目录
一、前置工作:
1.整体项目目录结构
2.创建普通javamaven项目。
3.导入依赖,改造成springboot项目
4.配置启动类
5.创建service接口及其实现类
6.创建接口Mapper
7.配置数据源
8.创建数据库表
二、使用MP(mybatisplus)的分页插件
二、使用自定义的分页插件
MyBatis Plus自带分页插件,只要简单的配置即可实现分页功能。
一、前置工作:
1.整体项目目录结构
2.创建普通javamaven项目。
3.导入依赖,改造成springboot项目
依赖:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.qcby</groupId>
<artifactId>SpringBootMybatisPlus</artifactId>
<version>1.0-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.0</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.1</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
<scope>runtime</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
4.配置启动类
package com.qcby;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan("com.qcby.SpringBoot.mapper")
public class SpringBootApplication1 {
public static void main(String[] args) {
SpringApplication.run(SpringBootApplication1.class, args);
}
}
5.配置实体类
package com.qcby.SpringBoot.pojo;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
@Data
@TableName("t_product")
public class Product {
private Long id;
private String name;
private Integer price;
private Integer version;
}
package com.qcby.SpringBoot.pojo;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableLogic;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data //set和get方法
@AllArgsConstructor //全参构造器
@NoArgsConstructor //无参构造器
@TableName("t_user")
public class User {
//因为用到雪花算法,所以用Long属性
@TableId
private Long id;
private String name;
private Integer age;
private String email;
@TableLogic
private Integer isDeleted;
}
5.创建service接口及其实现类
package com.qcby.SpringBoot.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.qcby.SpringBoot.pojo.User;
/**
* UserService继承IService模板提供的基础功能
*/
public interface UserService extends IService<User> {
}
package com.qcby.SpringBoot.service.Impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.qcby.SpringBoot.mapper.UserMapper;
import com.qcby.SpringBoot.pojo.User;
import com.qcby.SpringBoot.service.UserService;
import org.springframework.stereotype.Service;
/**
* ServiceImpl实现了IService,提供了IService中基础功能的实现
* 若ServiceImpl无法满足业务需求,则可以使用自定的UserService定义方法,并在实现类中实现
*/
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}
6.创建接口Mapper
package com.qcby.SpringBoot.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.qcby.SpringBoot.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
@Mapper
public interface UserMapper extends BaseMapper<User> {
}
package com.qcby.SpringBoot.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.qcby.SpringBoot.pojo.Product;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface ProductMapper extends BaseMapper<Product> {
}
7.配置数据源
在application.yaml中配置信息。
spring:
# 配置数据源信息
datasource:
# 配置数据源类型
type: com.zaxxer.hikari.HikariDataSource
# 配置连接数据库信息
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/mybatis_plus?characterEncoding=utf-8&useSSL=false
username: root
password: root
# 配置MyBatis日志
mybatis-plus:
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
8.创建数据库表
二、使用MP(mybatisplus)的分页插件
首先要在容器中配置一个mybatisplus分页插件的bean。
可以自定义一个配置类,也可以在启动类中配置,因为启动类也是一个配置类。
package com.qcby.SpringBoot.config;
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MybatisPlusConfig {
/**
* 分页插件
* 构建一个拦截来处理分页
* 每个数据库厂商对于分页的实现语法有差别,因此,在声明该拦截时,需要指定应用的数据库类型
* @return
*/
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
interceptor.addInnerInterceptor(new
PaginationInnerInterceptor(DbType.MYSQL));//由于各个数据库的语法会有差别,因此,要指明数据库类型
return interceptor;
}
}
编写测试类
package com.qcby;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.qcby.SpringBoot.mapper.ProductMapper;
import com.qcby.SpringBoot.mapper.UserMapper;
import com.qcby.SpringBoot.pojo.Product;
import com.qcby.SpringBoot.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTest
public class Test2 {
@Autowired
private UserMapper userMapper;
@Autowired
private ProductMapper productMapper;
@Test
public void testPage(){
//设置分页参数
Page<User> page = new Page<>(1, 5);
userMapper.selectPage(page, null);
//获取分页数据
List<User> list = page.getRecords();
list.forEach(System.out::println);
System.out.println("当前页:"+page.getCurrent());
System.out.println("每页显示的条数:"+page.getSize());
System.out.println("总记录数:"+page.getTotal());
System.out.println("总页数:"+page.getPages());
System.out.println("是否有上一页:"+page.hasPrevious());
System.out.println("是否有下一页:"+page.hasNext());
}
}
二、使用自定义的分页插件
在usermapper中加入方法
package com.qcby.SpringBoot.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.qcby.SpringBoot.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
@Mapper
public interface UserMapper extends BaseMapper<User> {
/**
* 根据年龄查询用户列表,分页显示
* @param page 分页对象 ,xml中可以从里面进行取值 ,传递参数 Page 即自动分页 ,必须放在第一位
* @param age 年龄
* @return
*/
/**
* 不用加limit语句,因为配置了一个拦截的插件,只需要传入page对象,还是使用的MP的分页插件
* @param page
* @param age
* @return
*/
@Select("SELECT id,name,age,email FROM t_user WHERE age > #{age}")
IPage<User> selectPageVo(@Param("page") Page<User> page, @Param("age") Integer age);
}
package com.qcby;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.qcby.SpringBoot.mapper.ProductMapper;
import com.qcby.SpringBoot.mapper.UserMapper;
import com.qcby.SpringBoot.pojo.Product;
import com.qcby.SpringBoot.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTest
public class Test2 {
@Autowired
private UserMapper userMapper;
@Autowired
private ProductMapper productMapper;
@Test
public void testSelectPageVo(){
//设置分页参数
Page<User> page = new Page<>(1, 5);
userMapper.selectPageVo(page, 20);
//获取分页数据
List<User> list = page.getRecords();
list.forEach(System.out::println);
System.out.println("当前页:"+page.getCurrent());
System.out.println("每页显示的条数:"+page.getSize());
System.out.println("总记录数:"+page.getTotal());
System.out.println("总页数:"+page.getPages());
System.out.println("是否有上一页:"+page.hasPrevious());
System.out.println("是否有下一页:"+page.hasNext());
}
}