
          }
      
          public void setUage(int uage) {
              this.uage = uage;
          }
      
          @Override
          public String toString() {
              return "User{" +
                      "uid=" + uid +
                      ", uname='" + uname + '\'' +
                      ", uage=" + uage +
                      '}';
          }
      }

（2）在service包下新建接口UserService，编写findById方法，不用编写对应的实现类

package service;
      
      import entity.User;
      
      /**
       * @ClassName UserService
       * @Description TODO
       * @Author Jiangnan Cui
       * @Date 2022/4/5 11:56
       * @Version 1.0
       */
      public interface UserService {
          User findById(int id);
      }

**6.在resources路径下新建mapper文件夹，添加mapper映射文件UserMapper.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="entity.User">
          
          <select id="findById" parameterType="int" resultType="entity.User">
              select * from user where uid = #{id}
          </select>
      </mapper>

**7.在resources路径下新建mybatis配置文件mybatis-config.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>
          
          <environments default="development">
              
              <environment id="development">
                  
                  <transactionManager type="JDBC"/>
                  
                  
                  <dataSource type="POOLED">
                      <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                      <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&useSSL=false"/>
                      <property name="username" value="root"/>
                      <property name="password" value="123456"/>
                  </dataSource>
              </environment>
          </environments>
      
          
          <mappers>
              <mapper resource="mapper/UserMapper.xml"/>
          </mappers>
          
      </configuration>

**8.测试Mybatis环境是否搭建成功，在java路径下新建test包，包中编写单元测试类TestMyBatis**

package test;
      
      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.io.Reader;
      import java.sql.SQLException;
      
      /**
       * @ClassName TestMyBatis
       * @Description 测试MyBatis环境是否搭建成功
       * @Author Jiangnan Cui
       * @Date 2022/4/5 17:45
       * @Version 1.0
       */
      public class TestMyBatis {
          public static void main(String[] args) {
              //MyBatis读取配置文件的方式
              //InputStream is = TestMyBatis.class.getResourceAsStream("mybatis-config.xml");
              Reader reader = null;
              try {
                  reader = Resources.getResourceAsReader("mybatis-config.xml");
              } catch (IOException e) {
                  e.printStackTrace();
              }
              //创建SQLSessionFactory对象实例
              SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
              //获取Session, session中包含connection
              SqlSession session = sessionFactory.openSession();
              System.out.println(session);
              try {
                  //一般不从session中获取connection
                  session.getConnection().commit();
              } catch (SQLException e) {
                  e.printStackTrace();
              }
          }
      }

**输出结果不报错，表示环境搭建成功：**

org.apache.ibatis.session.defaults.DefaultSqlSession@6e3c1e69
      Tue Apr 05 18:04:27 CST 2022 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

**9.test中编写单元测试类UserTest**

package test;
      
      import entity.User;
      import org.apache.ibatis.io.Resources;
      import org.apache.ibatis.session.*;
      import org.junit.Test;
      
      import java.io.IOException;
      import java.io.Reader;
      import java.sql.Connection;
      
      /**
       * @ClassName UserTest
       * @Description 单元测试
       * @Author Jiangnan Cui
       * @Date 2022/4/5 11:58
       * @Version 1.0
       */
      public class UserTest {
          @Test
          public void userFindByIdTest() {
              //配置文件名称
              String resources = "mybatis-config.xml";
              //创建流
              Reader reader = null;
              try {
                  //使用MyBatis提供的Resources类加载mybatis的配置文件到reader对象中
                  reader= Resources.getResourceAsReader(resources);
              } catch (IOException e) {
                  e.printStackTrace();
              }
              //初始化mybatis，创建sqlSessionFactory类的实例
              SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
              //创建session实例
              SqlSession session= sessionFactory.openSession();
              //传入参数查询，返回结果
              User user = session.selectOne("findById",1);
              System.out.println(user);
              //关闭session
              session.close();
          }
      }

**测试结果如下：**

Tue Apr 05 13:35:42 CST 2022 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
      User{uid=1, uname='zhangsan', uage=20}

### 5. 代码结构调整 ###

#### 5.1 建表 ####

-- 新建表
     DROP TABLE IF EXISTS `t_user`;
     CREATE TABLE `t_user` (
       `id` int(11) NOT NULL auto_increment COMMENT '用户ID',
       `name` varchar(32) NOT NULL COMMENT '用户名',
       `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;
     
