JavaWeb用户登录功能的实现

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、css、query：页面

Servlet、java：后台

运行效果图：

Login.html代码：

登录

用户名:

密码:

验证码:

JQuery代码：login.js

$(function(){

$(".loginform_submit").click(function(){

if(checkInput()) {

$("form").action("/loginServlet");

}else{

return false;

}

});

$(".validationCode_img").click(function(){

$(".validationCode_img").attr("src","/UserLogin/Sample1/validationCode?"+Math.random());

});

function checkInput(){

//判断用户名

if($("input[name=username]").val() == null || $("input[name=username]").val() == ""){ alert("用户名不能为空");

$("input[name=username]").focus();

return false;

}

//判断密码

if($("input[name=password]").val() == null || $("input[name=password]").val() == ""){ alert("密码不能为空");

$("input[name=password]").focus();

return false;

}

//判断验证码

if($("input[name=validationCode]").val() == null || $("input[name=validationCode]").val() == ""){

alert("验证码不能为空");

$("input[name=validationCode]").focus();

return false;

}

return true;

}

});

生成验证码的Servlet：ValidationCode.java

package https://www.360docs.net/doc/186780640.html,erlogin.sample;

import javax.imageio.ImageIO;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import java.awt.*;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Random;

/**

* Created by zhang on 2014/9/13.

*/

public class ValidationCode extends HttpServlet{

@Override

protected void doGet(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

//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3条语句的支持也不同

//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");

resp.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.setColor(getRandomColor(180, 250));

g.fillRect(0, 0, width, height);

g.setFont(new Font("Times New Roman",Font.ITALIC,height));

g.setColor(getRandomColor(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[] fontNames = {"Times New Roman","Book antiqua","Arial"};

//随机生成3-5个验证码

for(int i = 0; i < 4; i++){

//随机设置当前验证码的字符的字体

g.setFont(new Font(fontNames[random.nextInt(3)],Font.ITALIC,height));

//随机获得当前验证码的字符

char codeChar = codeChars.charAt(random.nextInt(charsLength));

validationCode.append(codeChar);

//随机设置当前验证码字符的颜色

g.setColor(getRandomColor(10, 100));

//在图形上输出验证码字符，x和y都是随机生成的

g.drawString(String.valueOf(codeChar), 16*i + random.nextInt(7), height-random.nextInt(6));

}

//获得HttpSession对象

HttpSession session = req.getSession();

//设置session对象5分钟失效

session.setMaxInactiveInterval(5*60);

//将验证码保存在session对象中,key为validation_code

session.setAttribute("validation_code", validationCode.toString());

//关闭Graphics对象

g.dispose();

OutputStream outS = resp.getOutputStream();

ImageIO.write(image, "JPEG", outS);

}

@Override

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

doGet(req,resp);

}

//图形验证码的字符集，系统将随机从这个字符串中选择一些字符作为验证码

private static String codeChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

//返回一个随机颜色

private static Color getRandomColor(int minColor, int maxColor){

Random random = new Random();

if(minColor > 255){

minColor = 255;

}

if(maxColor > 255){

maxColor = 255;

}

//获得r的随机颜色值

int red = minColor + random.nextInt(maxColor-minColor);

//g

int green = minColor + random.nextInt(maxColor-minColor);

//b

int 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)

package https://www.360docs.net/doc/186780640.html,erlogin.sample.dbmanager;

import java.beans.Statement;

import java.sql.*;

public class ManageSQLServer2008 {

//数据库的驱动名

private final String dbDriver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";

//数据库的url地址

private final String url = "jdbc:sqlserver://localhost:1433;databaseName=zhDemo";

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();

//System.out.println("加载驱动成功");

} catch (Exception e) {

e.printStackTrace();

System.err.println("数据库驱动加载失败");

}

//获取数据库链接

try {

conn = DriverManager.getConnection(url,userName,password);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

System.err.println("获取数据库链接失败");

}

}

//执行各种SQL语句的方法

private ResultSet execSQL(String sql,Object... args) 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 < args.length; i++){

pStmt.setObject(i+1, args[i]);

}

//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(String username,String password){

boolean has_username = false;

boolean password_correct = false;

ResultSet rs = null;

try {

rs = execSQL("select * from zh_users");

} catch (SQLException e) {

System.err.println("查询数据库出错");

e.printStackTrace();

return null;

}

try {

while(rs.next()){

String temp_username = rs.getString("user_name").trim();

String temp_password = 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) {

System.err.println("操作ResultSet出错");

e.printStackTrace();

}

return "hasNoUserName";

}

}

用于处理用户登录的Servlet:LoginServlet.java

package https://www.360docs.net/doc/186780640.html,erlogin.sample;

import https://www.360docs.net/doc/186780640.html,erlogin.sample.dbmanager.ManageSQLServer2008;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import java.io.IOException;

import java.io.OutputStream;

/**

* Created by zhang on 2014/9/13.

*/

public class LoginServlet extends HttpServlet{

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

OutputStream out = resp.getOutputStream();

String username = req.getParameter("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)){

System.out.println("验证码正确");

}else{

System.out.println("验证码错误");

}

ManageSQLServer2008 mss = new ManageSQLServer2008();

String result = mss.checkUser(username,password);

if (result.equals("hasUserNameAndPasswordCorrect")) {

System.out.println("用户名和密码均正确");

} else if (result.equals("hasUserNameButPasswordInCorrect")) {

System.out.println("用户名正确,密码不正确");

} else if (result.equals("hasNoUserName")) {

System.out.println("没有此用户");

}

//转发到result.jsp

RequestDispatcher rd = req.getRequestDispatcher("Login.html");

rd.forward(req, resp);

}

@Override

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

doGet(req,resp);

}

}

web.xml文件的配置:

loginServlet

https://www.360docs.net/doc/186780640.html,erlogin.sample.LoginServlet

loginServlet

/loginServlet

validationCode

https://www.360docs.net/doc/186780640.html,erlogin.sample.ValidationCode

validationCode

/validationCode

最后的style.css代码，太多了，而且有点乱，所以就没有贴出来，至于CSS代码，大家可以去网上下载：https://www.360docs.net/doc/186780640.html,/tag_moban/htmlMoBan.html这个上面就有好多，大家根据喜好选择一个，然后稍加即可。