mybatis入门（实现增删改查）

悠悠 2021-09-19 04:20 659阅读 0赞

目录

1.查询数据库中id=1的记录

2.通过用户名模糊查询记录

3.插入数据

4.根据id修改用户名

5.根据id删除记录

6.使用mybatis开发dao层（查询id为1的记录。对比上面的）

新建javaProject

导入数据库驱动包：

20190430100003118.png

导入mybatis包和它的依赖包：

watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 1

配置约束：https://blog.csdn.net/qq_40323256/article/details/89705297

项目文件如下：

20190430121915938.png 数据库：watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 2

20190430125512784.png

全局配置(SqlMapConfig.xml)

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3. PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-config.dtd">
  6. <configuration>
  7.     <!-- mybatis的环境配置,此信息在开发中只需照搬即可 -->
  8. <!--     在集成spring中是不用这种方式的 -->
  9.     <environments default="development">
  10.         <environment id="development">
  11.             <!-- 配置JDBC事务,此事务由mybatis管理 -->
  12.             <transactionManager type="JDBC"></transactionManager>
  13.             <!-- 配置连接池,此连接池为mybatis连接池 -->
  14.             <dataSource type="POOLED">
  15.                 <property name="driver" value="com.mysql.jdbc.Driver"/>
  16.                 <property name="url" value="jdbc:mysql://localhost:3306/web01"/>
  17.                 <property name="username" value="root"/>
  18.                 <property name="password" value="root"/>
  19.             </dataSource>
  20.         </environment>
  21.     </environments>
  23.     <mappers>
  24.         <mapper resource="mapper/UserMapper.xml"/>
  26. <!-- 下面这种方式推荐 -->
  27.     <!--     <package name="mapper"/>-->
  28.     </mappers>
  30. </configuration>

注意：SqlMapConfig.xml中还可以使用读取配置文件（db.properties）的方式连接数据库，如下：

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3. PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4. "http://mybatis.org/dtd/mybatis-3-config.dtd">
  6. <configuration>
  7. <!-- 读取配置文件 -->
  8.     <properties resource="db.properties"></properties>
  10.     <!-- mybatis的环境配置,此信息在开发中只需照搬即可 -->
  11. <!--     在集成spring中是不用这种方式的 -->
  12.     <environments default="development">
  13.         <environment id="development">
  14.             <!-- 配置JDBC事务,此事务由mybatis管理 -->
  15.             <transactionManager type="JDBC"></transactionManager>
  16.             <!-- 配置连接池,此连接池为mybatis连接池 -->
  17.             <dataSource type="POOLED">
  18.                 <property name="driver" value="${jdbc.driver}"/>
  19.                 <property name="url" value="${jdbc.url}"/>
  20.                 <property name="username" value="${jdbc.username}"/>
  21.                 <property name="password" value="${jdbc.password}"/>
  22.             </dataSource>
  23.         </environment>
  24.     </environments>
  26.     <mappers>
  27.         <mapper resource="mapper/UserMapper.xml"/>
  28. <!-- 下面这种方式推荐 -->
  29.     <!--     <package name="mapper"/>-->
  30.     </mappers>
  32. </configuration>

db.properties:

  1. jdbc.driver=com.mysql.jdbc.Driver
  2. jdbc.url=jdbc:mysql://localhost:3306/web01
  3. jdbc.username=root
  4. jdbc.password=root

1.查询数据库中id=1的记录

UserMapper.xml:

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper    
  3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"    
  4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  6. <mapper namespace="UserMapper">
  8.     <select id="selectUserById" parameterType="Integer" resultType="com.sikiedu.bean.User">
  9.         SELECT * FROM user WHERE id =#{id}
  10.     </select>
  11. </mapper>

User.java:

