List 分页工具类，一劳永逸

约定不等于承诺〃 2023-06-30 04:28 18阅读 0赞

有时候经常需要对List进行分批处理，就搞个工具类，使用类似迭代器模式

package com.xiao.springcloud.demo.common.util;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 /**
 * [简要描述]: List 分页工具
 * [详细描述]:
 *
 * @author xiaolinlin
 * @version 1.0, 2020/1/15 09:38
 * @since JDK 1.8
 */
 public final class ListPageUtil<T>
 {
 private CopyOnWriteArrayList<T> list;
 private int pageSize = 0;
 private int pageCount = 0;
 private int listSize = 0;
 private int index = 0;
 
 /**
 * [简要描述]:List分页工具初始化 
 * [详细描述]: 
 *
 * @param list : 待分页的数据集
 * @param pageSize : 每页数
 * @return xiaolinlin 2020/1/15 - 10:02
 **/
 public ListPageUtil(List<T> list, int pageSize)
 {
 if (null == list || 0 == list.size())
 {
 throw new UnsupportedOperationException("List can not null!");
 }
 
 if (0 == pageSize)
 {
 throw new UnsupportedOperationException("Page size can not 0");
 }
 
 this.list = new CopyOnWriteArrayList<>(list);
 this.listSize = list.size();
 
 if (pageSize > listSize)
 {
 this.pageSize = listSize;
 }
 else
 {
 this.pageSize = pageSize;
 }
 
 this.pageCount = listSize / pageSize;
 this.pageCount = listSize % pageSize == 0 ? pageCount : pageCount + 1;
 this.index = 0;
 }
 
 /**
 * [简要描述]:获取首页 
 * [详细描述]: 
 *
 * @return java.util.List<T>
 * xiaolinlin 2020/1/15 - 10:02
 **/
 public List<T> getFistPage()
 {
 return list.subList(0, pageSize);
 }
 
 /**
 * [简要描述]:获取最后一页 
 * [详细描述]: 
 *
 * @return java.util.List<T>
 * xiaolinlin 2020/1/15 - 10:03
 **/
 public List<T> getLastPage()
 {
 return list.subList((pageCount - 1) * pageSize, listSize);
 }
 
 /**
 * [简要描述]:获取下一页 
 * [详细描述]: 
 *
 * @return java.util.List<T>
 * xiaolinlin 2020/1/15 - 10:03
 **/
 public List<T> nextPage()
 {
 List<T> subList = null;
 if (index == pageCount - 1)
 {
 subList = list.subList(index * pageSize, listSize);
 }
 else
 {
 subList = list.subList(index * pageSize, (index + 1) * pageSize);
 }
 index++;
 return subList;
 }
 
 /**
 * [简要描述]:是否有下一页 
 * [详细描述]: 
 *
 * @return boolean
 * xiaolinlin 2020/1/15 - 10:03
 **/
 public boolean hasNext()
 {
 return index < pageCount;
 }
 
 /**
 * [简要描述]:获取总页数 
 * [详细描述]: 
 *
 * @return int
 * xiaolinlin 2020/1/15 - 10:03
 **/
 public int getPageCount()
 {
 return pageCount;
 }
 
 /**
 * [简要描述]:获取每页数 
 * [详细描述]: 
 *
 * @return int
 * xiaolinlin 2020/1/15 - 10:03
 **/
 public int getPageSize()
 {
 return pageSize;
 }
 
 /**
 * [简要描述]:获取当前页数 
 * [详细描述]: 
 *
 * @return int
 * xiaolinlin 2020/1/15 - 10:03
 **/
 public int getIndex()
 {
 return index + 1;
 }
 
 /**
 * [简要描述]:获取带分页的数据总数 
 * [详细描述]: 
 *
 * @return int
 * xiaolinlin 2020/1/15 - 10:04
 **/
 public int getListSize()
 {
 return listSize;
 }
 
 public static void main(String[] args)
 {
 List<Integer> list = new ArrayList<>();
 int length = 23;
 for (int i = 0; i < length; i++)
 {
 list.add(i);
 }
 int pageSize = 30;
 System.out.println(list);
 
 ListPageUtil<Integer> listPageUtil = new ListPageUtil<>(list, pageSize);
 System.out.println("List size: " + listPageUtil.getListSize());
 System.out.println("Page count: " + listPageUtil.getPageCount());
 System.out.println("Page size: " + listPageUtil.getPageSize());
 System.out.println("First page: " + listPageUtil.getFistPage());
 System.out.println("Last page: " + listPageUtil.getLastPage());
 while (listPageUtil.hasNext())
 {
 System.out.println("Page index: " + listPageUtil.getIndex());
 System.out.println("Next page: " + listPageUtil.nextPage());
 }
 
 }
 }

[GitHub地址][GitHub]

[GitHub]: https://github.com/Xlinlin/SpringCloud-Demo