MyBatis

MyBatis

概念

• MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作。
• MyBatis 可以通过简单的 XML 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录。
• 官网：https://mybatis.org/mybatis-3/zh/index.html

持久层

• 负责将数据保存到数据库的那一层代码
• JavaEE三层架构：表现层、业务层、持久层

框架

• 框架就是一个半成品软件，是一套可重用的、通用的、软件基础代码结构
• 在框架的基础之上构建软件编写更加高效、规范、通用、可扩展

MyBatis快速入门

查询user表中的所有数据

1. 创建user表，添加数据

2. 创建模块，导入坐标

   
   
       4.0.0
   
       com.zxx
       MyBatis_Study
       1.0-SNAPSHOT
   
       
           8
           8
       
   
       
           
           
               mysql
               mysql-connector-java
               5.1.32
           
   
           
           
               org.mybatis
               mybatis
               3.5.5
           
   
           
           
               junit
               junit
               4.13
               test
           
   
           
           
               org.slf4j
               slf4j-api
               1.7.36
               test
           
   
           
           
               ch.qos.logback
               logback-classic
               1.2.3
           
   
           
           
               ch.qos.logback
               logback-core
               1.2.3
           
       
   
   
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3. 编写MyBatis核心配置文件 --> 替换连接信息，解决硬编码问题

   
   
   
   
       
       
           
       
       
       
       
           
               
               
                   
                   
                   
                   
                   
               
           
   
           
               
               
                   
                   
                   
                   
                   
               
           
       
   
       
           
           
   
           
           
       
   
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4. 编写SQL映射文件 --> 统一管理SQL语句，解决硬编码问题

   
   
   
   
       
           select * from user;
       
   
   
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5. 编码

   1. 定义POJO类

      package com.zxx.pojo;
      
      public class User {
          private String name;
          private String password;
      
          public String getName() {
              return name;
          }
      
          public void setName(String name) {
              this.name = name;
          }
      
          public String getPassword() {
              return password;
          }
      
          public void setPassword(String password) {
              this.password = password;
          }
      
          @Override
          public String toString() {
              return "User{" +
                      "name='" + name + '\'' +
                      ", password='" + password + '\'' +
                      '}';
          }
      }
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   2. 加载核心配置文件，获取SqlSessionFactory对象

   3. 获取SqlSession对象，执行SQL语句

   4. 释放资源

      package com.zxx;
      
      import com.zxx.pojo.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;
      
      /*
       * MyBatis快速入门
       */
      public class MyBatis {
          public static void main(String[] args) throws Exception {
              //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
              String resource = "mybatis-config.xml";
              InputStream inputStream = Resources.getResourceAsStream(resource);
              SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
      
              //2.获取SqlSession对象，用它来执行SQL
              SqlSession sqlSession = sqlSessionFactory.openSession();
      
              //3. 执行SQL
              List users = sqlSession.selectList("test.selectAllUser");
      
              System.out.println(users);
      
              //4.释放资源
              sqlSession.close();
          }
      }
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Mapper代理开发

1. 定义与SQL映射文件同名的Mapper接口，并且将Mapper接口和SQL的映射文件放到同一个路径下，可以在Resources路径下创建与接口路径相同的结构，需要用 / 分隔，编译后会在同一个目录下

2. 设置SQL映射文件的namespace属性为Mapper接口全限定名

3. 在Mapper接口中定义方法，方法名就是SQL映射文件中的sql语句的id,并保持参数类型和返回值类型一致

   package com.zxx.mapper;
   
   import com.zxx.pojo.User;
   
   import java.util.List;
   
   public interface UserMapper {
       List selectAllUser();
   }
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4. 编码

   package com.zxx;
   
   import com.zxx.mapper.UserMapper;
   import com.zxx.pojo.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;
   
   /*
    * MyBatis代理开发
    */
   public class MyBatis2 {
       public static void main(String[] args) throws Exception {
           //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
           String resource = "mybatis-config.xml";
           InputStream inputStream = Resources.getResourceAsStream(resource);
           SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
   
           //2.获取SqlSession对象，用它来执行SQL
           SqlSession sqlSession = sqlSessionFactory.openSession();
   
           //3. 执行SQL
           // 3.1 获取UserMapper接口的代理对象
           UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
           List users = userMapper.selectAllUser();
   
           System.out.println(users);
   
           //4.释放资源
           sqlSession.close();
       }
   }
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配置文件完成增删改查

安装MyBatisX插件

1. 查询
   • 查询所有数据
     • 编写接口方法
     • 编写SQL语句
     • 执行方法
   • 查看详情
   • 条件查询
2. 添加
3. 修改
   • 修改全部字段
   • 修改动态字段
4. 删除
   • 删除一个
   • 批量删除

