电商网站建设开题报告seo外包资讯

不知道大家在开发中有没有遇到这种情况，就是要分页返回给前端数据，但是每页展示的数据 类型又是不一样的

 如：电商平台的商品瀑布流，可能会有自营和非自营商品的区别，那么每页展示的数据需要一部分为自营商品，一部分为非自营的商品，那这个时候后端要给的数据就需要动些脑子了，这个需求是小编实实在在遇到的需求，当初为了实现在百度和谷歌找了个遍也没找到相关的思路

 话不多说，上代码，希望有人能用得到

import lombok.Data;import java.io.Serializable;/*** <p>*     说明: 比率分页请求参数* </p>** @author Z.jc* @version 1.0.0* @since 2020/8/30*/
@Data
public class RatioPaginationParam implements Serializable {private static final long serialVersionUID = -1496754980781572809L;/*** 总条数*/private int allCount;/*** 优先总条数 如自营于非自营商品 自营商品优先/或非自营商品优先，自己理清楚*/private int priorityCount;/*** 优先数据每页展示长度比率 （重点：优先数据比率）*/private int ratio;/*** 当前页 用户请求当前页*/private int current;/*** 每页展示 用户请求每页展示*/private int pageSize;
}

import lombok.Data;import java.io.Serializable;/*** <p>说明:</p>** @author Z.jc* @version 1.0.0* @since 2020/8/30*/
@Data
public class RatioPagination implements Serializable {private static final long serialVersionUID = 6722234949377171106L;/*** 优先 limit 开始*/private int priorityLimitStart;/*** 优先limit 长度*/private int prioritySize;/*** 非优先limit 开始*/private int nonPriorityLimitStart;/*** 非优先limit 长度*/private int nonPrioritySize;public RatioPagination(int priorityLimitStart,int prioritySize,int nonPriorityLimitStart,int nonPrioritySize){this.priorityLimitStart = priorityLimitStart;this.prioritySize = prioritySize;this.nonPriorityLimitStart = nonPriorityLimitStart;this.nonPrioritySize = nonPrioritySize;}
}

