java中的分页？ [英] pagination in java?

问题描述

我希望数字以这种格式显示..

i want the numbers to be displayed in this format..

1 2 3 4 5
^

如果我在哪里按5，然后它应显示从5到10

1 2 3 4 5 ^
where if i press 5, then it should display from 5 to 10

5 6 7 8 9 10

5 6 7 8 9 10

直到最大记录可用。我只是想知道如何显示数字。

till the max records are available. i just want to know a how to do this for displaying numbers.

推荐答案

通常，您希望数据库为分页和排序做繁重的工作。以MySQL为例，你可以通过添加

Normally you want your database to do the heavy lifting for pagination and sorting. With MySQL for example you can get a page of results sorted by date by adding

ORDER BY date ASC LIMIT 5,5

到SQL查询结束时。如果您使用hibernate，您可以使用条件API以独立于供应商的方式执行此操作：

to the end of your SQL query. If you use hibernate you can do this in a vendor-independent way using the criteria API:

List<MyDomainClass> results = (List<MyDomainClass>) getSession()     
.createCriteria(MyDomainClass.class)
.setFirstResult(5)
.setMaxResults(5)
.addOrder(Order.asc("date"))
.list();

要显示分页导航，您还需要计算结果总数，以了解其中有多少页是：

To display a pagination navigation you also need to count the total number of results to know how many pages there are:

int count = (int) getSession()     
.createCriteria(MyDomainClass.class)
.setProjection(Projections.rowCount())
.list().get(0);

您可以为这两个搜索添加限制，例如，当您要对可添加的姓氏进行过滤时：

You can add restrictions to both searches, for example when you want to filter on lastname you could add:

.add(Restrictions.eq("lastname", "Smith")

（这需要添加到计数查询和列表查询中）。

(This needs to be added to both the count query and the list query).

当您知道结果总数，页面大小和当前页码时，您可以计算结果范围，如下所示：

When you know the total number of results, the pagesize and the current page number you can calculate the range of results like this :

// TODO: execute the count query here to determine totalResults
int totalPages = Math.ceil(totalResults / pageSize);
// show first page by default
int firstResult = 0;
if (currentPage >= 0 && currentPage < totalPages) {
    firstResult = currentPage * pageSize;    
}
// the number of items might be less than the page size (i.e. on the last page)
int count = Math.min(pageSize, totalResults - firstResult);        
// TODO: execute the list query here to get a page of data

如何显示导航由您决定。一些框架具有标准组件。否则，您将不得不考虑处理大量页面的方法。一种常见的方法是显示一系列的10个页码和向前/向后跳转以开始/跳转到结束链接。

How you display the navigation is up to you. Some frameworks have standard components for that. Otherwise you will have to think of a way to handle huge amounts of pages. A common approach is to show a range of say 10 page numbers and forward/backward jump to start/jump to end links.

希望这会有所帮助。

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