java数据库的分页
package tee;
import java.util.List;
import https://www.360docs.net/doc/4312333520.html,ers.Constants;
public class ss {
private int count = 10;
private int dataCount ;
private List list;
private int pageCount;
private int currentPageIndex;
private int startIndex;
private int endIndex;
public ss(int currentPageIndex,int dataCount ){
this.currentPageIndex = currentPageIndex;
this.dataCount =dataCount;
pageCount = (dataCount +count-1 )/count;
if(pageCount <5){
startIndex = 1 ;
endIndex = pageCount;
}else{
/*startIndex = Constants.getStartNumber();
endIndex = Constants.getStartNumber();
if(currentPageIndex == Constants.getStartNumber())*/
{
startIndex = currentPageIndex-1;
endIndex = currentPageIndex+3;
/*Constants.setStartNumber(Constants.getStartNumber()-1)*/ /*Constants.setEndtNumber(Constants.getEndNumber()-1)*/ }
/*if(currentPageIndex == Constants.getEndNumber())*/
{
startIndex = currentPageIndex-3;
endIndex = currentPageIndex+1;
/*Constants.setStartNumber(Constants.getStartNumber()-1)*/ /*Constants.setEndtNumber(Constants.getEndNumber()-1)*/
}
if (startIndex<1){
startIndex = 1;
endIndex =5;
/*Constants.setStartNumber();*/
/*Constants.setEndNumber();*/
}
if(endIndex>pageCount){
startIndex = pageCount-4;
endIndex = pageCount;
/*Constants.setStartNumber(pageCount-4);*/
/*Constants.setEndNumber(pageCount);*/
}
}
}
}
EL表达式
<%@page language="java"contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
${https://www.360docs.net/doc/4312333520.html,ername};
<%=request.getParameter("username")%>/* 当username为空的时候EL不显示而表达式会显示null */
<%=request.getParameterValues("hobbies")[0]%>
${paramValues.hobbies[0]} /* 返回一个数组当checkbox时候 */
<%-- <%=((User)request.getAttribute("user")).getPwd()%> --%> ${https://www.360docs.net/doc/4312333520.html,er.pwd}
${user.pwd} /* 当不指定范围的时候自动从pageScope开始查找,直到application, */
${header.accept}/* 输出请求头accept的值 */
${headerValues.cookie[0]}
${ cookie.JSESSIONID.value}
/*
*/
${initParam.path}
${pageContext.request} /* 方法输出请求对象 */ ${pageContext.request.remoteAddr} /* 输出127.0.0.1 */ ${19%2}/* %或mod方法是按求模 */
${A?B:C}/* 如果a为true则执行b如果a为false则执行c */ ${requestScore.cust2.custname} 获取数据的方式
/* ${requestScore["cust2"]["custname"]} */
/* 只能使用[] 的情况 */
${paramValues.hobbies[0]}
${requestScope.list[1].custname}
${param["user_name"]}
${param[paramName]}
${param.count+10}
访问次数
<%=application.getAttribute("count") %>
欢迎
<%=session.getAttribute("userName") %>登录
登录成功欢迎您:${https://www.360docs.net/doc/4312333520.html,ername}
您是第${applicationScope.count}位访者
servlet
package com.chinasofti.eec.servlet;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/login")
public class UserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String btn = req.getParameter("btn");
String name = req.getParameter("user");
String pwd = req.getParameter("pwd");
if("???".equals(btn)){
if("admin".equals(name)&&"admin".equals(pwd)){
ServletContext ctxt =
this.getServletContext();
int count = 0;
if(ctxt.getAttribute("count")==null){
count= 0;
}else{
count =
Integer.parseInt(ctxt.getAttribute("count").toString());
}
count++;
ctxt.setAttribute("count", count);
String timeLength =
req.getParameter("date");
int days = 0;
if(timeLength!=null){
days = Integer.parseInt(timeLength);
}
if(days!=0){
Cookie usernamecookie = new
Cookie("username",name);
Cookie userpwd = new
Cookie("userpwd",pwd);
usernamecookie.setMaxAge(days*24*3600);
userpwd.setMaxAge(days*24*36000);
resp.addCookie(usernamecookie);
resp.addCookie(userpwd);
}
req.getSession().setAttribute("userName", name);
