ssh分页处理
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分页显示一直是web开发中一大烦琐的难题,传统的网页设计只在一个JSP或者ASP页面中书写所有关于数据库操作的代码,那样做分页可能简单一点,但当把网站分层开发后,分页就比较困难了,下面是我做Spring+Hibernate+Struts2项目时设计的分页代码,与大家分享交流。
1、DAO层接口的设计,在MemberDao接口中定义了如下两个方法:
1、DAO层接口的设计,在MemberDao接口中定义了如下两个方法:
public interface MemberDao {
//省略了其他的代码
public List queryForPage( final String hql, final int offset, final int length);
public int getAllRowCount(String hql);
}
}
2、DAO层实现类MemberDaoImpl对上面两个方法的实现如下:
public class MemberDaoImpl extends HibernateDaoSupport implements MemberDao {
//省略了其他的代码
public List queryForPage( final String hql, final int offset, final int length) {
List list = getHibernateTemplate().executeFind( new HibernateCallback() {
public Object doInHibernate(Session session) throws HibernateException,SQLException {
Query query = session.createQuery(hql);
query.setFirstResult(offset);
query.setMaxResults(length);
List list = query.list();
return list;
}
} );
return list;
}
public int getAllRowCount(String hql) {
return getHibernateTemplate().find(hql).size();
}
}
}
3、下面我们来新建一个保存分页信息的类PageBean,具体代码如下:
public class PageBean {
private List list; //要返回的某一页的记录列表
private int allRow; //总记录数
private int totalPage; //总页数
private int currentPage; //当前页
private int pageSize; //每页记录数
private boolean isFirstPage; //是否为第一页
private boolean isLastPage; //是否为最后一页
private boolean hasPreviousPage; //是否有前一页
private boolean hasNextPage; //是否有下一页
public List getList() {
return list;
}
public void setList(List list) {
this.list = list;
}
public int getAllRow() {
return allRow;
}
public void setAllRow( int allRow) {
this.allRow = allRow;
}
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 getPageSize() {
return pageSize;
}
public void setPageSize( int pageSize) {
this.pageSize = pageSize;
}
public void init() {
this.isFirstPage = isFirstPage();
this.isLastPage = isLastPage();
this.hasPreviousPage = isHasPreviousPage();
this.hasNextPage = isHasNextPage();
}
public boolean isFirstPage() {
return currentPage == 1; // 如是当前页是第1页
}
public boolean isLastPage() {
return currentPage == totalPage; //如果当前页是最后一页
}
public boolean isHasPreviousPage() {
return currentPage != 1; //只要当前页不是第1页
}
public boolean isHasNextPage() {
return currentPage != totalPage; //只要当前页不是最后1页
}
public static int countTotalPage( final int pageSize, final int allRow) {
int totalPage = allRow % pageSize == 0 ? allRow /pageSize : allRow /pageSize+1;
return totalPage;
}
public static int countOffset( final int pageSize, final int currentPage) {
final int offset = pageSize *(currentPage-1);
return offset;
}
public static int countCurrentPage( int page) {
final int curPage = (page ==0?1:page);
return curPage;
}
}
}
4、Service层接口的设计:
public interface MemberService {
//省略其他的代码
public PageBean queryForPage( int pageSize, int currentPage);
}
}
5、Service层实现类的部分内码如下:
public class MemberServiceImpl implements MemberService {
//通过applicationContext.xml配置文件注入MemberDao的值
private MemberDao memberDao;
public void setMemberDao(MemberDao memberDao) {
this.memberDao = memberDao;
}
public PageBean queryForPage( int pageSize, int page) {
final String hql = "from Member "; //查询语句
int allRow = memberDao.getAllRowCount(hql); //总记录数
int totalPage = PageBean.countTotalPage(pageSize, allRow); //总页数
final int offset = PageBean.countOffset(pageSize, page); //当前页开始记录
final int length = pageSize; //每页记录数
final int currentPage = PageBean.countCurrentPage(page);
List <Member> list = memberDao.queryForPage(hql,offset, length); //"一页"的记录
//把分页信息保存到Bean中
PageBean pageBean = new PageBean();
pageBean.setPageSize(pageSize);
pageBean.setCurrentPage(currentPage);
pageBean.setAllRow(allRow);
pageBean.setTotalPage(totalPage);
pageBean.setList(list);
pageBean.init();
return pageBean;
}
6、在Struts2中调用queryForPageMemberServic
public class ListMember extends ActionSupport {
//通过applicationContext.xml配置文件注入memberService的值
private MemberService memberService;
public void setMemberService(MemberService memberService) {
this.memberService = memberService;
}
private int page; //第几页
private PageBean pageBean; //包含分布信息的bean
public int getPage() {
return page;
}
public void setPage( int page) { //若URL中无此参数,会默认为第1页
this.page = page;
}
public PageBean getPageBean() {
return pageBean;
}
public void setPageBean(PageBean pageBean) {
this.pageBean = pageBean;
}
@Override
public String execute() throws Exception {
//分页的pageBean,参数pageSize表示每页显示记录数,page为当前页
this.pageBean = memberService.queryForPage( 2, page);
return SUCCESS;
}
}
}
7、最后在listMember.jsp页面中,用到了Struts2标签:
<s:iterator value="pageBean.list">
<s:property value="title"/>
<a href="getArticle.action?id=<s:property value=" id"/>">modify</a>
<a href="deleteArticle.action?id=<s:property value=" id"/>" onclick="return askDel()"/>delete </a><br/>
</s:iterator>
共 <s:property value="pageBean.allRow"/> 条记录
共 <s:property value="pageBean.totalPage"/> 页
当前第 <s:property value="pageBean.currentPage"/>页<br/>
<s:if test="%{pageBean.currentPage == 1}" >
第一页 上一页
</s:if>
<s:else>
<a href="listMyArticle.action?page=1">第一页</a>
<a href="listMyArticle.action?page=<s:property value=" %{pageBean.currentPage-1}"/>">上一页</a>
</s:else>
<s:if test="%{pageBean.currentPage != pageBean.totalPage}" >
<a href="listMyArticle.action?page=<s:property value=" %{pageBean.currentPage+1}"/>">下一页</a>
<a href="listMyArticle.action?page=<s:property value=" pageBean.totalPage"/>">最后一页</a>
</s:if>
<s:else>
下一页 最后一页
</s:else>
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