学习篇--（jsp+servlet+mysql） 登录界面 【前后台交互学习笔记】
经典的样例，自己手打一边，学习一下！
UserBean，代码如下：
package com.szx.jnmc;
public class User {
private String username;
private String userpass;
private int role;
private int lognum;
private String regtime;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getUserpass() {
return userpass;
}
public void setUserpass(String userpass) {
this.userpass = userpass;
}
public int getRole() {
return role;
}
public void setRole(int role) {
this.role = role;
}
public int getLognum() {
return lognum;
}
public void setLognum(int lognum) {
this.lognum = lognum;
}
public String getRegtime() {
return regtime;
}
public void setRegtime(String regtime) {
this.regtime = regtime;
}
}
================================================================================================
对user进行数据的封装。
下面再写一个数据库连接类DBOper 这个类具有连接数据库以及增删改（executeUpdate）查（executeQuery）的功能，以便于AddUserServlet的调用
package com.szx.jnmc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class DBOper {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
//打开连接
public Connection getConn(String server,String dbname,String dbuser,String dbpwd){
String DRIVER = "com.mysql.jdbc.Driver";
String URL = "jdbc:mysql://"+server+":3306/"+dbname+"?user="+dbuser+"&password="+dbpwd+"&useUnicode=true&characterEncoding=utf8";
try{
Class.forName(DRIVER);
conn = DriverManager.getConnection(URL);
}catch(Exception e){
e.printStackTrace();
}
return conn;
}
//关闭连接
public void closeAll(){
try{
if(rs != null){
rs.close();
}
}catch(SQLException e){
e.printStackTrace();
}finally{
try{
if(ps != null){
ps.close();
}
}catch(SQLException e){
e.printStackTrace();
}finally{
try{
if(conn != null){
conn.close();
}
}catch (SQLException e){
e.printStackTrace();
}
}
}
}
//执行sql语句，可以进行查询
public ResultSet executeQuery(String preparedSql,String []param){
try{
ps = conn.prepareStatement(preparedSql);
if(param != null){
for (int i = 0; i < param.length; i++) {
ps.setString(i + 1, param[i]);
}
}
rs = ps.executeQuery();
}catch(SQLException e){
e.printStackTrace();
}
return rs;
}
//执行sql语句，增加，修改，删除
public int executeUpdate(String preparedSql,String[]param){
int num = 0;
try{
ps = conn.prepareStatement(preparedSql);
if(ps != null){
for (int i = 0; i < param.length; i++) {
ps.setString(i + 1, param[i]);
}
}
num = ps.executeUpdate();
}catch(SQLException e){
e.printStackTrace();
}
return num;
}
}
==========================================================================
数据库连接类写完之后，继续写一个UserDao，这个类主要功能是对用户进行增删改查 代码如下：
package com.szx.jnmc;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class UserDao extends DBOper{
//获取用户列表
public List getUser(){
ListuserList = new ArrayList();
User user = new User();
String sql = "SELECT * FROM tb_user";
try{
ResultSet rs = this.executeQuery(sql,null);
while(rs.next()){
user.setUsername(rs.getString("username"));
user.setUserpass(rs.getString("userpass"));
user.setLognum(rs.getInt("lognum"));
user.setRegtime(rs.getString("regtime"));
user.setRole(rs.getInt("role"));
userList.add(user);
}
}catch(SQLException e){
e.printStackTrace();
}finally{
this.closeAll();
}
return userList;
}
//根据用户名获取用户
public User getUserByName(String name){
User user = null;
String sql = "SELECT * FROM tb_user WHERE username = ?";
try{
ResultSet rs = this.executeQuery(sql, new String[]{name});
if(rs.next()){
user = new User();
user.setUsername(rs.getString("username"));
user.setUserpass(rs.getString("userpass"));
user.setRole(rs.getInt("role"));
user.setLognum(rs.getInt("lognum"));
user.setRegtime(rs.getString("regtime"));
}
}catch(SQLException e){
e.printStackTrace();
}finally{
this.closeAll();
}
return user;
}
//修改用户信息
public boolean editUser(User user){
boolean r = false;
String sql = "UPDATE tb_user SET userpass = ?,role = ?,regtime = ?,lognum = ? WHERE username = ?";
try{
int num = this.executeUpdate(sql, new String[]{user.getUserpass(),""+user.getRole(),""+user.getLognum(),user.getRegtime(),user.getUsername()});
if(num > 0){
r = true;
}
}catch(Exception e){
e.printStackTrace();
}finally{
this.closeAll();
}
return r;
}
//添加用户
public boolean addUser(User user){
boolean r = false;
String sql = "INSERT INTO tb_user(username,userpass,role,regtime)VALUES(?,?,?,?) ";
try{
int num = this.executeUpdate(sql,new String[]{user.getUsername(),user.getUserpass(),""+user.getRole(),user.getRegtime()});
if(num > 0){
r = true;
}
}catch(Exception e){
e.printStackTrace();
}finally{
this.closeAll();
}
return r;
}
//删除指定用户
public boolean delUser(String name){
boolean r = false;
String sql = "DELETE FROM tb_user WHERE username = ?";
try{
int num = this.executeUpdate(sql,new String[]{name});
if(num > 0){
r = true;
}
}catch(Exception e){
e.printStackTrace();
}finally{
this.closeAll();
}
return r;
}
}
===============================================================================================
注册部分的jsp，addUser.jsp用来接收用户的输入。抛开各种样式，直接用最原始的样式呈现吧，代码如下：
