分页

1、分页结果集对象

package com.leyou.common.pojo;

import java.util.List;

public class PageResult<T> {
    private Long total; // 总条数
    private Integer totalPage;  // 总页数
    private List<T> items;

    public Long getTotal() {
        return total;
    }

    public void setTotal(Long total) {
        this.total = total;
    }

    public Integer getTotalPage() {
        return totalPage;
    }

    public void setTotalPage(Integer totalPage) {
        this.totalPage = totalPage;
    }

    public List<T> getItems() {
        return items;
    }

    public void setItems(List<T> items) {
        this.items = items;
    }
}

2、前端请求

getDataFromServer() { // 从服务的加载数的方法。
        // 发起请求
        this.$http.get("/item/brand/page", {
          params: {
            key: this.search, // 搜索条件
            page: this.pagination.page,// 当前页
            rows: this.pagination.rowsPerPage,// 每页大小
            sortBy: this.pagination.sortBy,// 排序字段
            desc: this.pagination.descending// 是否降序
          }
        }).then(resp => { // 这里使用箭头函数
          this.brands = resp.data.items;
          this.totalBrands = resp.data.total;
          // 完成赋值后，把加载状态赋值为false
          this.loading = false;
        })
      }

3、POJO

package com.leyou.item.pojo;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Table(name = "tb_brand")
public class Brand {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;    // 品牌名称
    private String image;   // 品牌图片
    private Character letter;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

    public Character getLetter() {
        return letter;
    }

    public void setLetter(Character letter) {
        this.letter = letter;
    }
}

4、Mapper

package com.leyou.item.mapper;

import com.leyou.item.pojo.Brand;
import tk.mybatis.mapper.common.Mapper;

public interface BrandMapper extends Mapper<Brand> {
}

5、Service

package com.leyou.item.service;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.leyou.common.pojo.PageResult;
import com.leyou.item.mapper.BrandMapper;
import com.leyou.item.pojo.Brand;
import org.apache.commons.lang.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import tk.mybatis.mapper.entity.Example;

import java.util.List;

@Service
public class BrandService {
    @Autowired
    private BrandMapper brandMapper;

    /**
     * 根据查询条件分页，并排序查询品牌信息
     *
     * @param key
     * @param page
     * @param rows
     * @param sortBy
     * @param desc
     * @return
     */
    public PageResult<Brand> queryBrandsByPage(String key, Integer page, Integer rows, String sortBy, Boolean desc) {
        // 0、初始化Example对象
        Example example = new Example(Brand.class);
        Example.Criteria criteria = example.createCriteria();
        // 1、根据name模糊查询，或者根据首字母查询
        if (StringUtils.isNotBlank(key)) {
            criteria.andLike("name", "%" + key + "%").orEqualTo("letter", key);
        }
        // 2、添加分页条件
        PageHelper.startPage(page, rows);
        // 3、添加排序条件
        if (StringUtils.isNotBlank(sortBy)) {
            example.setOrderByClause(sortBy + " " + (desc ? "desc" : "asc"));
        }
        List<Brand> brands = this.brandMapper.selectByExample(example);
        // 4、包装成PageInfo对象
        PageInfo<Brand> pageInfo = new PageInfo<>(brands);
        // 5、包装成分页结果集对象
        return new PageResult<>(pageInfo.getTotal(), pageInfo.getList());
    }
}

6、Controller

package com.leyou.item.controller;

import com.leyou.common.pojo.PageResult;
import com.leyou.item.pojo.Brand;
import com.leyou.item.service.BrandService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.CollectionUtils;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

@Controller
@RequestMapping("/brand")
public class BrandController {
    @Autowired
    private BrandService brandService;

    /**
     * 根据查询条件分页，并排序查询品牌信息
     * @param key
     * @param page
     * @param rows
     * @param sortBy
     * @param desc
     * @return
     */
    @GetMapping("/page")
    public ResponseEntity<PageResult<Brand>> queryBrandsByPage(
            @RequestParam(value = "key", required = false) String key,
            @RequestParam(value = "page", defaultValue = "1") Integer page,
            @RequestParam(value = "rows", defaultValue = "5") Integer rows,
            @RequestParam(value = "sortBy", required = false) String sortBy,
            @RequestParam(value = "desc", required = false) Boolean desc
    ) {
        PageResult<Brand> result = this.brandService.queryBrandsByPage(key, page, rows, sortBy, desc);
        if (CollectionUtils.isEmpty(result.getItems())) {
            return ResponseEntity.notFound().build();
        }
        return ResponseEntity.ok(result);
    }
}