Very useful paging tool
#When we do queries, we often return a list of objects. When the size of the list is relatively large, paging is often used.
1.Introduce dependencies into the pom file
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>5.1.4</version>
</dependency>
2.Introduce paging tool class
package com.creaditx.adnetworkbackend.common.utils;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import java.util.LinkedList;
import java.util.List;
/**
-
Custom List paging tool
-
@author lb
*/
public class PageUtil {public static PageInfo list2PageInfo(List arrayList, Integer pageNum, Integer pageSize) { //Integer listingPageHelper.startPage (pageNum, pageSize); int pageStart = pageNum == 1 ? 0 : ( pageNum - 1 ) * pageSize ; int pageEnd = arrayList.size() < pageSize * pageNum ? arrayList . size ( ) : pageSize * pageNum ; List pageResult = new LinkedList ( ) ; if ( arrayList . size ( ) > pageStart ) { pageResult = arrayList . subList ( pageStart , pageEnd ); } PageInfo pageInfo = new PageInfo(pageResult); //Create PageInfo and create pageInfo.setTotal(arrayList.size()); int endRow = pageInfo . getEndRow () == 0 ? 0 : ( pageNum - 1 ) * pageSize + pageInfo . getEndRow ( ) + 1 ; pageInfo . setEndRow ( endRow ) ;
boolean hasNextPage = arrayList.size() <= pageSize * pageNum ? false : true;
pageInfo.setHasNextPage(hasNextPage);
boolean hasPreviousPage = pageNum == 1 ? false : true;
pageInfo.setHasPreviousPage(hasPreviousPage);
pageInfo.setIsFirstPage(!hasPreviousPage);
boolean isLastPage = (arrayList.size() > pageSize * (pageNum - 1) && arrayList.size() <= pageSize * pageNum) ? true : false;
pageInfo.setIsLastPage(isLastPage);
int pages = arrayList.size() % pageSize == 0 ? arrayList.size() / pageSize : (arrayList.size() / pageSize) + 1;
pageInfo.setNavigateLastPage(pages);
int[] navigatePageNums = new int[pages];
for (int i = 1; i < pages; i++) {
navigatePageNums[i - 1] = i;
}
pageInfo.setNavigatepageNums(navigatePageNums);
int nextPage = pageNum < pages ? pageNum + 1 : 0;
pageInfo.setNextPage(nextPage);
pageInfo.setPageNum(pageNum);
pageInfo.setPageSize(pageSize);
pageInfo.setPages(pages);
pageInfo.setPrePage(pageNum - 1);
pageInfo.setSize(pageInfo.getList().size());
int starRow = arrayList.size() < pageSize * pageNum ? 1 + pageSize * (pageNum - 1) : 0;
pageInfo.setStartRow(starRow);
return pageInfo;
}
}
3.Use
private RestfulResult<ResponseEntity> getKeywords(KeywordReq keywordReq,Integer index, Integer pageSize) {
RestfulResult<ResponseEntity> restfulResult = new RestfulResult<>();
PageInfo<KeywordRes> info = PageUtil.list2PageInfo(realTimeBoardDatacollectMapper.getKeyword(keywordReq), index, pageSize);
List<KeywordExcel> KeywordExcels = new ArrayList<>();
if (CollectionUtils.isNotEmpty(info.getList())) {
for (KeywordRes keywordRes : info.getList()) {
KeywordExcel keywordExcel = new KeywordExcel();
BeanUtils.copyProperties(keywordRes, keywordExcel);
KeywordExcels.add(keywordExcel);
}
}
ResponseEntity responseEntity = new ResponseEntity();
responseEntity.setList(KeywordExcels);
responseEntity.setTotal(info.getTotal());
restfulResult.setInstall(ResCode.SUCCESS, responseEntity);
return restfulResult;
}
It's so useful that I have no friends. . .
