JavaWeb用户登录功能的实现

1、JavaWeb用户登录功能的实现大四快毕业了， 3年多的时间中，乱七八糟得学了一大堆， 想趁找工作之前把所学的东西整理一遍， 所以就尝试着做一个完整的JavaWeb系统，这几天试着做了一个用户登录的功能，分享给大家，肯定有很多不完善的地方，希望大家提提宝贵的意见，必将努力完善它。我贴出此篇博客的目的是， 将一些以后有可能用到的重复性的代码保存下来，用于以后需要时直接复制粘贴，所以，此篇博客大部分都是代码，讲解性的语句并不多，如果大家看得头疼，不如不看，以 后万一用到的话再拿过来修修改改即可。有可能用得到的部分：生成验证码的Java类、操作数据库的 Java类用户登录模块采用了多种语言：Html

2、、css、query: 页面Servlet、java： 后台运行效果图:Login.html 代码: 登录界面 script src=js/login.js 登录 form action = /UserLogin/Sample1/loginServlet 用户名：input type=text class=loginform_input name=username / 密码：input type=password class=loginform_input name=password / 验证码：input type = text class=loginform_input_validatio

3、nCode name =validationCode/JQuery 代码：login.js$(function()$(.loginform_submit).click(function()if(checkInput() $(form).action(/loginServlet);elsereturn false;)；$(.validationCode_img).click(function()$(.validationCode_img).attr(src,/UserLogin/Sample1/validationCode?+Math.random();)；function checkInput

4、()判断用户名if($(inputname=username).val() = null | $(inputname=username).val() = )alert(用户名不能为空)；$(inputname=username).focus();return false;判断密码if($(inputname=password).val() = null | $(inputname=password).val() = ) alert(密码不能为空);$(inputname=password).focus();return false;判断验证码if($(inputname=validationC

5、ode).val() = null | $(inputname=validationCode).val() = ) alert(验证码不能为空);$(inputname=validationCode).focus();return false;return true;);生成验证码的 Servlet: ValidationCode.javaimport java.awt.*;/* Created by zhang on 2014/9/13.*/public class ValidationCode extends HttpServletOverrideprotected void doGet(

6、HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException /获得验证码集合的长度int charsLength = codeChars.length();下面3条记录是关闭客户端浏览器的缓冲区3条语句的支持这3条语句都可以关闭浏览器的缓冲区，但是由于浏览器的版本不同，对这也不同因此，为了保险起见，同时使用这3条语句来关闭浏览器的缓冲区resp.setHeader(ragma, No-cache);resp.setHeader(Cache-Control, no-cache);re

7、sp.setDateHeader(Expires, 0);设置图形验证码的长和宽int width = 90, height = 30;BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics(); 获得用于输出文字的Graphics 对象Random random = new Random();g.setC010r(getRandomC010r(180, 250);g.fillRect(0, 0, width, height);

8、g.setFont(new Font(Times New Roman,Font.ITALIC,height);g.setC010r(getRandomC010r(120, 180);用户保存最后随机生成的验证码StringBuilder validationCode = new StringBuilder();验证码的随机字体String口 fontNames = Times New Roman,Book antiqua,Arial;随机生成3-5个验证码for(int i = 0; i 255)minColor = 255;if(maxColor 255)maxColor = 255;/获彳

9、导r的随机颜色值int red = minColor + random.nextInt(maxColor-minColor);/gint green = minColor + random.nextInt(maxColor-minColor);/bint blue = minColor + random.nextInt(maxColor-minColor);return new Color(red,green,blue);操作数据库的代码：ManageSQLServer2008.java(本人使用的数据库为 SQLServer 2008)import java.sql.*;public cla

10、ss ManageSQLServer2008 /数据库的驱动名/数据库的url地址private final String userName = sa;private final String password = 123;private Connection conn = null;public ManageSQLServer2008()加载数据库驱动try Class.forName(dbDriver).newInstance(); catch (Exception e) e.printStackTrace();/获取数据库链接try conn = DriverManager.getCon

11、nection(url,userName,password); catch (SQLException e) / TODO Auto-generated catch block e.printStackTrace();执行各种SQL语句的方法private ResultSet execSQL(String sql,Objectargs) throws SQLException/建立 PreparedStatement对象PreparedStatement pStmt = conn.prepareStatement(sql);为pStmt对象设置SQL参数值for(int i = 0; i ar

12、gs.length; i+) pStmt.setObject(i+1, argsi);执行SQL语句pStmt.execute();返回结果集，如果执行的SQL语句不返回结果集，则返回 null return pStmt.getResultSet();private void closeSQLConn()关闭数据库链接if(conn != null) try conn.close(); catch (SQLException e) / TODO Auto-generated catch block e.printStackTrace();public String checkUser(Stri

13、ng username,String password) boolean has_username = false;boolean password_correct = false;ResultSet rs = null;try rs = execSQL(select * from zh_users); catch (SQLException e) e.printStackTrace(); return null;try while(rs.next()String temp_username = rs.getString(user_name).trim();String temp_passwo

14、rd = rs.getString(password_md5).trim(); if(username.equals(temp_username) has_username = true;if(password.equals(temp_password) password_correct = true;return hasUserNameAndPasswordCorrect; return hasUserNameButPasswordInCorrect; catch (SQLException e) e.printStackTrace(); return hasNoUserName;用于处理用

15、户登录的 Servlet:LoginServlet.java/* Created by zhang on 2014/9/13.*/public class LoginServlet extends HttpServletOverrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException OutputStream out = resp.getOutputStream();String username = req.getParamet

16、er(username);String password = req.getParameter(password);String validationCode = req.getParameter(validationCode);HttpSession session = req.getSession();String validation_code = (String)session.getAttribute(validation_code);if(validationCode.equalsIgnoreCase(validation_code)elseManageSQLServer2008

17、mss = new ManageSQLServer2008();String result = mss.checkUser(username,password);if (result.equals(hasUserNameAndPasswordCorrect) else if (result.equals(hasUserNameButPasswordInCorrect) else if (result.equals(hasNoUserName) 转发到 result.jspRequestDispatcher rd = req.getRequestDispatcher(Login.html);rd.forward(req, resp);Overrideprotected void doPost(HttpSe