实体类

package com.zxx.pojo;

public class Brand {
    private Integer id;
    private String brandName;
    private String companyName;
    private Integer ordered;
    private String description;
    private Integer status;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getBrandName() {
        return brandName;
    }

    public void setBrandName(String brandName) {
        this.brandName = brandName;
    }

    public String getCompanyName() {
        return companyName;
    }

    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    }

    public Integer getOrdered() {
        return ordered;
    }

    public void setOrdered(Integer ordered) {
        this.ordered = ordered;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    @Override
    public String toString() {
        return "Brand{" +
                "id=" + id +
                ", brandName='" + brandName + '\'' +
                ", companyName='" + companyName + '\'' +
                ", ordered=" + ordered +
                ", description='" + description + '\'' +
                ", status=" + status +
                '}';
    }
}

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Mapper.xml

    

    
    
        id, brand_name as brandName, company_name as companyName,ordered, description, status
    



    
    
        
        
        
    


    

    
    
        select *
        from tb_brand;
    

    
    
        select *
        from tb_brand
        where id = ${id};
    


    
        select *
        from tb_brand
        where status = #{status}
        and company_name like #{companyName}
        and brand_name like #{brandName}
    

    
        select *
        from tb_brand
        where status = #{status}
        and company_name like #{companyName}
        and brand_name like #{brandName}
    

    
    
    
    
    
    
    

    
    
        select *
        from tb_brand
        
        
            
                and status = #{status}
            
            
                and company_name like #{companyName}
            
            
                and brand_name like #{brandName}
            
        
    

    
        select * from tb_brand
        where
        
            
                status = #{status}
            
            
                company_name like #{companyName}
            
            
                brand_name like #{brandName}
            
            
                1=1
            
        
    

    
    
        INSERT INTO tb_brand ( brand_name, company_name, ordered, description, status )
        VALUES
        ( #{brandName},#{companyName},#{ordered},#{description},#{status}
        )
    

    
        update tb_brand
            set brand_name = #{brandName},
                company_name = #{companyName},
                ordered = #{ordered},
                description = #{description},
                status = #{status}
        where id = #{id}
    

    
        update tb_brand
            
                
                    brand_name = #{brandName},
                
                
                    company_name = #{companyName},
                
                
                    ordered = #{ordered},
                
                
                    description = #{description},
                
                
                    status = #{status}
                
            
        where id = #{id}
    

    
    
        delete from tb_brand where id = #{id}
    

    
    
        delete from tb_brand where id
        in(
            
            
                #{id}
            
         )

    


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Mapper接口

package com.zxx.mapper;

import com.zxx.pojo.Brand;
import org.apache.ibatis.annotations.Param;

import java.util.List;
import java.util.Map;

public interface BrandMapper {
    /*
    * 查询所有
    */
    List selectAll();

    /*
    * 查看详情
    */
    Brand selectById(Integer id);

    /*
    * 多条件动态查询: 散装参数
    */
    List selectByCondition1(@Param("status") int status,@Param("companyName") String companyName,@Param("brandName") String brandName);

    /*
     * 多条件动态查询： 对象参数,对象属性的名称要和参数占位符名称一致
     */
    List selectByCondition2(Brand brand);

    /*
     * 多条件动态查询：map参数
     */
    List selectByCondition3(Map map);

    /*
    * 单条件动态查询
    * */
    List selectByConditionSingle(Brand brand);

    /*
    *  添加一个对象
    * */
    void add(Brand brand);

    /*
    * 修改全部字段
    * */
    int update(Brand brand);

    /*
     * 动态修改字段
     * */
    int updateByCondition(Brand brand);

    /*
    * 根据Id删除
    * */
    void deleteById(Integer id);

    /*
    * 批量删除
    * */
    void deleteByIds(@Param("ids") int[] ids);
}

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测试类

package com.zxx.mapper;

import com.zxx.pojo.Brand;
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.HashMap;
import java.util.List;
import java.util.Map;

public class MyBatis_Test {

    @Test
    public void testSelectAll() throws IOException {
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        List brands = brandMapper.selectAll();
        System.out.println(brands);

        //释放资源
        sqlSession.close();
    }

    @Test
    public void testSelectById() throws IOException {
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        Brand brands = brandMapper.selectById(2);
        System.out.println(brands);

        //释放资源
        sqlSession.close();
    }

    @Test
    public void testSelectByCondition1() throws IOException {
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        List brands = brandMapper.selectByCondition1(1, "%华为%", "%华为%");
        System.out.println(brands);