<%@ page language="java" contentType="text/html; charset=GBK"
pageEncoding="GBK"%>
添加用户页面
===============================================
注意页面的字符编码设置统一为GBK(以GBK为例，如果自己写的话最好用UTF-8）
下面写我们的AddUserServlet，不多说，直接贴代码：
package com.szx.jnmc;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class AddUserServlet
*/
@WebServlet("/AddUserServlet")
public class AddUserServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public AddUserServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request,response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("GBK");
response.setContentType("text/html;charset = GBK");
String username = request.getParameter("username");
String userpass = request.getParameter("userpass");
//String role = request.getParameter("role");
Date curTime = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String regtime = sdf.format(curTime);
PrintWriter out = response.getWriter();
ServletContext ctx = this.getServletContext();
String server = ctx.getInitParameter("server");
String dbname = ctx.getInitParameter("dbname");
String dbuser = ctx.getInitParameter("dbuser");
String dbpwd = ctx.getInitParameter("dbpwd");
User user = new User();
user.setUsername(username);
user.setUserpass(userpass);
user.setRegtime(regtime);
//user.setRole(Integer.parseInt(role));
UserDao dao = new UserDao();
dao.getConn(server, dbname, dbuser, dbpwd);
if(dao.addUser(user)){
out.print("注册成功！");
}
else{
out.print("注册失败！");
}
}
}===============================================================================================
接下来我们写登陆部分，login.jsp代码如下：
<%@ page language="java" contentType="text/html; charset=GBK"
pageEncoding="GBK"%>
登陆页面
================================================================================================
LoginServlet代码如下：
package com.szx.jnmc;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.RequestDispatcher;
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;
import javax.servlet.http.HttpSession;
/**
* Servlet implementation class LoginServlet
*/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public LoginServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request,response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("GBK");
response.setContentType("text/html;charset = GBK");
PrintWriter out = response.getWriter();
String username = request.getParameter("username");
String userpass = request.getParameter("userpass");
ServletContext ctx = request.getServletContext();
String server = ctx.getInitParameter("server");
String dbname = ctx.getInitParameter("dbname");
String dbuser = ctx.getInitParameter("dbuser");
String dbpwd = ctx.getInitParameter("dbpwd");
DBOper db = new DBOper();
db.getConn(server, dbname, dbuser, dbpwd);
String sql = "SELECT username,userpass,role FROM tb_user WHERE username = ? AND userpass = ?";
ResultSet rs = db.executeQuery(sql,new String[]{username,userpass});
try {
if(rs != null && rs.next()){
HttpSession session = request.getSession();
session.setAttribute("username",username);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String logtime = sdf.format(new Date());
session.setAttribute("logtime",logtime);
Cookie cookie = new Cookie("username",username);
cookie.setMaxAge(60*60*24*30);
response.addCookie(cookie);
RequestDispatcher dispatcher = request.getRequestDispatcher("MainServlet");
dispatcher.forward(request,response);
}else{
out.print("登录失败");
out.print("
重新登陆");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void init()throws ServletException {
}
}
==========================================================================================
LoginServlet里的MianServlet用来显示登陆成功的信息，登陆失败则跳转到login.jsp重新登陆，MainServlet的代码如下：
package com.szx.jnmc;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* Servlet implementation class MainServlet
*/
@WebServlet("/MainServlet")
public class MainServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public MainServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request,response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("GBK");
response.setContentType("text/html;charaset = GBK");
PrintWriter out = response.getWriter();
HttpSession session = request.getSession();
String username = (String)session.getAttribute("username");
String logtime = (String)session.getAttribute("logtime");
out.println("登录名:"+username+" 登陆时间:"+logtime);
out.println("欢迎"+username);
}
}
===============================================================================================
到此我们还有最重要的一步，就是在web.xml里配置我们的项目，web.xml代码如下：
20170512
index.html
index.htm
index.jsp
default.html
default.htm
default.jsp
server
localhost
dbname
A20170512
dbuser
root
dbpwd
123456
AddUserServlet
AddUSerServlet
com.szx.jnmc.AddUserServlet
LoginServlet
LoginServlet
com.szx.jnmc.LoginServlet
转载于：https://blog.csdn.net/ITcreater000/article/details/71759744