• MyBatis之增删查改功能

    文章目录

    • 一、创建各种类
    • 二、MyBatis的各种功能
      • 1、查询

        查询User表所有用户的信息

        因为查询的内容返回的数据不止一条，因此我们用List集合作为返回值

        SelectMapeer接口下定义方法名：List getAllUser()

        1. public interface SelectMapper {
        2.     /*
        3.         若查询多条，不能用实体类对象为返回值，否则报错
        4.     */
        5.  
        6.     //查询所有信息
        7.     List getAllUser();
        8.  
        9. }

        SelectMapper的xml文件下写sql语句

        1. "1.0" encoding="UTF-8" ?>
        3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
        5. "com.mybatis.mapper.SelectMapper">
        6.  
        8.     
        9.

        注意：mapper的namespace必须对应接口名，select的id必须是我们写的方法名，两个必须要一样。查询结果需要返回，因此有resultType为实体类名 

        SelectMapperText类开始测试

        1. import com.mybatis.Util.SqlSessionUtil;
        2. import com.mybatis.mapper.SelectMapper;
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.io.Resources;
        5. import org.apache.ibatis.session.SqlSession;
        6. import org.apache.ibatis.session.SqlSessionFactory;
        7. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
        8. import org.junit.Test;
        9.  
        10. import javax.crypto.spec.PSource;
        11. import java.io.IOException;
        12. import java.io.InputStream;
        13. import java.util.List;
        14. import java.util.Map;
        15.  
        16. public class SelectMapperText {
        17.  
        18.     @Test
        19.     public void getAllUser() throws IOException {
        20.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        21.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        22.         SqlSession sqlSession = sessionFactory.openSession(true);
        23.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        24.         List allUser = mapper.getAllUser();
        25.         allUser.forEach(s-> System.out.println(s));
        26.     }
        27.  
        28. }

         运行getAllUser后为：

        成功查到所有用户信息！！！ 

        2、增加功能 

        向User表增加一个用户，用户信息为：

        用户名：sb,密码：123456，年龄：20，性别：男，邮件：123456@qq.com

         SelectMapeer接口下定义方法名：void insertUser(User user);

        1. package com.mybatis.mapper;
        2.  
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.annotations.Param;
        5.  
        6. import java.util.List;
        7. import java.util.Map;
        8.  
        9. public interface SelectMapper {
        10.  
        11.     //查询所有信息
        12.     List getAllUser();
        13.  
        14.     //插入用户信息
        15.     void insertUser(User user);
        16. }

        SelectMapper的xml文件下写sql语句

        1. "1.0" encoding="UTF-8" ?>
        3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
        5. "com.mybatis.mapper.SelectMapper">
        6.  
        8.     
        9.  
        11.     "insertUser">
        12.         insert into user values (null,#{username},#{password},#{age},#{sex},#{email})
        13.     
        14.

        SelectMapperText类开始测试

        1. import com.mybatis.Util.SqlSessionUtil;
        2. import com.mybatis.mapper.SelectMapper;
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.io.Resources;
        5. import org.apache.ibatis.session.SqlSession;
        6. import org.apache.ibatis.session.SqlSessionFactory;
        7. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
        8. import org.junit.Test;
        9.  
        10. import javax.crypto.spec.PSource;
        11. import java.io.IOException;
        12. import java.io.InputStream;
        13. import java.util.List;
        14. import java.util.Map;
        15.  
        16. public class SelectMapperText {
        17.  
        18.     @Test
        19.     public void getAllUser() throws IOException {
        20.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        21.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        22.         SqlSession sqlSession = sessionFactory.openSession(true);
        23.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        24.         List allUser = mapper.getAllUser();
        25.         allUser.forEach(s-> System.out.println(s));
        26.     }
        27.  
        28.     @Test
        29.     public void insertUser() throws IOException {
        30.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        31.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        32.         SqlSession sqlSession = sessionFactory.openSession(true);
        33.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        34.         User user = new User(null,"sb","123456",20,"男","123456@qq.com");
        35.         mapper.insertUser(user);
        36.     }
        37.  
        38. }

        成功添加用户信息！！！  

        3、修改功能 

        修改用户名为admin的信息，将性别改为女

        SelectMapeer接口下定义方法名： void updateUser(String username)

        1. package com.mybatis.mapper;
        2.  
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.annotations.Param;
        5.  
        6. import java.util.List;
        7. import java.util.Map;
        8.  
        9. public interface SelectMapper {
        10.  
        11.     //查询所有信息
        12.     List getAllUser();
        13.  
        14.     //插入用户信息
        15.     void insertUser(User user);
        16.  
        17.     //修改用户信息
        18.     void updateUser(@Param("username") String username);//用注释当sql名
        19. }

        SelectMapper的xml文件下写sql语句

        1. "1.0" encoding="UTF-8" ?>
        3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
        5. "com.mybatis.mapper.SelectMapper">
        6.  
        8.     
        9.  
        11.     "insertUser">
        12.         insert into user values (null,#{username},#{password},#{age},#{sex},#{email})
        13.     
        14.  
        16.     "updateUser">
        17.         update user set sex = '女' where username=#{username}
        18.     
        19.

