【Mybatis-Spring】Spring、Mybatis在Maven中的快速整合

1. 起别名
2. 配置数据源

mybatis-config.xml:

```java
public interface UserMapper {
    public List selectUser();
}
```

Mapper.xml :

	
	
	
	
	    
	    
	        select * from studb.student;
	    
	
 
⚠️：必须和Mapper接口同名且在同一路径下；  
 
5. 在Mybatis配置文件中注册Mapper映射文件 

       
       
   
 
6. 测试 
@Test
public void test01() throws IOException {
   
   String resource="mybatis-config.xml";
   InputStream in = Resources.getResourceAsStream(resource);
   
   SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(in);
   SqlSession sqlSession = sessionFactory.openSession(true);
   
   UserMapper mapper = sqlSession.getMapper(UserMapper.class);
   
   List users = mapper.selectUser();
   
   for (User user : users) {
       System.out.println(user);
   }
}
 
7. Mapper映射文件读取异常问题 
Invalid bound statement (not found): com:.luo.mapper.UserMapper.selectUser
检查语法（映射文件与实体类是否对应、Mybatis配置文件中注册映射文件是否正确）
检查输出了Mapper映射文件的class
如果没有输出class文件，则在pom.xml中进行额外配置使用Maven静态资源过滤 ：

    
        
            src/main/java
            
                **
UserMapper mapper = sqlSession.getMapper(UserMapper.class);

List users = mapper.selectUser();

for (User user : users) {
   System.out.println(user);
}
 
而Spring在applicationContext.xml中使用org.mybatis.spring.SqlSessionFactoryBean创建SqlSessionFactory，并在其中绑定mybatis-config.xml核心配置文件，以及注册Mapper.xml，使用org.mybatis.spring.SqlSessionTemplate创建SqlSession：
 
    
    
    
    
    



    

 
创建Mapper的实现类：
 
public class UserMapperImpl implements UserMapper{
    SqlSessionTemplate sqlSession;
    public void setSqlSession(SqlSessionTemplate sqlSession) {
        this.sqlSession = sqlSession;
    }
    @Override
    public List selectUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}
 
并在spring中托管，注入SqlSession：
 

   

 
最后在使用的时候，只需要从SpringIOC容器中获取Mapper实现类对象：
 
@Test
public void test02() throws IOException {
    ApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
    List users = context.getBean("userMapper",UserMapper.class).selectUser();
    
    for (User user : users) {
        System.out.println(user.toString());
    }
}
 
 
整合方式二：
 因为一次使用最好创建一个私有的SqlSession，使用完立刻关闭，在SpringIOC容器托管，可以做到让Spring负责SqlSession的创建，但需要一个SqlSession就要一个，十分不方便；所以还可以在需要使用SqlSession时通过继承SqlSessionDaoSupport，就可以通过getSqlSession()直接获得一个可以使用的SqlSession：
public class UserMapperImpl2 extends SqlSessionDaoSupport implements UserMapper{
    @Override
    public List selectUser() {
        UserMapper mapper = getSqlSession().getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}
 绝对不要忘记要在SpringIOC容器中托管，并注入SqlSessionFactory：

   
       
       
       
   
    
        
    

 使用：
@Test
public void test03() throws IOException {
   ApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
   List users = context.getBean("userMapper2",UserMapper.class).selectUser();

   for (User user : users) {
       System.out.println(user.toString());
   }
}
 
 
三、完整过程 
pom.xml 中导入依赖：

    
        mysql
        mysql-connector-java
        8.0.28
    
    
        org.mybatis
        mybatis
        3.5.9
    
    
        org.springframework
        spring-jdbc
        5.3.17
    
    
        org.aspectj
        aspectjweaver
        1.9.9
    
    
        org.mybatis
        mybatis-spring
        2.0.7
    
    
        org.projectlombok
        lombok
        1.18.22
    

 
写pojo实体类：
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private int id;
    private String name;
    private int tid;
}
 
写Mapper接口：
public interface UserMapper {
    public List selectUser();
}
 
写Mapper.xml：



    
        select * from school.student;
    

public class UserMapperImpl extends SqlSessionDaoSupport implements UserMapper{
    @Override
    public List selectUser() {
        return getSqlSession().getMapper(UserMapper.class).selectUser();
    }
}

public class MyTest {
    @Test
    public void test01(){
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserMapperImpl userMapperImpl = context.getBean("userMapperImpl", UserMapperImpl.class);
        List users = userMapperImpl.selectUser();
        for (User user : users) {
            System.out.println(user);
        }
    }
}

前置阅读1 —— Spring开发：https://blog.csdn.net/qq_38107282/article/details/123853828
前置阅读2 —— Spring事务：https://blog.csdn.net/qq_38107282/article/details/124569918
前置阅读3 —— Mybatis开发：https://blog.csdn.net/qq_38107282/article/details/124535569