存缓中的java-内存分页

素颜马尾好姑娘i 2024-04-17 05:26 84阅读 0赞

public class PageBySubListUtil {
    
    	/**
    	 * 分页方法
    	 * 
    	 * @param list 源数据
    	 * @param currentPage 当前页页码，从1开始记
    	 * @param pageSize 每页显示几条
    	 * @return
    	 */
    	public static <T> List<T> getPageList(List<T> list, int currentPage, int pageSize) {
            if(list == null || list.size() == 0){
                return null;
            }
            int total = list.size();
            
    		// 总页数
    		int pageNum = total % pageSize == 0 ? total / pageSize : total / pageSize + 1; //总页数
    
            if(currentPage < 1 || currentPage > pageNum){
                return null;
            }
            
    		int fromIndex = 0; // 从哪里开始截取
    		int toIndex = 0; // 截取几个
    		if (list == null || list.size() == 0) {
    			return null;
    		}
    		// 当前页小于或等于总页数时执行
    		if (currentPage <= pageNum && currentPage != 0) {
    			fromIndex = (currentPage - 1) * pageSize;
    			if (currentPage == pageNum) {
    				toIndex = list.size();
    			} else {
    				toIndex = currentPage * pageSize;
    			}
    
    		}
    		return list.subList(fromIndex, toIndex);
    	}
    	
    	
    	
    	public static void main(String[] args) {
    		List<Integer> list = new ArrayList<Integer>();
    		list.add(111);
    		list.add(222);
    		list.add(333);
    		list.add(444);
    		list.add(555);
    		list.add(666);
    		list.add(777);
    		list.add(888);
    		list.add(999);
    		list.add(1000);
    		
    		int count = list.size();
    		int currentPage =3;
    		int pageSize = 4;
    //		int pageNum = 2;
    		int totalPage=(count%pageSize==0)?(count/pageSize):(count/pageSize+1);
    		System.out.println("总页数:" + totalPage);
    		
    		List<Integer> pageList = getPageList(list, currentPage, pageSize);
    		for (Integer i : pageList) {
    			System.out.println(i);
    		}
    		
    		
    	}
    	
    }