PageUtils.java
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package com.canrd.webmagic.common.utils;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.canrd.webmagic.domain.vo.BasePageVO;
import org.springframework.util.CollectionUtils;
import java.io.Serializable;
import java.util.*;
/**
* @Author: dengbin
* @Date: 2020/9/11
* 分页工具类
*/
public class PageUtils implements Serializable {
private static final long serialVersionUID = 4359709211352400087L;
private static final String PAGE_INDEX = "pageNo";
private static final String PAGE_SIZE = "pageSize";
private static final String TOTAL_ROWS = "total";
private static final String TOTAL_PAGES = "pages";
private static final String RECORDS = "records";
private static final int DEFAULT_PAGE_INDEX = 1;
private static final int DEFAULT_PAGE_SIZE = 10;
private static final int DEFAULT_MAP_CAPACITY = 5;
/**
* 统一分页返回对象
*
* @param list
* @return
*/
public static Map<String, Object> getUnifiedPageReturn(IPage list) {
if (list == null) {
return getUnifiedEmptyPage(DEFAULT_PAGE_INDEX, DEFAULT_PAGE_SIZE);
}
Map<String, Object> resultMap = new HashMap<>(DEFAULT_MAP_CAPACITY);
resultMap.put(PAGE_INDEX, list.getCurrent());
resultMap.put(PAGE_SIZE, list.getSize());
resultMap.put(RECORDS, list.getRecords());
resultMap.put(TOTAL_PAGES, list.getPages());
resultMap.put(TOTAL_ROWS, list.getTotal());
return resultMap;
}
/**
* 返回空分页信息给前端
* 返回空或其他字段不满足前端要求，会报错
*
* @return
*/
public static Map<String, Object> getUnifiedEmptyPage(int pageIndex, int pageSize) {
Map<String, Object> resultMap = new HashMap<>(DEFAULT_MAP_CAPACITY);
resultMap.put(PAGE_INDEX, pageIndex);
resultMap.put(PAGE_SIZE, pageSize);
resultMap.put(RECORDS, new ArrayList<>());
resultMap.put(TOTAL_PAGES, 0);
resultMap.put(TOTAL_ROWS, 0);
return resultMap;
}
public static Map<String, Object> getUnifiedEmptyPage(BasePageVO pageVO) {
return getUnifiedEmptyPage(pageVO.getCurrent(), pageVO.getSize());
}
/**
* 将旧的分页转换成新的分页对象
*
* @param oldPage 旧的分页对象，例如：xxDo的分页对象
* @param records 新的分页对象，例如：xxVo的分页对象
* @param <T> 新的分页对象的类型
* @return 统一的返回的分页对象
*/
public static <T> Map<String, Object> transferPage(IPage<?> oldPage, List<T> records) {
Page<T> newPage = new Page<>();
newPage.setCurrent(oldPage.getCurrent());
newPage.setSize(oldPage.getSize());
newPage.setRecords(records);
newPage.setPages(oldPage.getPages());
newPage.setTotal(oldPage.getTotal());
return getUnifiedPageReturn(newPage);
}
/**
* 统一分页返回对象
*
* @param records 分页数据
* @param pageVO 分页参数
* @return
*/
public static Map<String, Object> getPageReturn(List records, BasePageVO pageVO) {
if (records == null) {
return getUnifiedEmptyPage(DEFAULT_PAGE_INDEX, DEFAULT_PAGE_SIZE);
}
if (CollectionUtils.isEmpty(records)) {
return getUnifiedEmptyPage(Math.toIntExact(pageVO.getCurrent()), Math.toIntExact(pageVO.getSize()));
}
Map<String, Object> resultMap = new HashMap<>(DEFAULT_MAP_CAPACITY);
resultMap.put(PAGE_INDEX, pageVO.getCurrent());
resultMap.put(PAGE_SIZE, pageVO.getSize());
resultMap.put(RECORDS, records);
resultMap.put(TOTAL_PAGES, (pageVO.getTotal() + pageVO.getSize() - 1) / pageVO.getSize());
resultMap.put(TOTAL_ROWS, pageVO.getTotal());
return resultMap;
}
public static <T> Page<T> getRAMPageReturn(Integer current, Integer size, List<T> records) {
if (Objects.isNull(current)) {
current = 1;
}
if (Objects.isNull(size)) {
size = 10;
}
int startIndex = (current - 1) * size;
int endIndex = Math.min(current * size, records.size());
if (startIndex > endIndex) {
startIndex = endIndex;
}
Page<T> page = new Page<>();
page.setCurrent(current);
page.setSize(size);
page.setRecords(records.subList(startIndex, endIndex));
int totalPages = size == 0 ? 0 : records.size() % size == 0 ? (records.size() / size) : (records.size() / size + 1);
page.setPages(totalPages);
page.setTotal(records.size());
return page;
}
}