使用的框架是struts2+spring3+hibernate4，需要特别注意两点，其一是保证三层的松耦合，我看到有文章在Service层中向Dao传递HQL语句，其实是不对的；二是，新版hibernate在查询COUNT(*)返回记录数量时，类型改为了Long型，需要做特殊处理。
首先要做一个PageBean对象：
public class PageBean {
//Result List
@SuppressWarnings("rawtypes")
private List list;
//总行数
private Long allRow;
//总页数
private Integer totalPage;
//当前页
private Integer currentPage;
//每页条目数
private Integer pageSize;
//是否为第一页
private Boolean firstPage;
//是否为最后一页
private Boolean lastPage;
//是否有前一页
private Boolean hasPreviousPage;
//是否有后一页
private Boolean hasNextPage;
@SuppressWarnings("rawtypes")
public List getList() {
return list;
}
@SuppressWarnings("rawtypes")
public void setList(List list) {
this.list = list;
}
public Long getAllRow() {
return allRow;
}
public void setAllRow(Long allRow) {
this.allRow = allRow;
}
public Number getTotalPage() {
return totalPage;
}
public Integer getCurrentPage() {
return currentPage;
}
public void setCurrentPage(Integer currentPage) {
this.currentPage = currentPage;
}
public Integer getPageSize() {
return pageSize;
}
public void setPageSize(Integer pageSize) {
this.pageSize = pageSize;
}
public void setTotalPage(Integer totalPage) {
this.totalPage = totalPage;
}
public Boolean getFirstPage() {
return firstPage;
}
public void setFirstPage(Boolean firstPage) {
this.firstPage = firstPage;
}
public Boolean getLastPage() {
return lastPage;
}
public void setLastPage(Boolean lastPage) {
this.lastPage = lastPage;
}
public Boolean getHasPreviousPage() {
return hasPreviousPage;
}
public void setHasPreviousPage(Boolean hasPreviousPage) {
this.hasPreviousPage = hasPreviousPage;
}
public Boolean getHasNextPage() {
return hasNextPage;
}
public void setHasNextPage(Boolean hasNextPage) {
this.hasNextPage = hasNextPage;
}
/**
* 初始化结果页面信息
*/
public void init(){
this.firstPage = isFirstPage();
this.lastPage = isLastPage();
this.hasPreviousPage = isHasPreviousPage();
this.totalPage = countTotalPage(pageSize, allRow);
this.hasNextPage = isHasNextPage();
}
private boolean isFirstPage() {
return currentPage == 1;
}
private boolean isLastPage() {
return currentPage == totalPage;
}
private boolean isHasPreviousPage() {
return currentPage != 1;
}
private boolean isHasNextPage() {
return currentPage != totalPage;
}
/**
* 计算总页数
* @param pageSize 每页记录数
* @param allRow 总记录数
* @return 总页数
*/
private Integer countTotalPage(Integer pageSize,Long allRow){
Integer row = allRow.intValue();
Integer totalPage = row.intValue() % pageSize == 0 ? row/pageSize : row/pageSize+1;
return totalPage;
}
/**
* 计算当前页起始记录
* @param pageSize 每页记录数
* @param currentPage 当前第几页
* @return
*/
public Integer countOffset(Integer pageSize,Integer currentPage){
Integer offset = pageSize*(currentPage-1);
return offset;
}
}
DAO层添加的两个接口实现如下：
public List<User> getUsersByPage(Integer offSet, Integer length) {
String hql = "FROM com.wang.rhys.model.User";
@SuppressWarnings("unchecked")
List<User> list = (ArrayList<User>)this.getObjects(hql, offSet, length);
return list;
}
public Long getTotalUserNumber(Integer groupId) {
String hql = "SELECT COUNT(*) FROM com.wang.rhys.model.User ";
if(groupId!=0)
hql+="WHERE group.group_id="+groupId;
Long totalRows = (Long)this.getObject(hql);
return totalRows;
}
Service层的接口实现：
public PageBean getUsersByPage(Integer currentPage, Integer pageSize) {
PageBean pageBean = new PageBean();
//Set Parameters
Long totalRows = userDao.getTotalUserNumber(0);
pageBean.setAllRow(totalRows);
pageBean.setCurrentPage(currentPage);
pageBean.setPageSize(pageSize);
//Initialize PageBean
pageBean.init();
//Get the splitted userList
List<User> userList = userDao.getUsersByPage(pageBean.countOffset(pageSize, currentPage),pageSize);
pageBean.setList(userList);
return pageBean;
}
Struts Action实现：
public String execute() throws Exception {
//从session获取用户工号，如果不存在或处于非激活状态，返回登录页面
String user_num = ActionContext.getContext().getSession().get("user_num").toString();
if(!userService.isActive(user_num))
return LOGIN;
setPageBean(userService.getUsersByPage(currentPage, pageSize));
return SUCCESS;
}
页面调用：
<table border="1" width="700px">
<!-- table head -->
<tr>
<td style="width:100px">工号</td>
<td style="width:100px">姓名</td>
<td style="width:150px">组件</td>
<td style="width:50px">性别</td>
<td style="width:100px">职位</td>
<td style="width:200px">备注</td>
</tr>
<s:iterator value="#request.pageBean.list" status="st">
<s:if test="#st.odd==true">
<tr style="background-color: #cccccc">
</s:if>
<s:else>
<tr>
</s:else>
<td><s:property value="user_number"/></td>
<td><s:property value="user_chinese_name"/></td>
<td><s:property value="group.group_chinese_name"/></td>
<td><s:property value="sex"/></td>
<td></td>
<td>
<s:url id="modify_user" value="ShowModifyUserForm.action">
<s:param name="user_id" value="user_id">
</s:param>
</s:url>
<s:a href="%{modify_user}">修改</s:a>
</td>
</tr><p/>
</s:iterator>
<tr>
<td style="width:100px">
<s:if test="#request.pageBean.hasPreviousPage">
<s:url id="getUsers_first" value="GetUsers.action">
<s:param name="currentPage" value="1"></s:param>
</s:url>
<s:a href="%{getUsers_first}">首页</s:a>
</s:if>
<s:else>
首页
</s:else>
</td>
<td style="width:100px">
<s:if test="#request.pageBean.hasPreviousPage">
<s:url id="getUsers_previous" value="GetUsers.action">
<s:param name="currentPage" value="#request.pageBean.currentPage-1"></s:param>
</s:url>
<s:a href="%{getUsers_previous}">上页</s:a>
</s:if>
<s:else>
上页
</s:else>
</td>
<td style="width:150px">
<s:if test="#request.pageBean.hasNextPage">
<s:url id="getUsers_next" value="GetUsers.action">
<s:param name="currentPage" value="#request.pageBean.currentPage+1"></s:param>
</s:url>
<s:a href="%{getUsers_next}">下页</s:a>
</s:if>
<s:else>
下页
</s:else>
</td>
<td style="width:50px">
<s:if test="#request.pageBean.hasNextPage">
<s:url id="getUsers_last" value="GetUsers.action">
<s:param name="currentPage" value="#request.pageBean.totalPage"></s:param>
</s:url>
<s:a href="%{getUsers_last}">末页</s:a>
</s:if>
<s:else>
末页
</s:else>
</td>
<td style="width:100px">共<s:property value="pageBean.totalPage"/>页</td>
<td style="width:200px">共<s:property value="pageBean.allRow"/>条记录</td>
</tr>
</table>
时间： 2024-10-01 00:23:23