     
     -- 插入数据
     insert  into `t_user`(`id`,`name`,`birthday`,`sex`,`address`) values
      (1,'老王','2018-02-27 17:47:08','男','北京'),
      (2,'小二王','2018-03-02 15:09:37','女','北京金燕龙'),
      (3,'小二王','2018-03-04 11:34:34','女','北京金燕龙'),
      (4,'传智播客','2018-03-04 12:04:06','男','北京金燕龙'),
      (5,'老王','2018-03-07 17:37:26','男','北京'),
      (6,'小马宝莉','2018-03-08 11:44:00','女','北京修正');

#### 5.2 新建maven项目并在pom.xml中引入依赖 ####

*  **pom.xml**

<dependency>
       <groupId>org.mybatis</groupId>
       <artifactId>mybatis</artifactId>
       <version>3.4.1</version>
     </dependency>
     
     
     <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>5.1.38</version>
     </dependency>
     
     
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.11</version>
       <scope>test</scope>
     </dependency>
     
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.12</version>
       <scope>compile</scope>
     </dependency>

**刷新Maven！**

#### 5.3 开发实体类(entity) ####

*  **User.java**

package com.study.entity;
     
     import java.io.Serializable;
     import java.util.Date;
     
     /**
      * @ClassName User
      * @Description 用户实体类，对应mybatis数据库中表t_user
      * @Author Jiangnan Cui
      * @Date 2022/8/13 17:39
      * @Version 1.0
      */
     public class User implements Serializable {
         private Integer id;
         private String name;
         private Date birthday;
         private Character sex;
         private String address;
     
         public User() {
         }
     
         public User(Integer id, String name, Date birthday, Character sex, String address) {
             this.id = id;
             this.name = name;
             this.birthday = birthday;
             this.sex = sex;
             this.address = address;
         }
     
         public Integer getId() {
             return id;
         }
     
         public void setId(Integer id) {
             this.id = id;
         }
     
         public String getName() {
             return name;
         }
     
         public void setUsername(String name) {
             this.name = name;
         }
     
         public Date getBirthday() {
             return birthday;
         }
     
         public void setBirthday(Date birthday) {
             this.birthday = birthday;
         }
     
         public Character getSex() {
             return sex;
         }
     
         public void setSex(Character 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 +
                     ", name='" + name + '\'' +
                     ", birthday=" + birthday +
                     ", sex=" + sex +
                     ", address='" + address + '\'' +
                     '}';
         }
     }

#### 5.4 开发持久层(Dao) ####

*  **IUserDao.java**

package com.study.dao;
     
     import com.study.entity.User;
     
     import java.util.List;
     
     /**
      * @ClassName IUserDao
      * @Description 用户持久层接口UserDao
      * @Author Jiangnan Cui
      * @Date 2022/8/13 17:43
      * @Version 1.0
      */
     public interface IUserDao {
         /**
          * @MethodName findAll
          * @Description 查询所有用户
          * @return: java.util.List<com.study.entity.User>
          * @Author Jiangnan Cui
          * @Date 17:44 2022/8/13
          */
         List<User> findAll();
     }

#### 5.5 开发mapper映射文件 ####

*  **IUserDaoMapper.xml**

#### 5.6 开发mybatis主配置文件 ####

*  **mybatis-config.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>
         
         <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?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&useSSL=false"/>
                     <property name="username" value="root"/>
                     <property name="password" value="root"/>
                 </dataSource>
             </environment>
         </environments>
     
         
         <mappers>
             
             <mapper resource="com/study/mapper/IUserDaoMapper.xml"/>
         </mappers>
     </configuration>

#### 5.7 开发测试类 ####

*  **IUserDaoTest.java**

**测试结果：**

user = User{id=1, name='老王', birthday=Tue Feb 27 17:47:08 CST 2018, sex=男, address='北京'}
     user = User{id=2, name='小二王', birthday=Fri Mar 02 15:09:37 CST 2018, sex=女, address='北京金燕龙'}
     user = User{id=43, name='小二王', birthday=Sun Mar 04 11:34:34 CST 2018, sex=女, address='北京金燕龙'}
     user = User{id=45, name='传智播客', birthday=Sun Mar 04 12:04:06 CST 2018, sex=男, address='北京金燕龙'}
     user = User{id=46, name='老王', birthday=Wed Mar 07 17:37:26 CST 2018, sex=男, address='北京'}
     user = User{id=48, name='小马宝莉', birthday=Thu Mar 08 11:44:00 CST 2018, sex=女, address='北京修正'}

