package com.soft.mcz;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;public class Wel extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
Connection con=null;
Statement st=null;
ResultSet rs=null;
PreparedStatement pst=null;
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
con =DriverManager.getConnection("jdbc:mysql://localhost/database1","root","jacob");
st=con.createStatement();
res.setContentType("text/html;charset=gb2312");
PrintWriter pw = res.getWriter();
String nn=req.getParameter("username");
HttpSession hs=req.getSession(true);
;
String name=(String)(hs.getAttribute("name"));
pw.println(name+"欢迎您登录本系统!!!</br>");
pw.println("<image src=images/im.png>");
int pageSize=3 ;
int pageCount=0;
int pageNow=1;
int countSize=0;
String sql2="select count(*) from up";
rs=st.executeQuery(sql2);
if(rs.next()){
countSize=rs.getInt(1);
}
if(countSize%pageSize==0){
pageCount=countSize/pageSize;
}
else{
pageCount=countSize/pageSize+1;
}
pw.println(countSize);
pw.println("<table border=3>");
pw.println("<tr>");
pw.println("<th>姓名</th>");
pw.println("<th>密码</th>");
pw.println("</tr>");
// String sql="select * from up order by username asc LIMIT ?,?";
//(pageNow-1)*pageSize+","+pageSize;
pst=con.prepareStatement("select * from up order by username asc LIMIT ?,?");
pst.setInt(1,(pageNow-1)*pageSize);
pst.setInt(2,pageSize);
rs=pst.executeQuery();
int i= rs.getRow();
pw.println(i);
if(rs.next()){
while(rs.next()){
// pw.println("测试点2");
pw.println("<tr>");
pw.println("<td>"+rs.getString(1)+"</td>");
pw.println("<td>"+rs.getString(2)+"</td>");
pw.println("</tr>");
}
}else{
pw.println("buchenggong ");
}
pw.println("</table>");
}catch(Exception e){
e.getStackTrace();
}
finally{
try{
rs.close();
st.close();
con.close();
}
catch(Exception ee){
}
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}本来我的意想是每页显示3条记录,但是怎么调试都只有两条
用的数据库是mysql
开发工具是JCreateor
谢谢各位大侠的请教姓名 密码
test2 test2
test3 test3
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;public class Wel extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
Connection con=null;
Statement st=null;
ResultSet rs=null;
PreparedStatement pst=null;
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
con =DriverManager.getConnection("jdbc:mysql://localhost/database1","root","jacob");
st=con.createStatement();
res.setContentType("text/html;charset=gb2312");
PrintWriter pw = res.getWriter();
String nn=req.getParameter("username");
HttpSession hs=req.getSession(true);
;
String name=(String)(hs.getAttribute("name"));
pw.println(name+"欢迎您登录本系统!!!</br>");
pw.println("<image src=images/im.png>");
int pageSize=3 ;
int pageCount=0;
int pageNow=1;
int countSize=0;
String sql2="select count(*) from up";
rs=st.executeQuery(sql2);
if(rs.next()){
countSize=rs.getInt(1);
}
if(countSize%pageSize==0){
pageCount=countSize/pageSize;
}
else{
pageCount=countSize/pageSize+1;
}
pw.println(countSize);
pw.println("<table border=3>");
pw.println("<tr>");
pw.println("<th>姓名</th>");
pw.println("<th>密码</th>");
pw.println("</tr>");
// String sql="select * from up order by username asc LIMIT ?,?";
//(pageNow-1)*pageSize+","+pageSize;
pst=con.prepareStatement("select * from up order by username asc LIMIT ?,?");
pst.setInt(1,(pageNow-1)*pageSize);
pst.setInt(2,pageSize);
rs=pst.executeQuery();
int i= rs.getRow();
pw.println(i);
if(rs.next()){
while(rs.next()){
// pw.println("测试点2");
pw.println("<tr>");
pw.println("<td>"+rs.getString(1)+"</td>");
pw.println("<td>"+rs.getString(2)+"</td>");
pw.println("</tr>");
}
}else{
pw.println("buchenggong ");
}
pw.println("</table>");
}catch(Exception e){
e.getStackTrace();
}
finally{
try{
rs.close();
st.close();
con.close();
}
catch(Exception ee){
}
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}本来我的意想是每页显示3条记录,但是怎么调试都只有两条
用的数据库是mysql
开发工具是JCreateor
谢谢各位大侠的请教姓名 密码
test2 test2
test3 test3
解决方案 »
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ResultSet没有hasNext()这个方法,行不通直接去掉if(rs.next)测试通过
public void first() {
currentPage = 1;
startRow = 0;
}
//转到上一页
public void previous() {
if (currentPage == 1) {
currentPage = 1;
startRow = (currentPage - 1) * pageSize;
}else{
currentPage--;
startRow = (currentPage - 1) * pageSize;}
}
//转到下一页
public void next() {
if (currentPage < totalPages) {
currentPage++;
startRow = (currentPage - 1) * pageSize;
}else{
currentPage = currentPage + 1;
currentPage = currentPage - 1;
startRow = (currentPage - 1) * pageSize;
}}
//转到尾页
public void last() {
currentPage = totalPages;
startRow = (currentPage - 1) * pageSize;
}
//设置当前页
public void refresh(int _currentPage) {
currentPage = _currentPage;
if (currentPage > totalPages) {
last();
}
}
--------------dao里的两个查所有值的方法和分页查询方法-------------------------
public List findAll() {
log.debug("finding all Demo instances");
try {
String queryString = "from MyDemo";
List list = getHibernateTemplate().find(queryString);
return list;
} catch (RuntimeException re) {
log.error("find all failed", re);
throw re;
}
}
public List findByPage(int startRow,int pageSize){
log.debug("find alldemo");
Session session = this.getSession() ;
try {
Query query = session.createQuery("from MyDemo");
query.setFirstResult(startRow);
query.setMaxResults(pageSize);
return query.list();
} catch (RuntimeException e) {
log.error("findall failed",e);
throw e;
}
}
--------------------------控制器里的方法-------------------------------
public String findall(HttpServletRequest request,
HttpServletResponse response,ModelMap model){List list = demo1Service.getall();
int totalRows = list.size();
PageBean pageBean = PagerHelper.getPager(request,totalRows);
List mylist = demo1Service.findByPage(pageBean.getStartRow(),pageBean.getPageSize()); request.setAttribute("demolist", mylist);
request.setAttribute("pageBean", pageBean);
return "showlist";
}
看哈我这个
你执行过这个判断,这个指针就向下走了一步
比如说,原来指针是指向0,你做出这个判断,执行了rs.next(),现在这个对象的指针就指向1了,所以你第一个数据取不出来