springboot和mybatis实现分页查询

以下是SpringBoot和MyBatis实现分页查询的步骤：

1.在pom.xml文件中引入MyBatis和PageHelper的依赖包：

<!-- 引入MyBatis依赖 -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.4</version>
</dependency>

<!-- 引入MyBatis 分页插件pageHelper -->
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.3</version>
</dependency>

2.在application.properties文件中配置PageHelper：

# PageHelper配置
pagehelper.helperDialect=mysql
pagehelper.reasonable=true
pagehelper.supportMethodsArguments=true
pagehelper.params=count=countSql

3.在Mapper.xml文件中编写分页查询的SQL语句：

<!-- 分页查询 -->
<select id="selectByPage" resultType="com.example.demo.entity.User">
    select * from user
    <where>
        <if test="name != null and name != ''">
            and name like concat('%', #{name}, '%')
        </if>
    </where>
    order by id desc
</select>

4.在Service层中调用Mapper的分页查询方法：

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public PageInfo<User> selectByPage(Integer pageNum, Integer pageSize, String name) {
        PageHelper.startPage(pageNum, pageSize);
        List<User> userList = userMapper.selectByPage(name);
        return new PageInfo<>(userList);
    }
}

5.在Controller层中接收前端传来的分页参数，并调用Service层的分页查询方法：

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/users")
    public PageInfo<User> selectByPage(@RequestParam(defaultValue = "1") Integer pageNum,
                                       @RequestParam(defaultValue = "10") Integer pageSize,
                                       String name) {
        return userService.selectByPage(pageNum, pageSize, name);
    }
}