mysql分頁插件springboot_springboot整合mybatis+通用mapper+分頁插件

引入依賴

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

修改配置檔案

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:

#加載mapper檔案

mapper-locations: classpath:mapper/*.xml

#設定實體類别名

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

#加載mybatis全局配置檔案

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

mapper:

#通用mapper的類，可以多個，不要和業務dao放到一起

mappers: demo.springboot.mybatismapperpagehelper.basedao.BaseMapper

BaseMapper

//繼承tkmapper中的接口，更多可檢視官方文檔

//Mapper是基礎的增删改查，根據Example查詢等

//MySqlMapper是對mysql的一些操作

public interface BaseMapper extends Mapper, MySqlMapper {

}

實體類

@Data

public class SysUser {

//根據主鍵查詢時必須要有@Id注解，否則會報錯

@Id

private Long id;

private String username;

private String password;

private String nickname;

private Integer age;

}

DAO

//繼承第三步中的BaseMapper，泛型是實體類

public interface SysUserDAO extends BaseMapper {

}

掃描dao

@SpringBootApplication

//這裡使用的掃描注解不是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);

}

}

測試

@RunWith(SpringRunner.class)

@SpringBootTest

public class MybatisMapperPagehelperApplicationTests {

@Autowired

private SysUserDAO userDAO;

@Test

public void testSelectByPrimaryKey() {

//根據主鍵查詢

SysUser sysUser = userDAO.selectByPrimaryKey(1L);

System.out.println(sysUser);

}

@Test

public void testSelectAll() {

//查詢所有資料

List sysUsers = userDAO.selectAll();

System.out.println(sysUsers);

}

@Test

public void testPageHelper(){

//第一個參數為頁數，第二個為條數。對這個方法後的第一個sql生效，

//單表分頁，一對一分頁正确。一對多，多對多分頁會出現錯誤

//PageHelper.startPage(1, 10);

//根據id倒序排序

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

List sysUsers = userDAO.selectAll();

//擷取分頁資料

PageInfo pageInfo = new PageInfo<>(sysUsers);

//擷取總條數

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

//擷取分頁頁數

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

//擷取分頁條數

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

//擷取分頁資料，即上面查詢到的sysUsers

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

}

}

測試根據主鍵查詢

控制台日志：

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

==> Parameters: 1(Long)

<== Total: 1

測試查詢所有資料

控制台日志：

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

==> Parameters:

<== Total: 3

測試分頁插件

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隻能做一些簡單的操作，業務複雜的還需要自己手動實作。

分頁插件不需要格式化頁數((pageNum-1)*pageSize),自己寫sql時需要格式化頁數

作者公衆号