  1. package com.sikiedu.bean;
  3. public class User {
  4.     private Integer id;
  5.     private String username;
  6.     private String password;
  8.     public Integer getId() {
  9.         return id;
  10.     }
  11.     public void setId(Integer id) {
  12.         this.id = id;
  13.     }
  14.     public String getUsername() {
  15.         return username;
  16.     }
  17.     public void setUsername(String username) {
  18.         this.username = username;
  19.     }
  20.     public String getPassword() {
  21.         return password;
  22.     }
  23.     public void setPassword(String password) {
  24.         this.password = password;
  25.     }
  27.     @Override
  28.     public String toString() {
  29.         return "User [id=" + id + ", username=" + username + ", password=" + password + "]";
  30.     }
  33. }

HelloMyBatis.java:

  1. package test;
  3. import java.io.IOException;
  4. import java.io.InputStream;
  6. import org.apache.ibatis.io.Resources;
  7. import org.apache.ibatis.session.SqlSession;
  8. import org.apache.ibatis.session.SqlSessionFactory;
  9. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  10. import org.junit.Test;
  12. import com.sikiedu.bean.User;
  14. public class HelloMyBatis {
  16.     @Test
  17.     public void Test() throws IOException{
  18.         String resource="sqlMapConfig.xml";
  19.         InputStream in = Resources.getResourceAsStream(resource);
  20.         SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  21.         SqlSessionFactory ssf=ssfb.build(in);
  22.         SqlSession session  = ssf.openSession();
  24.         User user = session.selectOne("UserMapper.selectUserById",1);
  25.         System.out.println(user);
  26.     }
  27. }

运行结果：

20190430122407482.png

2.通过用户名模糊查询记录

HelloBatis.java:

  1. @Test
  2.     public void Test2() throws IOException{
  3.         String resource="sqlMapConfig.xml";
  4.         InputStream in = Resources.getResourceAsStream(resource);
  5.         SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  6.         SqlSessionFactory ssf=ssfb.build(in);
  7.         SqlSession session  = ssf.openSession();
  9.         List<User> list = session.selectList("UserMapper.selectUserByName", "李");
  10.         for (User u : list) {
  11.             System.out.println(u);
  12.         }
  13.     }

UserMapper.xml:

  1. <!--     ${}字符串拼接  这里不推荐 -->
  2. <!--     #{}占位符 推荐 -->
  3.     <select id="selectUserByName" parameterType="String" resultType="com.sikiedu.bean.User">
  4. <!--         SELECT * FROM user WHERE username like '%${value}%' -->
  5.             SELECT * FROM user WHERE username like "%"#{name}"%"
  6.     </select>

运行结果：

20190430123730137.png

3.插入数据

HelloMyBatis.java:

  1. @Test
  2.     public void Test3() throws IOException{
  3.         String resource="sqlMapConfig.xml";
  4.         InputStream in = Resources.getResourceAsStream(resource);
  5.         SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  6.         SqlSessionFactory ssf=ssfb.build(in);
  7.         SqlSession session  = ssf.openSession();
  9.         User user=new User();
  10.         user.setUsername("小明");
  11.         user.setPassword("1");
  13.         session.insert("UserMapper.insertUser",user);
  14.         session.commit();
  15.     }

UserMapper.xml:

  1. <insert id="insertUser" parameterType="com.sikiedu.bean.User">
  2.         insert into user values(null,#{username},#{password})
  3.     </insert>

运行结果：

watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 3

4.根据id修改用户名

HelloMyBatis.java:

  1. @Test
  2.     public void Test4() throws IOException{
  3.         String resource="sqlMapConfig.xml";
  4.         InputStream in = Resources.getResourceAsStream(resource);
  5.         SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  6.         SqlSessionFactory ssf=ssfb.build(in);
  7.         SqlSession session  = ssf.openSession();
  9.         User user=new User();
  10.         user.setId(14);
  11.         user.setUsername("小疆");
  13.         session.insert("UserMapper.updateUser",user);
  14.         session.commit();
  15.     }

UserMapper.xml:

  1. <update id="updateUser" parameterType="com.sikiedu.bean.User">
  2.         update user set username=#{username} where id=#{id}
  3.     </update>

运行结果：

watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 4

5.根据id删除记录

HelloMyBatis.java:

