jsp+servlet+javabean （MVC）分页

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Servlet JSP MVC Java SQL

最近遇到了分页的问题，以前说真的没仔细研究过了，这几天仔细高了一下，基本原理高清楚了，首先是我的页面代码如下：

<%@ page language="java" import="java.util.*,java.sql.*"
 pageEncoding="gb2312"%>
 <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
 <head>
 </head>
 <body>
<form action="#">
   <c:forEach items="${news1}" var="news2" varStatus="status">
        <tr><td>${news2.newsTitle}</td>
           </tr>
  </c:forEach>
       <c:if test="${showpage>1}">
              <a href="pageservlet?topage=<%=1%>">首页</a>
              <a href="pageservlet?topage=${showpage-1}">上一页</a>
              </c:if>
               <c:if test="${showpage<pagecount}">
              <a href="pageservlet?topage=${showpage+1}">下一页</a>
              <a href="pageservlet?topage=${pagecount}">最后一页</a>
              </c:if>
              第${showpage}页
              一共${pagecount}页
 </form> <br>
 </body>
</html>

servlet代码如下：

package org.servlet;

import java.util.ArrayList;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.util.ContactBean;
import org.util.PageBean;

public class PageServlet extends javax.servlet.http.HttpServlet {

 public void doGet(HttpServletRequest

 request, HttpServletResponse response)
   throws javax.servlet.ServletException, java.io.IOException {
  response.setContentType("text/html");
  try {
   PageBean pagebean = new PageBean();
   ContactBean contact = new ContactBean();
   int pagecount = pagebean.countPage();//获取总共的页数
   String topage = request.getParameter("topage");//获取当前的页码
   if (Integer.parseInt(topage) > pagecount) {  //判断当前的页码是否越界,如果是的话就进行处理
    topage =String.valueOf(pagecount);
   } else if (Integer.parseInt(topage) <= 0) {
    topage = "1";
   }
   ArrayList news = contact.getData(topage, pagecount);
   request.getSession().setAttribute("pagecount", pagecount);
   request.getSession().setAttribute("showpage", topage);//将当前的页码返回给页面,这样进行计算
   request.getSession().setAttribute("news1", news);
   response.sendRedirect("test1.jsp");
  } catch (Exception e) {
   e.printStackTrace();
  }

 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)

 throws javax.servlet.ServletException, java.io.IOException {
  doGet(request, response);
 }
}

javabean代码如下

package org.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Vector;

import org.bean.NewsBean;

public class ContactBean {
 private Connection conn;
 public Connection getConnection() {
  try {
   Class.forName("com.mysql.jdbc.Driver");
   conn = DriverManager
     .getConnection(
       "jdbc:mysql://localhost/test?useUnicode=true&amp;characterEncoding=gbk",
       "root", "123456");
  } catch (SQLException ex) {
   System.out.println(ex.getMessage() + "路径错误");
  } catch (ClassNotFoundException ex) {
   System.out.println(ex.getMessage() + "驱动错误");
  }
  return conn;
 }

 /** *返回要查询的记录数 */
 public int getAvailableCount() throws Exception {
  int ret = 0;
  String strSql = "select count(*) from news";
  Connection conn = this.getConnection();
  Statement stmt = conn.createStatement();
  ResultSet rset = stmt.executeQuery(strSql);
  while (rset.next()) {
   ret = rset.getInt(1);
  }
  return ret;
 }
    /*获取查寻的记录数*/
 public ArrayList getData(String topage, int pagecount)
   throws NumberFormatException, SQLException {
  String sql = "select * from news";
  Statement state = null;
  ResultSet rs = null;
  int pagesize = 3;
  int showpage = 1;
  ArrayList list = new ArrayList();
  int j = 0;
  try {
   Connection conn = this.getConnection();
   state = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
     ResultSet.CONCUR_READ_ONLY);
   rs = state.executeQuery(sql);
  } catch (Exception e) {
   System.out.println("exception");
  }
  if (!rs.next()) {
   System.out.println("no records!");
  } else {
   rs.last();
   if (topage != null) {
    showpage = Integer.parseInt(topage);
    if (showpage > pagecount) {
     showpage = pagecount;
    } else if (showpage <= 0) {
     showpage = 1;
    }
   }
   rs.absolute((showpage - 1) * pagesize + 1);
   for (int i = 1; i <= pagesize; i++) {
    NewsBean news = new NewsBean();
    news.setNewsContent(rs.getString(2));
    news.setNewsTitle(rs.getString(3));
    list.add(j, news);
    ++j;
    if (!rs.next())
     break;
   }

  }
  return list;
 }

}

package org.util;


public class PageBean {
 public int maxPage; // 一共有多少页
 public int maxRowCount; // 一共有多少行
 public int pagesize = 3; // 每页多少行
 public PageBean() {
 }

 public int countPage() throws Exception {
 int maxRowCount=this.MaxCount();
  if (maxRowCount % this.pagesize == 0) {
   maxPage = maxRowCount / this.pagesize;
  } else {
   maxPage =maxRowCount/ this.pagesize + 1;
  }
  return maxPage;
 }


 public int MaxCount() throws Exception {
  ContactBean contact=new ContactBean();
  this.maxRowCount = contact.getAvailableCount(); // 得到总行数
        return maxRowCount;
 }

}

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工厂方法(factory method) | mysql中文问题

2010-06-27 20:30
浏览 3181
评论(1)
分类:企业架构
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1 楼 aqxiebin 2010-09-06

为什么mysql不是有limin吗？为什么还要这么麻烦。。奇怪。。

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