#### 5.8 最终项目结构 ####

![243524ce3afa4d32a4a06114531228cb.png][]

#### 5.9 测试增删改基本操作 ####

**具体增删改细节参见：**[【编程不良人】MyBatis从入门到精通学习笔记02-Mybatis中增删改查使用\_Coder\_Cui的博客-CSDN博客][MyBatis_02-Mybatis_Coder_Cui_-CSDN]

*  **IUserDao.java**

package com.study.dao;
     
     import com.study.entity.User;
     import org.apache.ibatis.annotations.Param;
     
     import java.util.List;
     
     /**
      * @ClassName IUserDao
      * @Description TODO
      * @Author Jiangnan Cui
      * @Date 2022/8/13 20:16
      * @Version 1.0
      */
     public interface IUserDao {
         /**
          * @MethodName findAll
          * @Description 查询所有
          * @return: java.util.List<com.study.entity.User>
          * @Author Jiangnan Cui
          * @Date 20:31 2022/8/13
          */
         List<User> findAll();
     
         /**
          * @MethodName findById
          * @Description 根据Id查询
          * @param: id
          * @return: com.study.entity.User
          * @Author Jiangnan Cui
          * @Date 20:32 2022/8/13
          */
         User findById(Integer id);
     
         /**
          * @MethodName findByIdAndName
          * @Description 多参数查询
          * @param: id
          * @param: name
          * @return: com.study.entity.User
          * @Author Jiangnan Cui
          * @Date 20:37 2022/8/13
          */
         User findByIdAndName(@Param("id") Integer id,@Param("name")String name);
     
         /**
          * @MethodName add
          * @Description 新增用户
          * @param: user
          * @return: java.lang.Integer
          * @Author Jiangnan Cui
          * @Date 20:45 2022/8/13
          */
         Integer add(User user);
     
         /**
          * @MethodName deleteById
          * @Description 根据id删除用户
          * @param: id
          * @return: java.lang.Integer
          * @Author Jiangnan Cui
          * @Date 21:05 2022/8/13
          */
         Integer deleteById(Integer id);
     
         /**
          * @MethodName updateById
          * @Description 根据id修改用户
          * @param: id
          * @return: java.lang.Integer
          * @Author Jiangnan Cui
          * @Date 21:09 2022/8/13
          */
         Integer update(User user);
     }

*  **IUserDaoMapper.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.study.dao.IUserDao">
         
       <select id="findAll" resultType="com.study.entity.User">
         select
             id,name,birthday,sex,address
         from t_user
       </select>
     
         
         <select id="findById" parameterType="Integer" resultType="com.study.entity.User">
             select
                 id,name,birthday,sex,address
             from t_user
             where id=#{id}
         </select>
     
         
         <select id="findByIdAndName" resultType="com.study.entity.User">
             select
                 id,name,birthday,sex,address
             from t_user
             where id=#{id} and name=#{name}
         </select>
     
         
         <insert id="add" parameterType="com.study.entity.User" >
             insert into t_user values(#{id},#{name},#{birthday},#{sex},#{address})
         </insert>
     
         
         <delete id="deleteById" parameterType="Integer" >
             delete from t_user where id=#{id}
         </delete>
     
         
         <update id="update" parameterType="com.study.entity.User">
             update t_user set name=#{name},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id}
         </update>
     </mapper>

*  **IUserDaoTest.java**

package com.study.test;
     
     import com.study.dao.IUserDao;
     import com.study.entity.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 org.junit.Test;
     
     import java.io.IOException;
     import java.io.InputStream;
     import java.util.Date;
     import java.util.List;
     
