Master Spring Boot & MyBatis Integration: Full Configuration and CRUD Guide

Environment: Spring Boot 2.3.11 + MyBatis 3.5.6

Dependencies

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>org.mybatis.spring.boot</groupId>
  <artifactId>mybatis-spring-boot-starter</artifactId>
</dependency>
<dependency>
  <groupId>com.github.pagehelper</groupId>
  <artifactId>pagehelper-spring-boot-starter</artifactId>
  <version>1.3.0</version>
</dependency>

Application Configuration

pagehelper:
  helperDialect: mysql
  reasonable: true
  pageSizeZero: true
  offsetAsPageNum: true
  rowBoundsWithCount: true
---
mybatis:
  type-aliases-package: com.pack.domain
  configuration:
    lazy-loading-enabled: false
    aggressive-lazy-loading: false
    logImpl: org.apache.ibatis.logging.stdout.StdOutImpl
    mapUnderscoreToCamelCase: true

Refer to the official documentation for detailed explanations of the above settings.

Pagination configuration diagram:

MyBatis configuration diagram:

Adding Mapper Scan in the Startup Class

@SpringBootApplication
@MapperScan({"com.pack.mapper"})
public class SpringBootMyBatisApplication {

  public static void main(String[] args) {
    SpringApplication.run(SpringBootMyBatisApplication.class, args);
  }
}

After adding @MapperScan, individual mapper interfaces no longer need the @Mapper annotation.

Core processing class:

MapperScannerRegistrar.java

public class MapperScannerRegistrar implements ImportBeanDefinitionRegistrar, ResourceLoaderAware {
    // implementation details omitted
}

The ImportBeanDefinitionRegistrar interface is used to dynamically register beans, similar to how EnableFeignClients registers @FeignClient -annotated classes.

Mapper Interface Definition

public interface UsersMapper {

  @Select("SELECT * FROM t_users")
  @Results(id = "users", value = {
    @Result(property = "name", column = "name", javaType = String.class),
    @Result(property = "password", column = "password")
  })
  List<Users> findAll();

  @Select("SELECT * FROM t_users WHERE id = #{id}")
  @ResultMap("users")
  Users findById(String id);

  @Insert("insert into t_users values(#{id}, #{password}, #{username})")
  int saveUsers(Users users);

  @Update("UPDATE t_users SET username = #{username}, password = #{password} WHERE id = #{id}")
  int updateUsers(Users users);

  @Delete("DELETE FROM t_users where id = #{id}")
  int deleteById(String id);

  @SelectProvider(type = UsersProvider.class, method = "selectLikeUsers")
  @ResultMap("users")
  List<Users> selectLikeUsers(Users users);

  @UpdateProvider(type = UsersProvider.class, method = "updateByProvider")
  int updateByProvider(@Param("users") Users users);
}

Adding an id attribute to @Results allows other methods to reuse the mapping via @ResultMap("users"). The @*Provider annotations enable dynamic SQL generation.

Dynamic SQL Provider

public class UsersProvider {

  public String selectLikeUsers(Users users) {
    StringBuilder sql = new StringBuilder("SELECT * FROM t_users t where 1=1 ");
    if (users.getUsername() != null && users.getUsername().trim().length() > 0) {
      sql.append(String.format("and t.username like '%s'", "%" + users.getUsername() + "%"));
    }
    return sql.toString();
  }

  public String updateByProvider(@Param("users") Users users) {
    SQL sql = new SQL();
    sql.UPDATE("t_users")
       .SET("username = #{users.username}", "password = #{users.password}")
       .WHERE("id = #{users.id}");
    return sql.toString();
  }
}

Unit Tests

@RunWith(SpringRunner.class)
@SpringBootTest
public class UsersMapperTest {

  @Resource
  private UsersMapper usersMapper;

  @Test
  public void testFindAll() {
    Page<Users> page = PageHelper.startPage(1, 2);
    usersMapper.findAll();
    System.out.println(page.getResult());
    System.out.println(page.getTotal() + "
" + page.getPages());
  }

  @Test
  public void testFindById() {
    System.out.println(usersMapper.findById("1"));
  }

  @Test
  public void testSaveUsers() {
    Users users = new Users();
    users.setId("4");
    users.setPassword("123456");
    users.setUsername("zhangsan");
    System.out.println(usersMapper.saveUsers(users));
  }

  @Test
  public void testUpdateUser() {
    Users users = new Users();
    users.setId("3");
    users.setPassword("111111");
    users.setUsername("zhangsan");
    System.out.println(usersMapper.updateUsers(users));
  }

  @Test
  public void testDeleteById() {
    System.out.println(usersMapper.deleteById("3"));
  }

  @Test
  public void testSelectLikeUsers() {
    Users users = new Users();
    users.setUsername("gu");
    System.out.println(usersMapper.selectLikeUsers(users));
  }

  @Test
  public void testUpdateByProvider() {
    Users users = new Users();
    users.setId("2");
    users.setPassword("111111");
    users.setUsername("guest");
    System.out.println(usersMapper.updateByProvider(users));
  }
}

All steps are complete.