/*** <p>*     说明: 商品分组工具类* </p>** @author Z.jc* @version 1.0.0* @since 2020/8/30*/
public class GroupGoodsUtil {private GroupGoodsUtil(){}/*** 数据比对* @param num1 对比值1* @param num2 对比值2* @return 返回结果值 1:num1 gt num2  0:num1 eq num2 -1:num1 lt num2*/public static Integer contrast(int num1,int num2){return Integer.compare(num1, num2);}/*** 计算分页参数* <p>若使用该方法计算分页参数，请使用limit 查询list 自己封装到pageResult </p>* @param param 计算分页参数 请求参数* @return 返回比率分页参数*/public static RatioPagination ratioPaginationCalculation(RatioPaginationParam param){//优先每页展示率算出当前页展示sizeint priorityPageSize = Math.toIntExact((long)param.getRatio() * param.getPageSize() / 10000);//计算优先总页数int priorityPageCount = (param.getPriorityCount() + priorityPageSize - 1) / priorityPageSize;//计算非优先总条数int nonPriorityCount = param.getAllCount() - param.getPriorityCount();//计算非优先每页展示int nonPriorityPageSize = param.getPageSize() - priorityPageSize;//计算非优先总页数int nonPriorityPageCount = (nonPriorityCount + nonPriorityPageSize - 1)/nonPriorityPageSize;int contrastResult = contrast(priorityPageCount,nonPriorityPageCount);int priorityLimitStart = -1;int prioritySize = -1;int nonPriorityLimitStart = -1;int nonPrioritySize = -1;switch (contrastResult){//优先页小于非优先页case -1://当前页小于优先页总页数，可进行正常比率查询if (param.getCurrent() < priorityPageCount) {//优先每页长度 * 到上一页页书 = 当前页开始indexpriorityLimitStart = priorityPageSize * (param.getCurrent() - 1);prioritySize = priorityPageSize;nonPriorityLimitStart = nonPriorityPageSize * (param.getCurrent() -1);nonPrioritySize = nonPriorityPageSize;return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);}//当前页大于优先页总页数，代表优先数据已全部展示完毕，当前页不考虑比率，全部取非优先数据if (param.getCurrent() > priorityPageCount) {//优先页pageSize * 优先页pageCount - 优先页Count = 优先页末页缺失条数int priorityLastPageDefect = priorityPageSize * priorityPageCount - param.getPriorityCount();//优先总页*非优先每页展示量 + 优先页缺失条数 = 优先页结束时非优先已展示数据总量int priorityEndNonPriorityCount = priorityPageCount * nonPriorityPageSize + priorityLastPageDefect;//优先分页结束后到当前页上一页非优先的展示总数int afterEndCount = (param.getCurrent() - 1 - priorityPageCount) * param.getPageSize();nonPriorityLimitStart = priorityEndNonPriorityCount + afterEndCount;nonPrioritySize = param.getPageSize();return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);}//当前页等于优先页总数 则代表当前页为优先页末页，需要考虑优先数据是否满足比率要求数量，若不满足则用非优先数据补齐if (param.getCurrent() == priorityPageCount) {//优先页pageSize * 优先页pageCount - 优先页Count = 优先页末页缺失条数int priorityLastPageDefect = priorityPageSize * priorityPageCount - param.getPriorityCount();priorityLimitStart = priorityPageSize * (param.getCurrent() - 1);prioritySize = priorityPageSize - priorityLastPageDefect;nonPriorityLimitStart = nonPriorityPageSize * (param.getCurrent() -1);nonPrioritySize = nonPriorityPageSize + priorityLastPageDefect;return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);}throw new CustomException(ResultCode.INVOKE_EXCEPTION,"分页参数计算错误");case 0://优先页等于非优先页 正常返回priorityLimitStart = priorityPageSize * (param.getCurrent() - 1);prioritySize = priorityPageSize;nonPriorityLimitStart = nonPriorityPageSize * (param.getCurrent() -1);nonPrioritySize = nonPriorityPageSize;return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);case 1://优先页大于非优先页 则通过非优先页进行分页参数计算// 当前页小于非优先页 正常按比率返回if (param.getCurrent() < nonPriorityPageCount) {//优先每页长度 * 到上一页页书 = 当前页开始indexpriorityLimitStart = priorityPageSize * (param.getCurrent() - 1);prioritySize = priorityPageSize;nonPriorityLimitStart = nonPriorityPageSize * (param.getCurrent() -1);nonPrioritySize = nonPriorityPageSize;return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);}//若当前页大于非优先页 则当前页完全返回优先数据 不考虑比率if (param.getCurrent() > nonPriorityPageCount) {//非优先页pageSize * 非优先页pageCount - 非优先页Count = 非优先页末页缺失条数int nonPriorityLastPageDefect = nonPriorityPageSize * nonPriorityPageCount - nonPriorityCount;//非优先总页*优先每页展示量 + 非优先页缺失条数 = 非优先页结束时优先已展示数据总量int nonPriorityEndPriorityCount = nonPriorityPageCount * priorityPageSize + nonPriorityLastPageDefect;//非优先分页结束后到当前页上一页优先的展示总数int afterEndCount = (param.getCurrent() - 1 - nonPriorityPageCount) * param.getPageSize();priorityLimitStart = nonPriorityEndPriorityCount + afterEndCount;prioritySize = param.getPageSize();return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);}//若当前页等于非优先页，则考虑非优先数据是否满足比率数量，不满足则用优先商品数据补齐if (param.getCurrent() == nonPriorityPageCount) {//优先页pageSize * 优先页pageCount - 优先页Count = 优先页末页缺失条数int nonPriorityLastPageDefect = nonPriorityPageSize * nonPriorityPageCount - nonPriorityCount;priorityLimitStart = priorityPageSize * (param.getCurrent() - 1);prioritySize = priorityPageSize + nonPriorityLastPageDefect;nonPriorityLimitStart = nonPriorityPageSize * (param.getCurrent() -1);nonPrioritySize = nonPriorityPageSize - nonPriorityLastPageDefect;return new RatioPagination(priorityLimitStart,prioritySize,nonPriorityLimitStart,nonPrioritySize);}throw new CustomException(ResultCode.INVOKE_EXCEPTION,"分页参数计算错误");default:throw new CustomException(ResultCode.INVOKE_EXCEPTION,"分页参数计算错误");}}}

以上就是完整的代码了，通过已知参数，计算出当前页两种类型的数据各自的limit参数，然后进行sql limit查询，就可以得到想要的数据啦

此工具类不仅适用于sql查询，同样适用于redis zset查询