分页的第三种方式

优点：

1.通用性更好，给为页码写一个类，更符合面向对象的思维

2.代码十分简洁

缺点：

1.不能及使获取数据库中数据的变化

封装进Dao对象，通过一个方法返回一个map，map里有一个页码对象，还有一个页面数据对象

public class FenyeService {

private HibernateDao dao;

public FenyeService() {

dao = new HibernateDao();

}

public Map getPageData(int page) {

List products = null;

try {

products = dao.getProducts(page);

} catch (Exception ex) {

ex.printStackTrace();

}

PageArgs pageArgs = dao.getPageArgs();

pageArgs.setPageNum(page);

Map model = new HashMap();

model.put("list", products);

model.put("pageArgs", pageArgs);

return model;

}

}

//页码类，省略了get/set方法

public class PageArgs {

private int pageNum;

private int pageSize;

private long maxPage;

private int prePage;

private int nextPage;

public void setPageNum(int pageNum) {

this.pageNum = pageNum;

prePage=pageNum-1<=1?1:pageNum-1;

nextPage=(int) (pageNum + 1 >= maxPage ? maxPage : pageNum + 1);

}

}

Servlet中封装了service对象。

@WebServlet("/PageServlet")

public class PageServlet extends HttpServlet {

private FenyeService fenyeService;

public PageServlet() {

fenyeService = new FenyeService();

}

//处理get或post请求

protected void processRequest(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

int page = ServletRequestUtils.getIntParameter(request, "page", 1);

Map model = fenyeService.getPageData(page);

request.setAttribute("model", model);

request.getRequestDispatcher("page.jsp").forward(request, response);

}

}

一个工具类

ublic class ServletRequestUtils {

public static double getDoubleParameter(HttpServletRequest request, String param, double defVal) {

String val = request.getParameter(param);

try {

double num = Double.parseDouble(val);

return num;

} catch (NumberFormatException Exception) {

return defVal;

}

}

public static int getIntParameter(HttpServletRequest request, String param, int defVal) {

String val = request.getParameter(param);

try {

int num = Integer.parseInt(val);

return num;

} catch (NumberFormatException Exception) {

return defVal;

}

}

}

JSP页面

<!--页面数据显示-->

<c:forEach items="${model['list']}" var="rec">

<tr>

<td height="27">${rec.id}</td>

<td>${rec.productName}</td>

<td>${rec.price}</td>

<td>${rec.unit}</td>

<td>${rec.num}</td>

<td>${rec.inDate}</td>

<td>${rec.baozhiTime}</td>

</tr>

</c:forEach>

<!--页码显示-->

<a href="PageServlet?page=1">第一页</a>

<a href="PageServlet?page=${model['pageArgs'].prePage}">上一页</a>

&nbsp;${model['pageArgs'].pageNum}/${model['pageArgs'].maxPage}&nbsp;

<a href="PageServlet?page=${model['pageArgs'].nextPage}">下一页</a> <a

href="PageServlet?page=${model['pageArgs'].maxPage}">尾页</a>