MyBatis-Plus6--MyBatis中的分页插件

1.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

2.默认分页

a. 添加配置类

方式一：直接添加一个配置类

package com.qcby.mybatisPlusTest.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@MapperScan("com.qcby.mybatisPlusTest.mapper")  //可以将主类中的注解移到此处
public class MybatisPlusConfig {

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new
                PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }

}

方式二：在启动类直接设置

package com.qcby;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@MapperScan("com.qcby.mybatisPlusTest.mapper")
public class MybatisPlusTestApplication {
    public static void main(String[] args) {
        SpringApplication.run(MybatisPlusTestApplication.class, args);
    }

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new
                PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }

}

b.测试

编写测试类

package com.qcby.mybatisPlusTest;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.qcby.mybatisPlusTest.mapper.UserMapper;
import com.qcby.mybatisPlusTest.model.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 MybatisPlusPageTest {
    @Autowired
    private UserMapper userMapper;

    @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());
    }
}

测试结果

3.xml自定义分页

a. UserMapper中定义接口方法

package com.qcby.mybatisPlusTest.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.mybatisPlusTest.model.User;
import org.apache.ibatis.annotations.Param;

/**
 * BaseMapper模仿向上抽取的思想
 */
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 */
    IPage<User> selectPageVo(@Param("page") Page<User> page, @Param("age") Integer age);

}

b. UserMapper.xml中编写SQL

XML 复制代码

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.qcby.mybatisPlusTest.mapper.UserMapper">
    <!--SQL 片段，记录基础字段-->
    <sql id="BaseColumns">id,username,age,email</sql>

    <!--IPage<User> selectPageVo(Page<User> page, Integer age);-->
    <select id="selectPageVo" resultType="User">
        SELECT <include refid="BaseColumns"></include> FROM t_user WHERE age > #{age}
    </select>
</mapper>

c. 设置类型别名扫描的包

XML 复制代码

mybatis-plus:
    #配置类型别名所对应的包
  type-aliases-package: com.qcby.mybatisPlusTest.model

d. 编写测试代码

XML 复制代码

 @Test
    public void testSelectPageVo(){
        //设置分页参数
        Page<User> page = new Page<>(1, 5);
        //查询 age>20 的记录进行分页
        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());
    }

执行结果

测试完成！！