  1. @Test
  2.     public void Test5() throws IOException{
  3.         String resource="sqlMapConfig.xml";
  4.         InputStream in = Resources.getResourceAsStream(resource);
  5.         SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  6.         SqlSessionFactory ssf=ssfb.build(in);
  7.         SqlSession session  = ssf.openSession();
  9.         session.delete("UserMapper.deleteUser",14);
  10.         session.commit();
  11.     }

UserMapper.xml:

  1. <delete id="deleteUser" parameterType="Integer">
  2.         delete from user where id=#{id}
  3.     </delete>

运行结果：id=14的记录被删除了

watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 5

6.使用mybatis开发dao层（查询id为1的记录。对比上面的）

20190430201201666.png

UserDao.java:

  1. package com.sikiedu.dao;
  3. import com.sikiedu.bean.User;
  5. public interface UserDao {
  7.         User getUserById(Integer id);
  9. }

UserDaolmpl.java:

  1. package com.sikiedu.dao;
  3. import org.apache.ibatis.session.SqlSession;
  4. import org.apache.ibatis.session.SqlSessionFactory;
  6. import com.sikiedu.bean.User;
  8. public class UserDaolmpl implements UserDao {
  9.     SqlSessionFactory ssf;
  12.     public UserDaolmpl(SqlSessionFactory ssf) {
  13.         super();
  14.         this.ssf = ssf;
  15.     }
  18.     @Override
  19.     public User getUserById(Integer id) {
  20.         SqlSession session  = ssf.openSession();
  21.         return session.selectOne("UserMapper.selectUserById",id);
  22.     }
  24. }

UserDaoTest.java:

  1. package test;
  3. import java.io.IOException;
  4. import java.io.InputStream;
  6. import org.apache.ibatis.io.Resources;
  7. import org.apache.ibatis.session.SqlSessionFactory;
  8. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  9. import org.junit.Test;
  11. import com.sikiedu.bean.User;
  12. import com.sikiedu.dao.UserDao;
  13. import com.sikiedu.dao.UserDaolmpl;
  15. public class UserDaoTest {
  17.     private static SqlSessionFactory ssf;
  19.     static{
  20.         String resource="sqlMapConfig.xml";
  21.         InputStream in;
  22.         try {
  23.             in = Resources.getResourceAsStream(resource);
  24.             SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  25.             ssf=ssfb.build(in);
  26.             in.close();
  28.         } catch (IOException e) {
  29.             e.printStackTrace();
  30.         }
  31.     }
  32.     @Test
  33.     public void DaoTest(){
  34.         UserDao dao=new UserDaolmpl(ssf);
  35.         User user=dao.getUserById(1);
  36.         System.out.println(user);
  37.     }
  38. }

运行结果：

20190430201319553.png

7.包装类

UserVo.java:

  1. package com.sikiedu.bean;
  3. public class UserVo {
  4.     private User user;
  6.     public User getUser() {
  7.         return user;
  8.     }
  10.     public void setUser(User user) {
  11.         this.user = user;
  12.     }
  14. }

UserMapper.java:

  1. public User selectUserByUserVo(UserVo vo);

UserMapper.xml: 

  1. <select id="selectUserByUserVo" parameterType="com.sikiedu.bean.UserVo" resultType="com.sikiedu.bean.User">
  2.         SELECT * FROM user WHERE id =#{user.id}
  3.     </select>

MapperTest.java:

  1. @Test
  2.     public void Test3() throws IOException{
  3.         String resource="sqlMapConfig.xml";
  4.         InputStream in = Resources.getResourceAsStream(resource);
  5.         SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
  6.         SqlSessionFactory ssf=ssfb.build(in);
  7.         SqlSession session  = ssf.openSession();
  9.         UserMapper mapper = session.getMapper(UserMapper.class);
  10.         UserVo vo=new UserVo();
  11.         User u=new User();
  12.         u.setId(1);
  13.         vo.setUser(u);
  15.         User user = mapper.selectUserByUserVo(vo);
  16.         System.out.println(user);
  17.     }

运行结果：

20190501121711213.png

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