        //释放资源
        sqlSession.close();
    }

    @Test
    public void testSelectByCondition2() throws IOException {

        Brand brand = new Brand();
        brand.setStatus(1);
        brand.setCompanyName("%华为%");
        brand.setBrandName("%华为%");

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        List brands = brandMapper.selectByCondition2(brand);
        System.out.println(brands);

        //释放资源
        sqlSession.close();
    }

    @Test
    public void testSelectByCondition3() throws IOException {
        Map map = new HashMap<>();
        map.put("status", 1);
        //map.put("companyName","%华为%");
        // map.put("brandName","%华为%");
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        List brands = brandMapper.selectByCondition3(map);
        System.out.println(brands);

        //释放资源
        sqlSession.close();
    }

    @Test
    public void testSelectByConditionSingle() throws IOException {
        Brand brand = new Brand();
        //brand.setStatus(1);
        //brand.setCompanyName("%华为%");
        brand.setBrandName("%华为%");

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        List brands = brandMapper.selectByConditionSingle(brand);
        System.out.println(brands);

        //释放资源
        sqlSession.close();
    }

    @Test
    public void testAdd() throws IOException {
        Brand brand = new Brand();
        brand.setStatus(1);
        brand.setCompanyName("波导手机");
        brand.setBrandName("波导");
        brand.setDescription("手机中的战斗机");
        brand.setOrdered(100);

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        brandMapper.add(brand);

        /*//5.手动提交事务
        sqlSession.commit();*/

        List brands = brandMapper.selectAll();
        System.out.println(brands);
        //释放资源
        sqlSession.close();
    }

    @Test
    public void testAdd2() throws IOException {
        Brand brand = new Brand();
        brand.setStatus(1);
        brand.setCompanyName("波导手机");
        brand.setBrandName("波导");
        brand.setDescription("手机中的战斗机");
        brand.setOrdered(100);

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        brandMapper.add(brand);
        Integer id = brand.getId();
        System.out.println(id);

        /*//5.手动提交事务
        sqlSession.commit();*/

        List brands = brandMapper.selectAll();
        System.out.println(brands);
        //释放资源
        sqlSession.close();
    }

    @Test
    public void testUpdate() throws IOException {
        Brand brand = new Brand();
        brand.setStatus(1);
        brand.setCompanyName("波导手机");
        brand.setBrandName("波导");
        brand.setDescription("波导手机,手机中的战斗机");
        brand.setOrdered(200);
        brand.setId(8);

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        brandMapper.update(brand);
        //释放资源
        sqlSession.close();
    }

    @Test
    public void testupdateByCondition() throws IOException {
        Brand brand = new Brand();
        brand.setStatus(4);
        // brand.setCompanyName("波导手机");
        //brand.setBrandName("波导");
        //brand.setDescription("波导手机,手机中的战斗机");
        //brand.setOrdered(200);
        brand.setId(7);

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        brandMapper.updateByCondition(brand);
        //释放资源
        sqlSession.close();
    }

    @Test
    public void testDeleteById() throws IOException {
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        brandMapper.deleteById(7);

        List brands = brandMapper.selectAll();
        System.out.println(brands);
        //释放资源
        sqlSession.close();
    }

    @Test
    public void testDeleteByIds() throws IOException {
        int[] ids = new int[]{5,6};

        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3.获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4.执行方法
        brandMapper.deleteByIds(ids);

        List brands = brandMapper.selectAll();
        System.out.println(brands);
        //释放资源
        sqlSession.close();
    }
}

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注解完成增删改查

直接在接口上添加注解 并完成SQL

package com.zxx.mapper;

import com.zxx.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface UserMapper {
    List selectAllUser();

    User select(@Param("name") String username, @Param("password") String password);

    @Select("select * from user where id=#{id}")
    User selectUserById(int id);

}
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测试类

package com.zxx.mapper;

import com.zxx.pojo.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;

public class MyBatis_Test2 {

    @Test
    public void testUserSelect() throws IOException {
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        User user = userMapper.select("'zxx'","'zxxpass'");
        System.out.println(user);
    }

    @Test
    public void testUserSelectUserById() throws IOException {
        //1.加载MyBatis的核心配置文件，获取 SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取SqlSession对象，用它来执行SQL
        //SqlSession sqlSession = sqlSessionFactory.openSession();
        //自动提交事务
        SqlSession sqlSession = sqlSessionFactory.openSession(true);

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        User user = userMapper.selectUserById(1);
        System.out.println(user);
    }
}
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