本文实例讲述了基于hibernate实现的分页技术。分享给大家供大家参考,具体如下:
先说明一下基于hibernate实现分页的原理,假如从数据库取出100条数据,我们要让每页显示10条,假如从30开始,只需要设置起始位置和最大的返回结果即可
先上代码:注意传进来的参数有 Page这类,后面有介绍
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public List<Article> queryByPage( final String username, final Page page) { return this .getHibernateTemplate().executeFind( new HibernateCallback() { public Object doInHibernate(Session session) throws HibernateException, SQLException { Query query = session.createQuery( "select art from Article art where art.username = ?" ); //设置参数 query.setParameter( 0 , username); //设置每页显示多少个,设置多大结果。 query.setMaxResults(page.getEveryPage()); //设置起点 query.setFirstResult(page.getBeginIndex()); return query.list(); } }); |
上面关键代码是 setMaxResults(),和setFirstResult(),即设置最大显示值和起点
这里我们需要一个Page工具类,用来操作分页。
Page.java:
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package com.fenye; public class Page { // 1.每页显示数量(everyPage) private int everyPage; // 2.总记录数(totalCount) private int totalCount; // 3.总页数(totalPage) private int totalPage; // 4.当前页(currentPage) private int currentPage; // 5.起始点(beginIndex) private int beginIndex; // 6.是否有上一页(hasPrePage) private boolean hasPrePage; // 7.是否有下一页(hasNextPage) private boolean hasNextPage; public Page( int everyPage, int totalCount, int totalPage, int currentPage, int beginIndex, boolean hasPrePage, boolean hasNextPage) { this .everyPage = everyPage; this .totalCount = totalCount; this .totalPage = totalPage; this .currentPage = currentPage; this .beginIndex = beginIndex; this .hasPrePage = hasPrePage; this .hasNextPage = hasNextPage; } //构造函数,默认 public Page(){} //构造方法,对所有属性进行设置 public int getEveryPage() { return everyPage; } public void setEveryPage( int everyPage) { this .everyPage = everyPage; } public int getTotalCount() { return totalCount; } public void setTotalCount( int totalCount) { this .totalCount = totalCount; } public int getTotalPage() { return totalPage; } public void setTotalPage( int totalPage) { this .totalPage = totalPage; } public int getCurrentPage() { return currentPage; } public void setCurrentPage( int currentPage) { this .currentPage = currentPage; } public int getBeginIndex() { return beginIndex; } public void setBeginIndex( int beginIndex) { this .beginIndex = beginIndex; } public boolean isHasPrePage() { return hasPrePage; } public void setHasPrePage( boolean hasPrePage) { this .hasPrePage = hasPrePage; } public boolean isHasNextPage() { return hasNextPage; } public void setHasNextPage( boolean hasNextPage) { this .hasNextPage = hasNextPage; } } |
Page工具类主要是封装页面信息,一共多少数据啊,一页显示多少啊,起点的序号,总页数,是否有上一页下一页,当前页。
还需要一个操作page的工具类,PageUtil.java
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package com.sanqing.fenye; /* * 分页信息辅助类 */ public class PageUtil { public static Page createPage( int everyPage, int totalCount, int currentPage) { everyPage = getEveryPage(everyPage); currentPage = getCurrentPage(currentPage); int totalPage = getTotalPage(everyPage, totalCount); int beginIndex = getBeginIndex(everyPage, currentPage); boolean hasPrePage = getHasPrePage(currentPage); boolean hasNextPage = getHasNextPage(totalPage, currentPage); return new Page(everyPage, totalCount, totalPage, currentPage, beginIndex, hasPrePage, hasNextPage); } public static Page createPage(Page page, int totalCount) { int everyPage = getEveryPage(page.getEveryPage()); int currentPage = getCurrentPage(page.getCurrentPage()); int totalPage = getTotalPage(everyPage, totalCount); int beginIndex = getBeginIndex(everyPage, currentPage); boolean hasPrePage = getHasPrePage(currentPage); boolean hasNextPage = getHasNextPage(totalPage, currentPage); return new Page(everyPage, totalCount, totalPage, currentPage, beginIndex, hasPrePage, hasNextPage); } //设置每页显示记录数 public static int getEveryPage( int everyPage) { return everyPage == 0 ? 10 : everyPage; } //设置当前页 public static int getCurrentPage( int currentPage) { return currentPage == 0 ? 1 : currentPage; } //设置总页数,需要总记录数,每页显示多少 public static int getTotalPage( int everyPage, int totalCount) { int totalPage = 0 ; if (totalCount % everyPage == 0 ) { totalPage = totalCount / everyPage; } else { totalPage = totalCount / everyPage + 1 ; } return totalPage; } //设置起始点,需要每页显示多少,当前页 public static int getBeginIndex( int everyPage, int currentPage) { return (currentPage - 1 ) * everyPage; } //设置是否有上一页,需要当前页 public static boolean getHasPrePage( int currentPage) { return currentPage == 1 ? false : true ; } //设置是否有下一个,需要总页数和当前页 public static boolean getHasNextPage( int totalPage, int currentPage) { return currentPage == totalPage || totalPage == 0 ? false : true ; } } |
创建Page只需要3个参数,每页显示多少数据,当前页,总共多少数据,其他的4个参数都可以通过这三个计算出来
所以后面要创建Page,只需要调用这工具方法PageUtil.createPage(3个参数),就返回一Page.
返回的Page就是前面参数的Page,即要显示的分页
这样就算完成了分页的功能。
希望本文所述对大家基于Hibernate框架的Java程序设计有所帮助。