        SelectMapperText类开始测试

        1. import com.mybatis.Util.SqlSessionUtil;
        2. import com.mybatis.mapper.SelectMapper;
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.io.Resources;
        5. import org.apache.ibatis.session.SqlSession;
        6. import org.apache.ibatis.session.SqlSessionFactory;
        7. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
        8. import org.junit.Test;
        9.  
        10. import javax.crypto.spec.PSource;
        11. import java.io.IOException;
        12. import java.io.InputStream;
        13. import java.util.List;
        14. import java.util.Map;
        15.  
        16. public class SelectMapperText {
        17.  
        18.     @Test
        19.     public void getAllUser() throws IOException {
        20.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        21.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        22.         SqlSession sqlSession = sessionFactory.openSession(true);
        23.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        24.         List allUser = mapper.getAllUser();
        25.         allUser.forEach(s-> System.out.println(s));
        26.     }
        27.  
        28.     @Test
        29.     public void insertUser() throws IOException {
        30.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        31.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        32.         SqlSession sqlSession = sessionFactory.openSession(true);
        33.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        34.         User user = new User(null,"sb","123456",20,"男","123456@qq.com");
        35.         mapper.insertUser(user);
        36.     }
        37.  
        38.    @Test
        39.     public void updateUser() throws IOException {
        40.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        41.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        42.         SqlSession sqlSession = sessionFactory.openSession(true);
        43.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        44.         mapper.updateUser("admin");
        45.     }
        46.  
        47. }

        成功修改用户信息！！！ 

        4、删除功能 

        删除用户为“root”的所有信息

        SelectMapeer接口下定义方法名：void deleteUser(String username)

        1. package com.mybatis.mapper;
        2.  
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.annotations.Param;
        5.  
        6. import java.util.List;
        7. import java.util.Map;
        8.  
        9. public interface SelectMapper {
        10.  
        11.     //查询所有信息
        12.     List getAllUser();
        13.  
        14.     //插入用户信息
        15.     void insertUser(User user);
        16.  
        17.     //修改用户信息
        18.     void updateUser(@Param("username") String username);//用注释当sql名
        19.  
        20.     //删除用户信息
        21.     void deleteUser(@Param("username") String username);
        22. }

        SelectMapper的xml文件下写sql语句

        1. "1.0" encoding="UTF-8" ?>
        3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
        5. "com.mybatis.mapper.SelectMapper">
        6.  
        8.     
        9.  
        11.     "insertUser">
        12.         insert into user values (null,#{username},#{password},#{age},#{sex},#{email})
        13.     
        14.  
        16.     "updateUser">
        17.         update user set sex = '女' where username=#{username}
        18.     
        19.  
        21.     "deleteUser">
        22.         delete  from user where username = #{username}
        23.

        SelectMapperText类开始测试 

        1. import com.mybatis.Util.SqlSessionUtil;
        2. import com.mybatis.mapper.SelectMapper;
        3. import com.mybatis.pojo.User;
        4. import org.apache.ibatis.io.Resources;
        5. import org.apache.ibatis.session.SqlSession;
        6. import org.apache.ibatis.session.SqlSessionFactory;
        7. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
        8. import org.junit.Test;
        9.  
        10. import javax.crypto.spec.PSource;
        11. import java.io.IOException;
        12. import java.io.InputStream;
        13. import java.util.List;
        14. import java.util.Map;
        15.  
        16. public class SelectMapperText {
        17.  
        18.     @Test
        19.     public void getAllUser() throws IOException {
        20.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        21.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        22.         SqlSession sqlSession = sessionFactory.openSession(true);
        23.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        24.         List allUser = mapper.getAllUser();
        25.         allUser.forEach(s-> System.out.println(s));
        26.     }
        27.  
        28.     @Test
        29.     public void insertUser() throws IOException {
        30.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        31.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        32.         SqlSession sqlSession = sessionFactory.openSession(true);
        33.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        34.         User user = new User(null,"sb","123456",20,"男","123456@qq.com");
        35.         mapper.insertUser(user);
        36.     }
        37.  
        38.    @Test
        39.     public void updateUser() throws IOException {
        40.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        41.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        42.         SqlSession sqlSession = sessionFactory.openSession(true);
        43.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        44.         mapper.updateUser("admin");
        45.     }
        46.  
        47.     @Test
        48.     public void deleteUser() throws IOException {
        49.         InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        50.         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        51.         SqlSession sqlSession = sessionFactory.openSession(true);
        52.         SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
        53.         mapper.deleteUser("root");
        54.     }
        55. }

         成功删除用户信息！！！

        三、总结

                首先创造好接口写入要进行的方法名，然后创建xml文件专门写sql语句，值得注意的是：namespace要和接口名相同，id名要和接口里面的方法名相同，在测试类中：先获取映射文件，然后创建数据会议工厂生成数据会议，最后创建mapper使用接口的函数。

        总之流程为：

                1、创建接口写方法名。

                2、创建xml文件写sql语句。

                3、测试类进行测试

                如果本篇文章对你有用的话，请一键三连支持一下博主，一起共同学习共同进步！！！

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  • 原文地址：https://blog.csdn.net/m0_62476845/article/details/132998876