mysql分页插件springboot_springboot整合mybatis+通用mapper+分页插件

引入依赖

org.mybatis.spring.boot

mybatis-spring-boot-starter

2.0.0

tk.mybatis

mapper-spring-boot-starter

2.0.0

mysql

mysql-connector-java

runtime

com.alibaba

druid-spring-boot-starter

1.1.14

com.github.pagehelper

pagehelper-spring-boot-starter

1.2.10

修改配置文件

server:

port: 8080

spring:

datasource:

type: com.alibaba.druid.pool.DruidDataSource

driver-class-name: com.mysql.jdbc.Driver

url: jdbc:mysql://localhost:3306/admin?useUnicode=true&characterEncoding=UTF-8&useSSL=false

username: root

password: root

mybatis:

#加载mapper文件

mapper-locations: classpath:mapper/*.xml

#设置实体类别名

#type-aliases-package: demo.springboot.mybatismapperpagehelper.domain

#加载mybatis全局配置文件

#config-location: classpath:mybatis/SqlMapConfig.xml

mapper:

#通用mapper的类，可以多个，不要和业务dao放到一起

mappers: demo.springboot.mybatismapperpagehelper.basedao.BaseMapper

BaseMapper

//继承tkmapper中的接口，更多可查看官方文档

//Mapper是基础的增删改查，根据Example查询等

//MySqlMapper是对mysql的一些操作

public interface BaseMapper extends Mapper, MySqlMapper {

}

实体类

@Data

public class SysUser {

//根据主键查询时必须要有@Id注解，否则会报错

@Id

private Long id;

private String username;

private String password;

private String nickname;

private Integer age;

}

DAO

//继承第三步中的BaseMapper，泛型是实体类

public interface SysUserDAO extends BaseMapper {

}

扫描dao

@SpringBootApplication

//这里使用的扫描注解不是mybatis的，是通用mapper的注解

@MapperScan("demo.springboot.mybatismapperpagehelper.dao")

public class MybatisMapperPagehelperApplication {

public static void main(String[] args) {

SpringApplication.run(MybatisMapperPagehelperApplication.class, args);

}

}

测试

@RunWith(SpringRunner.class)

@SpringBootTest

public class MybatisMapperPagehelperApplicationTests {

@Autowired

private SysUserDAO userDAO;

@Test

public void testSelectByPrimaryKey() {

//根据主键查询

SysUser sysUser = userDAO.selectByPrimaryKey(1L);

System.out.println(sysUser);

}

@Test

public void testSelectAll() {

//查询所有数据

List sysUsers = userDAO.selectAll();

System.out.println(sysUsers);

}

@Test

public void testPageHelper(){

//第一个参数为页数，第二个为条数。对这个方法后的第一个sql生效，

//单表分页，一对一分页正确。一对多，多对多分页会出现错误

//PageHelper.startPage(1, 10);

//根据id倒序排序

PageHelper.startPage(1, 2, "id desc");

List sysUsers = userDAO.selectAll();

//获取分页数据

PageInfo pageInfo = new PageInfo<>(sysUsers);

//获取总条数

System.out.println(pageInfo.getTotal());

//获取分页页数

System.out.println(pageInfo.getPageNum());

//获取分页条数

System.out.println(pageInfo.getPageSize());

//获取分页数据，即上面查询到的sysUsers

System.out.println(pageInfo.getList());

}

}

测试根据主键查询

控制台日志：

==> Preparing: SELECT id,username,password,nickname,age FROM sys_user WHERE id = ?

==> Parameters: 1(Long)

<== Total: 1

测试查询所有数据

控制台日志：

==> Preparing: SELECT id,username,password,nickname,age FROM sys_user

==> Parameters:

<== Total: 3

测试分页插件

控制台日志：

==> Preparing: SELECT id, username, password, nickname, age FROM sys_user order by id desc LIMIT ?

==> Parameters: 2(Integer)

<== Total: 2

注：通用mapper只能做一些简单的操作，业务复杂的还需要自己手动实现。

分页插件不需要格式化页数((pageNum-1)*pageSize),自己写sql时需要格式化页数

作者公众号