Mybatis 框架 ( 五 ) 分页

4.6.分页

Mybatis-plus 内置分页插件, 并支持多种数据库

官网 : 分页插件 | MyBatis-Plus (baomidou.com)

4.6.1.增加拦截器

通过 @MapperScan 指定 mapper接口的路径

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.yuan.mapper")
public class MybatisPlusConfig {

    /**
     * 添加分页插件
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));//如果配置多个插件,切记分页最后添加
        //interceptor.addInnerInterceptor(new PaginationInnerInterceptor()); 如果有多数据源可以不配具体类型 否则都建议配上具体的DbType
        return interceptor;
    }

}

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4.6.2.封装分页信息

准备封装用于分页查询的工具类 BrandInfoPage

import lombok.Data;

@Data
public class BrandInfoPage {

    private Integer pageNo = 1;
    private Integer pageSize = 10;

}
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4.6.3.serviceImpl

服务层查询

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.yuan.entity.BrandInfo;
import com.yuan.mapper.BrandInfoMapper;
import com.yuan.page.BrandInfoPage;
import com.yuan.service.BrandInfoService;
import org.springframework.stereotype.Service;


@Service
public class BrandInfoServiceImpl extends ServiceImpl<BrandInfoMapper, BrandInfo>
    implements BrandInfoService{

    @Override
    public IPage<BrandInfo> listForPage(BrandInfoPage page) {
        IPage<BrandInfo> pageInfo = new Page<>();
        // 设置页号
        pageInfo.setCurrent(page.getPageNo());
        // 设置页大小
        pageInfo.setSize(page.getPageSize());

        return baseMapper.selectPage(pageInfo, null);
    }
}
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baseMapper.selectPage(pageInfo, null); 第二个参数为 QueryWrapper 用于条件查询

4.6.4.返回 Controller类

分析数据

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.yuan.entity.BrandInfo;
import com.yuan.page.BrandInfoPage;
import com.yuan.service.BrandInfoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class BrandInfoController {

    @Autowired
    private BrandInfoService brandInfoService;

    @RequestMapping("/brandInfo/query")
    public IPage<BrandInfo> query(BrandInfoPage page){
        System.out.println("page = " + page);

        IPage<BrandInfo> list = brandInfoService.listForPage(page);
        System.out.println("list = " + list);
        
        System.out.println("分页数据集合 = " + list.getRecords());
        System.out.println("当前页号 = " + list.getCurrent());
        System.out.println("每页最多多少条 = " + list.getSize());
        System.out.println("总记录数 = " + list.getTotal());
        System.out.println("总页数 = " + list.getPages());
    }
}
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4.6.5.增加条件查询

4.6.5.1.修改 page类

import lombok.Data;

@Data
public class BrandInfoPage {

    private Integer pageNo = 1;
    private Integer pageSize = 10;

    /**
     * 中文名 模糊
     */
    private String cnName;
    /**
     * 英文名 精确
     */
    private String enName;
}
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4.6.5.2.修改ServiceImpl

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.yuan.entity.BrandInfo;
import com.yuan.mapper.BrandInfoMapper;
import com.yuan.page.BrandInfoPage;
import com.yuan.service.BrandInfoService;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;


@Service
public class BrandInfoServiceImpl extends ServiceImpl<BrandInfoMapper, BrandInfo>
    implements BrandInfoService{

    @Override
    public IPage<BrandInfo> listForPage(BrandInfoPage page) {
        IPage<BrandInfo> pageInfo = new Page<>();
        // 设置页号
        pageInfo.setCurrent(page.getPageNo());
        // 设置页大小
        pageInfo.setSize(page.getPageSize());

        LambdaQueryWrapper<BrandInfo> queryWrapper = new LambdaQueryWrapper<BrandInfo>()
                .like(page.getCnName() != null, BrandInfo::getBrandCnName, page.getCnName())
                .eq( !StringUtils.isEmpty(page.getEnName()), BrandInfo::getBrandEnName, page.getEnName())
                .orderByAsc(BrandInfo::getBrandNum)
                ;
        return baseMapper.selectPage(pageInfo, queryWrapper);
    }
}
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