一、导入依赖

在pom.xml导入Mybatis 和Mysql的相关依赖。

代码如下：

 1         
 2         <dependency>
 3             <groupId>org.mybatisgroupId>
 4             <artifactId>mybatisartifactId>
 5             <version>3.5.9version>
 6         dependency>
 7 
 8         
 9         <dependency>
10             <groupId>junitgroupId>
11             <artifactId>junitartifactId>
12             <version>4.13.2version>
13             <scope>testscope>
14         dependency>
15 
16         
17         <dependency>
18             <groupId>mysqlgroupId>
19             <artifactId>mysql-connector-javaartifactId>
20             <version>8.0.28version>
21         dependency>

二、核心配置文件

mybatis-config.xml是Mybatis的核心配置文件。

mybatis-config.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">
 5 <configuration>
 6     
 7     <environments default="development">
 8         <environment id="development">
 9             <transactionManager type="JDBC"/>
10             <dataSource type="POOLED">
11                 <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
12                 <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
13                 <property name="username" value="root"/>
14                 <property name="password" value="529529"/>
15             dataSource>
16         environment>
17     environments>
18     
19     <mappers>
20         <mapper resource="mappers/UserMapper.xml"/>
21     mappers>
22 configuration>

三、映射文件

创建SQL映射的xml文件。

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">
 5 <mapper namespace="com.ang.Mapper.UserMapper">
 6     
 7     <select id="findUserById" parameterType="int" resultType="com.ang.demo1.User">
 8         select *
 9         from t_user
10         where id = #{id}
11     select>
12 mapper>

四、测试类

 1 public class TestMybatis {
 2     private SqlSessionFactory sqlSessionFactory;
 3     private SqlSession sqlSession;
 4 
 5     @Before
 6     public void init() {
 7         //加载核心配置文件
 8         try (InputStream is = Resources.getResourceAsStream("mybatis-config.xml")) {
 9             //获取SqlSessionFactoryBuilder
10             SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
11             //获取SqlSessionFactory
12             sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
13             //获取SqlSession
14             sqlSession = sqlSessionFactory.openSession();
15         } catch (IOException e) {
16             e.printStackTrace();
17         }
18     }
19 
20     @Test
21     public void testUser() {
22         //查找
23         User user2 = sqlSession.selectOne("findUserById",3);
24         System.out.println(user2.toString());
25     }
26 
27     @After
28     public void destroy() {
29         //提交事务
30         sqlSession.commit();
31         //关闭sqlSession
32         sqlSession.close();
33     }
34 }