resp.sendRedirect("index.jsp");
}
}
}
}
JSTL赋值表达式
<%@page language="java"contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
/*
*
*/
使用jstl表达式
<%-- <%@ taglib uri="https://www.360docs.net/doc/4312333520.html,/jsp/jstl/core" prefix = "c""%> --%>
JSTL练习
package Dao;
import java.sql.Time;
public class User {
public User() {
// TODO Auto-generated constructor stub
}
public User(String string, String string2, String string3, String string4, Time time) {
// TODO Auto-generated constructor stub
}
private String userid;
private String username;
private String userage;
private String userpwd;
private String remark;
private String useraddress;
}
DAO
在UserDao中,定义selectAll方法,查询表user,返回所有记录,封装到集合中返回
package Dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class UserDao {
public List
List
Connection conn = null;
String sql = "select * from User";
PreparedStatement pstmt = null;
ResultSet rs = null;
User user = new User();
try {
pstmt = conn.prepareStatement(sql);
rs = pstmt.executeQuery();
while(rs.next()){
user = new
User(rs.getString(1),rs.getString(2),rs.getString(3),rs.getString (4),rs.getTime(5));
userlist.add(user);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return userlist;
}
}
在UserService类中定义viewAllEmloyees方法
package Dao;
import java.util.List;
public class UserService {
private UserDao dao = new UserDao();
public List
return dao.selectAll();
}
}
创建ViewAllServlet调用UserService返回用户列表并跳转的jsp页面注意跳转路径package Dao;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ViewAllServlet extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub
UserService us = new UserService();
List
req.setAttribute("userlist", list);
req.getRequestDispatcher("admin/viewemployeesold.jsp").forwa rd(req, resp);
}
}
HttpServlet
package servlet;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class html extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub
String btn = req.getParameter("btn");
String name = req.getParameter("user");
String pwd = req.getParameter("pwd");
/*请求行请求方式(GET/POST)请求资源URL*/
req.getMethod();
req.getRequestURI();
req.getProtocol();
/*请求头键值队形式存在 */
req.getHeader("name");
req.getHeaderNames();
/*获取参数数据 get或post*/
req.getParameterNames(); /*所有参数*/
req.getParameterValues("name");/* 多个值的参数*/
req.getParameter("name"); /* 一个值的内容*/
if("登录".equals(btn)){
{
if("admin".equals(name)&&"admin".equals(pwd)){
ServletContext ctxt =
this.getServletContext();
int count = 0;
if(ctxt.getAttribute("count")==null){
count= 0;
}else{
count =
Integer.parseInt(ctxt.getAttribute("count").toString());
}
count++;
ctxt.setAttribute("count", count);
}
}
}
}
}
Info
package servlet;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ServieltInfo extends HttpServlet{
private static final byte[] sa = null;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub
this.doPost(req, resp);
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub
String m = req.getParameter("m");
if("findAllUser".equals(m)){
/*UserService us = new UserServiceImpl();
List
/*int count = us.getUserCountInfo();*/
Map
HashMap
/*mapdata.put("rows", list);
mapdata.put("total", count);*/
if(mapdata!=null){
/*resp.getWriter().print(new
Gson().toJson(mapdata));*/
resp.setStatus(0); /*相应行*/
resp.setHeader("name", "value"); /*相应头*/
/*实体内容*/
resp.getWriter().write("ss"); /*字符内容*/
resp.getOutputStream().write(sa); /*字节内容*/
}
}
}
}
Vo
<%@page language="java"contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
访问次数
<%=application.getAttribute("count") %>
欢迎
<%=session.getAttribute("userName") %>登录