基于hibernate实现的分页技术

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。