jsp+servlet+javabean （MVC）分页
2008-12-11 21:38
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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，上次我发了一个jsp的分页程序了，其实那个还有很多地方完善，这两天总结了一下，用MVC摸式改进了一下，还是强调一点我一直都觉的JSP不要在页面写代码，因为影响分工了，所以我一直在编程都努力的在做了，但是这些代码我只是完成了功能，还有代码优化的地方，我没去做，这个批评一下自己了，不过因为最近真的好多事了，说真的由于我的电脑硬盘坏了，好多东西我都从头来学，真的好郁闷了，其实这些我以前都做出来了，但是电脑挂了，没办法了，从头来啊！不乱砍了，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&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;
}
}
其实这两个JAVABEAN可以写成一个了，并且很多代码可以提出来，做成一个复用性强的代码了，这里我结合我这几天上网查资料的感受，那些分页多半是只能作者能用了，读者就用不了。所以我这里写了全部代码了，也不知道别人看不看的懂了！
<%@ 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&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;
}
}
其实这两个JAVABEAN可以写成一个了，并且很多代码可以提出来，做成一个复用性强的代码了，这里我结合我这几天上网查资料的感受，那些分页多半是只能作者能用了，读者就用不了。所以我这里写了全部代码了，也不知道别人看不看的懂了！
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