     /**
      * @ClassName IUserDaoTest
      * @Description TODO
      * @Author Jiangnan Cui
      * @Date 2022/8/13 20:18
      * @Version 1.0
      */
     public class IUserDaoTest {
         /**
          * @MethodName findAllTest
          * @Description 测试查询所有
          * @Author Jiangnan Cui
          * @Date 20:59 2022/8/13
          */
         @Test
         public void findAllTest() throws IOException {
             InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
             SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
             SqlSessionFactory factory = builder.build(is);
             SqlSession sqlSession = factory.openSession();
             IUserDao userDao = sqlSession.getMapper(IUserDao.class);
             List<User> userList = userDao.findAll();
             for (User user : userList) {
                 System.out.println("user = " + user);
             }
             //释放资源
             sqlSession.close();
             is.close();
         }
     
         /**
          * @MethodName findByIdTest
          * @Description 根据id查询
          * @Author Jiangnan Cui
          * @Date 20:59 2022/8/13
          */
         @Test
         public void findByIdTest() throws IOException {
             InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
             SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
             SqlSessionFactory factory = builder.build(is);
             SqlSession sqlSession = factory.openSession();
             IUserDao userDao = sqlSession.getMapper(IUserDao.class);
             User user = userDao.findById(1);
             System.out.println("user = " + user);
         }
     
         /**
          * @MethodName findByIdAndNameTest
          * @Description 根据id和name查询
          * @Author Jiangnan Cui
          * @Date 20:59 2022/8/13
          */
         @Test
         public void findByIdAndNameTest() throws IOException {
             InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
             SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
             SqlSessionFactory factory = builder.build(is);
             SqlSession sqlSession = factory.openSession();
             IUserDao userDao = sqlSession.getMapper(IUserDao.class);
             User user = userDao.findByIdAndName(2, "小二王");
             System.out.println("user = " + user);
         }
     
         /**
          * @MethodName addTest
          * @Description 新增用户
          * @Author Jiangnan Cui
          * @Date 21:00 2022/8/13
          */
         @Test
         public void addTest() throws IOException {
             SqlSession sqlSession = null;
             try {
                 InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
                 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
                 SqlSessionFactory factory = builder.build(is);
                 sqlSession = factory.openSession();
                 IUserDao userDao = sqlSession.getMapper(IUserDao.class);
                 Integer n = userDao.add(new User(9, "皮卡丘", new Date(), '女', "黑龙江"));
                 System.out.println("受影响的行数 = " + n);
                 mybatis执行增删改时默认事务提交方式是手动的（setAutoCommit(false)），此处需要进行提交
                 sqlSession.commit();//新增需要提交事务
             } catch (IOException e) {
                 e.printStackTrace();
                 sqlSession.rollback();;
             }
         }
     
         /**
          * @MethodName deleteByIdTest
          * @Description 根据id删除
          * @Author Jiangnan Cui
          * @Date 21:11 2022/8/13
          */
         @Test
         public void deleteByIdTest() {
             SqlSession sqlSession = null;
             try {
                 InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
                 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
                 SqlSessionFactory factory = builder.build(is);
                 sqlSession = factory.openSession();
                 IUserDao userDao = sqlSession.getMapper(IUserDao.class);
                 Integer n = userDao.deleteById(7);
                 System.out.println("受影响的行数 = " + n);
                 //mybatis执行增删改时默认事务提交方式是手动的（setAutoCommit(false)），此处需要进行提交
                 sqlSession.commit();//新增需要提交事务
             } catch (IOException e) {
                 e.printStackTrace();
                 sqlSession.rollback();
             }
         }
     
         /**
          * @MethodName updateByIdTest
          * @Description 根据id修改
          * @Author Jiangnan Cui
          * @Date 21:11 2022/8/13
          */
         @Test
         public void updateTest() {
             SqlSession sqlSession = null;
             try {
                 InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
                 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
                 SqlSessionFactory factory = builder.build(is);
                 sqlSession = factory.openSession();
                 IUserDao userDao = sqlSession.getMapper(IUserDao.class);
                 Integer n = userDao.update(new User(3, "喜洋洋", new Date(), '男', "羊村"));
                 System.out.println("受影响的行数 = " + n);
                 //mybatis执行增删改时默认事务提交方式是手动的（setAutoCommit(false)），此处需要进行提交
                 sqlSession.commit();//新增需要提交事务
             } catch (IOException e) {
                 e.printStackTrace();
                 sqlSession.rollback();
             }
         }
     }

