JSP实现从mysql读取数据并实现分页功能

来源：互联网发布：淘宝中国历代名家画集编辑：程序博客网时间：2024/05/16 09:08

最近学习JSP。结合之前的jdbc写了一个从数据库读取数据并分页在页面中显示的程序。

1、login界面

<html><head><meta http-equiv="content-type",content="text/html;charset=gb2312"/><title>Welcome to the TEST!</title></head><body><center><h1>Please check in!</h1><hr><form action="check.jsp" method="post"><table border="2"><tr><td colspan="2"><center>Users Login</center></td></tr><tr><td>User ID:</td><td><input type="text" name="id"></td></tr><tr><td>User Name:</td><td><input type="text" name="name"></td></tr><tr><td>User Password:</td><td><input type="password" name="password"></td></tr><tr><td><input type="submit" value="submit"></td><td><input type="reset" value="reset"></td></tr></table></form></center></body></html>

2、在check.jsp页面中进行判断，是否由此用户。

<%@page contentType="text/html" pageEncoding="gb2312" %><%@page import="java.sql.*" %><html><head><title>check</title></head><body><%!public static final String DBDRIVER="org.gjt.mm.mysql.Driver";public static final String DBURL="jdbc:mysql://localhost:3306/client";public static final String DBUSER = "root";public static final String DBPASSWORD = "pass";%><%Connection conn = null;String sql = null;PreparedStatement pstmt = null;ResultSet rs = null;Boolean flag = false;String name_get = request.getParameter("name");try{Class.forName(DBDRIVER);conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);sql = "select name from client where id=? AND password=?";pstmt = conn.prepareStatement(sql);pstmt.setString(1,request.getParameter("id"));pstmt.setString(2,request.getParameter("password"));rs =pstmt.executeQuery();if(rs.next()){name_get = rs.getString(1);flag=true;}}catch(Exception e){}finally{try{rs.close();pstmt.close();conn.close();}catch(Exception e){}}%><%if(flag){%><jsp:forward page="success.jsp">  <jsp:param name="get" value="<%=name_get%>"/></jsp:forward><%}else{%><jsp:forward page="failure.jsp">               <jsp:param name="get" value="<%=name_get%>"/></jsp:forward><%}%></body></html>

3、登陆失败，跳转到failure.jsp页面

<%@page contentType="text/html" pageEncoding="gb2312" %><html><head><title>Login failed!</title></head><body><%String name = request.getParameter("get");%><center><h1>Login failed!</h1><br/><h2>Name <font color="red"><%=name%></font> doesn't exist!</h2> <h2>Please Click <a href="login.html">here</a> to login again!</h2></center></body></html>

4、登陆成功，跳转到success.jsp页面。在此页面中实现分页功能

<%@page contentType="text/html" pageEncoding="gb2312" %><%@page import="java.sql.*"%><html><head><title>Login successful!</title></head><body><%String name = request.getParameter("get");%><center><h1>Hello ! Dear <font color="blue"><%=name%></font>~! </h1><br/><%!public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";public static final String DBURL = "jdbc:mysql://localhost:3306/client";public static final String DBUSER = "root";public static final String DBPASS = "pass";public static final int PAGEITEMS = 5;%><%Connection conn = null;PreparedStatement pstmt = null;ResultSet rs = null;String sql = null;String empno = null;String ename = null;String job = null;double sal = 0;int pagenum = 0;String currentpage_tmp = null;int currentpage = 1;String flag_tmp = null;int flag = 0;%><hr><caption><h3>empire list</h3></caption><table border = "2" width="400"><tr><td>empno</td><td>ename</td><td>job</td><td>sal</td></tr><%Class.forName(DBDRIVER);conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);pstmt = conn.prepareStatement("select * from data",ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);rs = pstmt.executeQuery();rs.last();pagenum = rs.getRow()/PAGEITEMS==0?(rs.getRow()/PAGEITEMS):(rs.getRow()/PAGEITEMS+1);currentpage_tmp = request.getParameter("currentpage");flag_tmp = request.getParameter("flag");if(currentpage_tmp == null){currentpage_tmp = "1";}if(flag_tmp == null){flag_tmp = "0";}currentpage = Integer.parseInt(currentpage_tmp);flag = Integer.parseInt(flag_tmp);if(flag==2){currentpage++;}else if(flag==1){currentpage--;}if(currentpage == 0){currentpage = 1;}else if(currentpage == pagenum+1){currentpage = pagenum;}sql = "select empno,ename,job,sal from data limit "+(currentpage-1)*5+","+PAGEITEMS;pstmt = conn.prepareStatement(sql,ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);rs = pstmt.executeQuery();while(rs.next()){empno = rs.getString(1);ename = rs.getString(2);job = rs.getString(3);sal = rs.getDouble(4);%><tr><td><%=empno%></td><td><%=ename%></td><td><%=job%></td><td><%=sal%></td></tr><%}%></table><a href="success.jsp?currentpage=1&flag=0&get=<%=name%>">FP</a>  <a href="success.jsp?currentpage=<%=currentpage%>&flag=1&get=<%=name%>">Back</a> <a href="success.jsp?currentpage=<%=currentpage%>&flag=2&get=<%=name%>">Forw</a> <a href="success.jsp?currentpage=<%=pagenum%>&flag=0&get=<%=name%>">LP</a></center></body></html>

对分页功能的分析：

首先要知道的是，分页功能便是服务器端跳转的实现。在最后的四个超链接中，分别传递了currentpage和flag两个参数。

在此介绍一下超链接传值的语法格式：

为了实现分页，即跳转到本页。currentpage是记录当前页的参数，flag是用来判断到底页码+1还是页码-1的参数。在本页面加载之前利用jsp内置对象进行接收，如此循环。

还有就是，要注意这两个参数在第一次循环运行时的空指针报错。因此要加上null时的if处理语句。

总体来说还是蛮简单的。

0 0