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1. 首先是创建分页所需要的通用的javabean类,其封装了分页显示页面所需要的5项数据(见下面代码注释)。我这里命名为PageBean.java,其代码如下:
import java.io.Serializable;
import java.util.List;
@SuppressWarnings("serial")
public class PageBean<E> implements Serializable{
private List<E> list; // 某对象(比如说商城商品)当前页的数据
private Integer currPage; // 当前所在的页数,如第1页,第2页
private Integer pageSize; // 每页所包含的商品的数量
@SuppressWarnings("unused")
private Integer totalPage; // 总页数
private Integer totalCount; // 总商品数
public List<E> getList() {
return list;
}
public void setList(List<E> list) {
this.list = list;
}
public Integer getCurrPage() {
return currPage;
}
public void setCurrPage(Integer currPage) {
this.currPage = currPage;
}
public Integer getPageSize() {
return pageSize;
}
public void setPageSize(Integer pageSize) {
this.pageSize = pageSize;
}
public Integer getTotalPage() {
return (int) Math.ceil(totalCount * 1.0 / pageSize);
}
public Integer getTotalCount() {
return totalCount;
}
public void setTotalCount(Integer totalCount) {
this.totalCount = totalCount;
}
public PageBean() {
super();
}
public PageBean(List<E> list, Integer currPage, Integer pageSize, Integer totalCount) {
super();
this.list = list;
this.currPage = currPage;
this.pageSize = pageSize;
this.totalCount = totalCount;
}
}
2. 控制层Servlet类PageServlet.java代码
public class PageServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
//req.setCharacterEncoding("utf-8");
//res.setContentType("text/html;charset=utf-8");
String currPage = req.getParameter("currPage");
// 当前页变量
Integer iCurrPage = null;
if (currPage != null) {
iCurrPage = Integer.parseInt(currPage);
} else {
iCurrPage = 1; // 没有指定显示哪页时,默认显示第1页
}
String category = req.getParameter("category"); // 根据商品类别查询,如果为null则查询全部书籍
ProductService bookService = new ProductService();
PageBean<Product> pb = bookService.findPageBean(iCurrPage, category);
// 将封装好的pb转发到显示页面:"product_list.jsp"
req.getSession().setAttribute("pb", pb);
res.sendRedirect(req.getContextPath() + "/product_list.jsp");
}
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
doGet(req, res);
}
}
3. service层封装此PageBean的代码
public class ProductService {
public PageBean<Product> findPageBean(Integer iCurrPage, String category) {
// 每页显示4本书
int pageSize = 4;
// 创建一个新的PageBean对象pb
PageBean<Product> pb = new PageBean<Product>();
// 封装当前页数到pb对象
pb.setCurrPage(iCurrPage);
// 封装每页显示商品数到pb对象
pb.setPageSize(pageSize);
ProductDao productDao = new ProductDao();
// totalCount: 数据库中商品的总数
Integer totalCount = null;
List<Product> currPageBookList = null;
try {
totalCount = productDao.findTotalCount();
currPageBookList = productDao.findBooksByPage(iCurrPage, pageSize, category);
} catch (SQLException e) {
e.printStackTrace();
}
// 封装商品总数数据到pb
pb.setTotalCount(totalCount);
// 封装当前页商品List列表数据到pb
pb.setList(currPageBookList);
// 返回此pb给Servlet
return pb;
}
}
4. Dao层去数据库查询相PageBean所需要的数据
public class ProductDao {
public Integer findTotalCount() throws SQLException {
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql = "select count(*) from product";
return ((Long)qr.query(sql, new ScalarHandler())).intValue();
}
public List<Product> findBooksByPage(Integer iCurrPage, int pageSize, String category) throws SQLException {
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql = null;
if (category != null) { // 查询指定类别的商品
sql = "select * from product where category=? limit ?,?";
return qr.query(sql, new BeanListHandler<Product>(Product.class), category, (iCurrPage-1)*pageSize, pageSize);
} else { // 查询所有类别的商品
sql = "select * from product limit ?,?";
return qr.query(sql, new BeanListHandler<Product>(Product.class), (iCurrPage-1)*pageSize, pageSize);
}
}
}
5. 最后在前端product_list.jsp页面进行分页显示
<table cellspacing="0" class="booklist">
<tr>
<c:forEach items="${pb.list}" var="book">
<td>
<div class="divbookpic">
<p>
<a href="product_info.jsp"><img src="${pageContext.request.contextPath}/${book.imgurl}" width="115"
height="129" border="0" alt="${book.name}"/>
</a>
</p>
</div>
<div class="divlisttitle">
<a href="product_info.jsp">书名:${book.name}<br />售价:${book.price}</a>
</div>
</td>
</c:forEach>
</tr>
</table>
<!-- 分页导航 -->
<div class="pagination">
<ul>
<c:if test="${pb.currPage==1}">
<li class="disablepage"><a href="javascript:void(0);"><<上一页</a></li>
</c:if>
<c:if test="${pb.currPage!=1}">
<li><a href="${pageContext.request.contextPath}/pageServlet?currPage=${pb.currPage-1}"><<上一页</a></li>
</c:if>
<!-- <li>第${pb.currPage}页/共${pb.totalPage}页</li> -->
<c:forEach begin="1" end="${pb.totalPage}" var="v">
<li><a href="product_info.jsp">${v}</a></li>
</c:forEach>
<c:if test="${pb.currPage==pb.totalPage}">
<li class="disablepage"><a href="javascript:void(0);">下一页>></a></li>
</c:if>
<c:if test="${pb.currPage!=pb.totalPage}">
<li ><a href="${pageContext.request.contextPath}/pageServlet?currPage=${pb.currPage+1}">下一页>></a></li>
</c:if>
</ul>
</div>
原文出处：https://segmentfault.com/a/1190000012495633
程序猿的技术大观园：www.javathinker.net
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Java技术网站 → 『 Java开发技术 』 → 『 Java Web开发技术专题 』 → JavaWeb分页的简单实现
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