#### 5.10 MybatisUtil封装 ####

*  **MyBatisUtil.java**

package com.study.utils;
     
     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;
     
     /**
      * @ClassName MybatisUtil
      * @Description TODO
      * @Author Jiangnan Cui
      * @Date 2022/8/13 21:22
      * @Version 1.0
      */
     public class MybatisUtil {
         //声明工厂
         private static SqlSessionFactory sqlSessionFactory;
     
         //使用ThreadLocal保证service与dao层session一致
         private static final ThreadLocal<SqlSession> t = new ThreadLocal<>();
     
         //静态块，保证只加载一次
         static {
             try {
                 InputStream is = Resources.getResourceAsStream("com/study/config/mybatis-config.xml");
                 sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
             } catch (IOException e) {
                 throw new RuntimeException(e);
             }
         }
     
         /**
          * @MethodName getSession
          * @Description 获得SqlSession对象
          * @return: org.apache.ibatis.session.SqlSession
          * @Author Jiangnan Cui
          * @Date 21:31 2022/8/13
          */
         public static SqlSession getSession(){
             SqlSession sqlSession = t.get();
             if(sqlSession==null){
                 sqlSession = sqlSessionFactory.openSession();
                 t.set(sqlSession);
             }
             return sqlSession;
         }
     
         /**
          * @MethodName close
          * @Description 关闭SqlSession对象
          * @Author Jiangnan Cui
          * @Date 21:34 2022/8/13
          */
         public static void close(){
             SqlSession sqlSession = t.get();
             if(sqlSession!=null){
                 sqlSession.close();
                 t.remove();
             }
         }
     
         /**
          * @MethodName commit
          * @Description 提交事务
          * @Author Jiangnan Cui
          * @Date 21:35 2022/8/13
          */
         public static void commit(){
             getSession().commit();
             close();
         }
     
         /**
          * @MethodName rollback
          * @Description 回滚事务
          * @Author Jiangnan Cui
          * @Date 21:36 2022/8/13
          */
         public static void rollback(){
             getSession().rollback();
             close();
         }
     }

*  **IUserDaoTest2.java**

package com.study.test;
     
     import com.study.dao.IUserDao;
     import com.study.entity.User;
     import com.study.utils.MybatisUtil;
     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 org.junit.Test;
     
     import java.io.IOException;
     import java.io.InputStream;
     import java.util.Date;
     import java.util.List;
     
     /**
      * @ClassName IUserDaoTest
      * @Description TODO
      * @Author Jiangnan Cui
      * @Date 2022/8/13 20:18
      * @Version 1.0
      */
     public class IUserDaoTest2 {
         /**
          * @MethodName findAllTest
          * @Description 测试查询所有
          * @Author Jiangnan Cui
          * @Date 20:59 2022/8/13
          */
         @Test
         public void findAllTest() throws IOException {
             SqlSession sqlSession = MybatisUtil.getSession();
             IUserDao userDao = sqlSession.getMapper(IUserDao.class);
             List<User> userList = userDao.findAll();
             for (User user : userList) {
                 System.out.println("user = " + user);
             }
             sqlSession.close();//释放资源
         }
     
         /**
          * @MethodName findByIdTest
          * @Description 根据id查询
          * @Author Jiangnan Cui
          * @Date 20:59 2022/8/13
          */
         @Test
         public void findByIdTest() throws IOException {
             SqlSession sqlSession = MybatisUtil.getSession();
             IUserDao userDao = sqlSession.getMapper(IUserDao.class);
             User user = userDao.findById(1);
             System.out.println("user = " + user);
             sqlSession.close();//释放资源
         }
     
         /**
          * @MethodName findByIdAndNameTest
          * @Description 根据id和name查询
          * @Author Jiangnan Cui
          * @Date 20:59 2022/8/13
          */
         @Test
         public void findByIdAndNameTest() throws IOException {
             SqlSession sqlSession = MybatisUtil.getSession();
             IUserDao userDao = sqlSession.getMapper(IUserDao.class);
             User user = userDao.findByIdAndName(2, "小二王");
             System.out.println("user = " + user);
             sqlSession.close();//释放资源
         }
     
