为了避免在Action(呈现层)和Manager(业务逻辑层)之间传递大量的参数,
可以使用ThreadLocal模式来传递分页参数(包括:offset和pagesize)。
- 定义: 参考SystemContext.java
- 往ThreadLocal中赋值:参考PagerFilter.java
- 从ThreadLocal中获取分页参数:参考AbstractManager.java
package com.xwj.oa.pageSearch;
import java.util.List;
import org.hibernate.Query;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import com.xwj.oa.utils.SystemException;
public class AbstractManager extends HibernateDaoSupport {
public pagerModel searchPaginated (String hql){
return searchPaginated ( hql,null,SystemContext.getOffset(),SystemContext.getPagesize());
}
public pagerModel searchPaginated (String hql,Object param){
return searchPaginated ( hql,new Object[]{param},SystemContext.getOffset(),SystemContext.getPagesize());
}
public pagerModel searchPaginated (String hql,int offset,int pagesize){
return searchPaginated ( hql,null,offset,pagesize);
}
/**
*
* @param hql
* @param params
* @param offset
* @param pagesize
* @return
*/
public pagerModel searchPaginated (String hql,Object[] params,int offset,int pagesize){
String countHql = this.getCountQuery(hql);
Query query = this.getSession().createQuery(countHql);
if(params != null && params.length > 0){
for(int i=0; i<params.length; i++){
query.setParameter(i, params[i]);
}
}
int total = ((Long)query.uniqueResult()).intValue();
query = this.getSession().createQuery(hql);
if(params != null && params.length > 0){
for(int i=0; i<params.length; i++){
query.setParameter(i, params[i]);
}
}
query.setFirstResult(offset);
query.setMaxResults(pagesize);
List datas = query.list();
pagerModel pm = new pagerModel();
pm.setDatas(datas);
pm.setTotal(total);
return pm;
}
private String getCountQuery(String hql){
int index = hql.indexOf("from");
if(index != -1){
String countQuery = "select count(*) "+" "+hql.substring(index);
return countQuery;
}
throw new SystemException("无效的HQL查询");
}
}
package com.xwj.oa.pageSearch;
public class SystemContext {
private static ThreadLocal offset = new ThreadLocal();
private static ThreadLocal pagesize = new ThreadLocal();
public static int getOffset(){
Integer os = (Integer)(offset.get());
if(os == null){
return 0;
}
return os.intValue();
}
public static void setOffset(int offsetValue){
offset.set(new Integer(offsetValue));
}
public static void removeOffset(){
offset.remove();
}
public static int getPagesize(){
Integer ps =(Integer) pagesize.get();
if(ps == null){
return Integer.MAX_VALUE;
}
return ps.intValue();
}
public static void setPagesize(int pagesizeValue){
pagesize.set(new Integer(pagesizeValue));
}
public static void removePagesize(){
pagesize.remove();
}
}
package com.xwj.oa.pageSearch;
import java.util.List;
public class pagerModel {
/**
* 总记录数
*/
private int total;
/**
* 当前的结果集
*/
private List datas;
public int getTotal() {
return total;
}
public void setTotal(int total) {
this.total = total;
}
public List getDatas() {
return datas;
}
public void setDatas(List datas) {
this.datas = datas;
}
}
package com.xwj.oa.pageSearch;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
public class PagerFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest httpRequest = (HttpServletRequest)request;
SystemContext.setOffset(this.getOffset(httpRequest));
SystemContext.setPagesize(this.getPagesize(httpRequest));
try{
chain.doFilter(request, response);
}finally{
SystemContext.removeOffset();
SystemContext.removePagesize();
}
}
private int getOffset(HttpServletRequest httpRequest){
int offset = 0 ;
try{
offset=Integer.parseInt(httpRequest.getParameter("pager.offset"));
}catch(NumberFormatException ignore){
}
return offset;
}
private int getPagesize(HttpServletRequest httpRequest){
return 10;
}
public void init(FilterConfig arg0) throws ServletException {
}
}
上面写了一个fileter,因此要在web-xml中作相应的配置
<!-- pagerFileter -->
<filter>
<filter-name>PagerFilter</filter-name>
<filter-class>com.xwj.oa.pageSearch.PagerFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>PagerFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
public class OrgManagerImpl extends AbstractManager implements OrgManager {
public PagerModel findOrgs(int parentId) {
//如果parentId=0,则查找顶级机构列表
if(parentId == 0){
return searchPaginated("from Orgnization o where o.parent is null");
}
return searchPaginated("from Orgnization o where o.parent.id = ?", parentId);
}
}
public class OrgAction extends DispatchAction {
private OrgManager orgManager;
/**
* 打开机构管理主界面
*/
@Override
protected ActionForward unspecified(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {
OrgActionForm oaf = (OrgActionForm)form;
request.setAttribute("pm",
orgManager.findOrgs(oaf.getParentId())
);
}
}
<pg:pager url="org.do" items="${pm.total }" maxPageItems="10" export="currentPageNumber=pageNumber">
<pg:param name="parentId" />
<pg:first>
<a href="${pageUrl}">首页</a>
</pg:first>
<pg:prev>
<a href="${pageUrl }">前页</a>
</pg:prev>
<pg:pages>
<c:choose>
<c:when test="${currentPageNumber eq pageNumber }">
<font color="red">${pageNumber }</font>
</c:when>
<c:otherwise>
<a href="${pageUrl }">${pageNumber }</a>
</c:otherwise>
</c:choose>
</pg:pages>
<pg:next>
<a href="${pageUrl }">后页</a>
</pg:next>
<pg:last>
<a href="${pageUrl }">尾页</a>
</pg:last>
</pg:pager>