         /**
          * @MethodName addTest
          * @Description 新增用户
          * @Author Jiangnan Cui
          * @Date 21:00 2022/8/13
          */
         @Test
         public void addTest() throws IOException {
             SqlSession sqlSession = null;
             try {
                 sqlSession = MybatisUtil.getSession();
                 IUserDao userDao = sqlSession.getMapper(IUserDao.class);
                 Integer n = userDao.add(new User(10, "熊大", new Date(), '男', "哈尔滨"));
                 System.out.println("受影响的行数 = " + n);
                 mybatis执行增删改时默认事务提交方式是手动的（setAutoCommit(false)），此处需要进行提交
                 sqlSession.commit();//新增需要提交事务
             } catch (Exception e) {
                 e.printStackTrace();
                 sqlSession.rollback();;
             }
         }
     
         /**
          * @MethodName deleteByIdTest
          * @Description 根据id删除
          * @Author Jiangnan Cui
          * @Date 21:11 2022/8/13
          */
         @Test
         public void deleteByIdTest() {
             SqlSession sqlSession = null;
             try {
                 sqlSession = MybatisUtil.getSession();
                 IUserDao userDao = sqlSession.getMapper(IUserDao.class);
                 Integer n = userDao.deleteById(10);
                 System.out.println("受影响的行数 = " + n);
                 //mybatis执行增删改时默认事务提交方式是手动的（setAutoCommit(false)），此处需要进行提交
                 sqlSession.commit();//新增需要提交事务
             } catch (Exception e) {
                 e.printStackTrace();
                 sqlSession.rollback();
             }
         }
     
         /**
          * @MethodName updateByIdTest
          * @Description 根据id修改
          * @Author Jiangnan Cui
          * @Date 21:11 2022/8/13
          */
         @Test
         public void updateTest() {
             SqlSession sqlSession = null;
             try {
                 sqlSession = MybatisUtil.getSession();
                 IUserDao userDao = sqlSession.getMapper(IUserDao.class);
                 Integer n = userDao.update(new User(10, "美羊羊", new Date(), '女', "羊村"));
                 System.out.println("受影响的行数 = " + n);
                 //mybatis执行增删改时默认事务提交方式是手动的（setAutoCommit(false)），此处需要进行提交
                 sqlSession.commit();//新增需要提交事务
             } catch (Exception e) {
                 e.printStackTrace();
                 sqlSession.rollback();
             }
         }
     }

#### 5.11 优化后项目结构 ####

![42e566e12d124009b19839552bace7f8.png][]

[Mybatis _bilibili]: https://www.bilibili.com/video/BV1EE411W7Q1?p=1
[-Mybatis_unique_perfect_-CSDN]: https://blog.csdn.net/unique_perfect/article/details/105587367
[mybatis _ MyBatis 3 _ Introduction]: https://mybatis.org/mybatis-3/
[MyBatis]: https://mybatis.net.cn/
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16]: https://img-blog.csdnimg.cn/191680e8f47f4569b824ef371cc9633c.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAQ29kZXJfQ3Vp,size_20,color_FFFFFF,t_70,g_se,x_16
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBAQ29kZXJfQ3Vp_size_20_color_FFFFFF_t_70_g_se_x_16 1]: https://img-blog.csdnimg.cn/03b319defcd841ccbbf4ede0d5643a31.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBAQ29kZXJfQ3Vp,size_20,color_FFFFFF,t_70,g_se,x_16
[Mybatis _bilibili 1]: https://www.bilibili.com/video/BV1EE411W7Q1?p=2
[IDEA Maven_mybatis_ - wangf98 -]: https://www.cnblogs.com/wvae/p/9607684.html
[Idea2019_Mybatis_demo_-CSDN_idea_mybatis]: https://blog.csdn.net/qq_41741884/article/details/100927567
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[a11c13dbef7a450ca704971ba6e6df8a.png]: https://img-blog.csdnimg.cn/a11c13dbef7a450ca704971ba6e6df8a.png
[243524ce3afa4d32a4a06114531228cb.png]: https://img-blog.csdnimg.cn/243524ce3afa4d32a4a06114531228cb.png
[MyBatis_02-Mybatis_Coder_Cui_-CSDN]: https://blog.csdn.net/xiaocui1995/article/details/124017159
[42e566e12d124009b19839552bace7f8.png]: https://img-blog.csdnimg.cn/42e566e12d124009b19839552bace7f8.png