Java web含验证码及权限登录实例代码

package com.ningmeng.dao;
import java.sql.connection;
import java.sql.preparedstatement;
import java.sql.resultset;
import java.sql.sqlexception;
import com.ningmeng.model.user;
public class userdao {
 public user login(connection con,user user) throws sqlexception{
  user resultuser=null;
  string sql="select * from user where username=? and password=?";
  preparedstatement ps=con.preparestatement(sql);//
  ps.setstring(1, user.getusername());
  ps.setstring(2, user.getpassword());
  resultset rs=ps.executequery();
  if(rs.next()){
   resultuser=new user();
   resultuser.setusername(rs.getstring("username"));
   resultuser.setpassword(rs.getstring("password"));
  }
  return resultuser;
 }
}

package com.ningmeng.model;
public class user {
 private int id;
 private string username;
 private string password;
 public user() {
  super();
 }
 public user(string username, string password) {
  super();
  this.username = username;
  this.password = password;
 }
 public int getid() {
  return id;
 }
 public void setid(int id) {
  this.id = id;
 }
 public string getusername() {
  return username;
 }
 public void setusername(string username) {
  this.username = username;
 }
 public string getpassword() {
  return password;
 }
 public void setpassword(string password) {
  this.password = password;
 }
}

package com.ningmeng.util;
import java.sql.connection;
import java.sql.drivermanager;
import java.sql.sqlexception;
 public class dbutil {
 private string url="jdbc:mysql://localhost:3306/db-jsp";
 private string user="root";
 private string password="123";
 private string driver="com.mysql.jdbc.driver";
 public connection getcon() throws exception{
     class.forname(driver);
    connection con=drivermanager.getconnection(url, user, password);
    return con;
 }
 public static void getclose(connection con) throws sqlexception{
  if(con!=null){
   con.close();
  }
 }
 /*public static void main(string[] args) {
  dbutil db=new dbutil();
  try {
   db.getcon();
   system.out.println("测试连接数据库，连接成功");
  } catch (exception e) {
   // todo auto-generated catch block
   e.printstacktrace();
   system.out.println("测试连接数据库，连接失败");
  }
 }*/
}

package com.ningmeng.web;
import java.io.ioexception;
import java.sql.connection;
import java.io.*;
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 javax.servlet.http.*;
import com.ningmeng.dao.userdao;
import com.ningmeng.model.user;
import com.ningmeng.util.dbutil;
public class loginservlet extends httpservlet{
 dbutil db=new dbutil();
 userdao userdao=new userdao();
 /**
  * 
  */
 private static final long serialversionuid = 1l;
 @override
 protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
  this.dopost(request, response);
 }
 @override
 protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
  string username=request.getparameter("username");
  string password=request.getparameter("password");
  string checkcode=request.getparameter("checkcode");
  httpsession session=request.getsession();
  //session.getattribute("randcheckcode");
  string s = (string)session.getattribute("randcheckcode");
  if(!checkcode.equals(s))
  {
   response.sendredirect("linmao.jsp");
  }else{
   if(request.getparameter("ra").equals("l")){
  connection con=null;
  try {
   user user=new user(username,password);
   con=db.getcon();
   user currentuser=userdao.login(con, user);
   if(currentuser==null){
    //system.out.println("no");
    request.setattribute("error", "用户名或者密码错误");
    request.setattribute("username", username);
    request.setattribute("password", password);
    request.getrequestdispatcher("login.jsp").forward(request, response);
   }else{
    //system.out.println("yes");
    httpsession session1=request.getsession();
    session1.setattribute("currentuser",currentuser);
    response.sendredirect("main.jsp");
   }
  } catch (exception e) {
   // todo auto-generated catch block
   e.printstacktrace();
   }
  }
   else{
    response.sendredirect("linmao.jsp");
   }
  }
 }
 }

package com.servlet;
import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;
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 javax.imageio.imageio;
public class picturecheckcode extends httpservlet {
 private static final long serialversionuid = 1l;
 public picturecheckcode() {
  super();
 }
 public void destroy() {
  super.destroy(); 
 }
 public void init() throws servletexception {
  super.init();
 }
 /*该方法主要作用是获得随机生成的颜色*/ 
 public color getrandcolor(int s,int e){
  random random=new random ();
  if(s>255) s=255;
  if(e>255) e=255;
  int r,g,b;
  r=s+random.nextint(e-s); //随机生成rgb颜色中的r值
  g=s+random.nextint(e-s); //随机生成rgb颜色中的g值
  b=s+random.nextint(e-s); //随机生成rgb颜色中的b值
  return new color(r,g,b);
 }
 @override
 public void service(httpservletrequest request, httpservletresponse response)
   throws servletexception, ioexception {
  //设置不缓存图片
  response.setheader("pragma", "no-cache");
  response.setheader("cache-control", "no-cache");
  response.setdateheader("expires", 0);
  //指定生成的响应图片,一定不能缺少这句话,否则错误.
  response.setcontenttype("image/jpeg");
  int width=86,height=33;  //指定生成验证码的宽度和高度
  bufferedimage image=new bufferedimage(width,height,bufferedimage.type_int_rgb); //创建bufferedimage对象,其作用相当于一图片
  graphics g=image.getgraphics();  //创建graphics对象,其作用相当于画笔
  graphics2d g2d=(graphics2d)g;  //创建grapchics2d对象
  random random=new random();
  font mfont=new font("楷体",font.bold,20); //定义字体样式
  g.setcolor(getrandcolor(200,250));
  g.fillrect(0, 0, width, height); //绘制背景
  g.setfont(mfont);     //设置字体
  g.setcolor(getrandcolor(180,200));
  //绘制100条颜色和位置全部为随机产生的线条,该线条为2f
  for(int i=0;i<100;i++){
   int x=random.nextint(width-1);
   int y=random.nextint(height-1);
   int x1=random.nextint(6)+1;
   int y1=random.nextint(12)+1;
   basicstroke bs=new basicstroke(2f,basicstroke.cap_butt,basicstroke.join_bevel); //定制线条样式
   line2d line=new line2d.double(x,y,x+x1,y+y1);
   g2d.setstroke(bs);
   g2d.draw(line);  //绘制直线
  }
  //输出由英文，数字，和中文随机组成的验证文字，具体的组合方式根据生成随机数确定。
  string srand="";
  string ctmp="";
  int itmp=0;
  //制定输出的验证码为四位
  for(int i=0;i<4;i++){
   switch(random.nextint(3)){
    case 1:  //生成a-z的字母
      itmp=random.nextint(26)+65;
      ctmp=string.valueof((char)itmp);
      break;
    default:
      itmp=random.nextint(10)+48;
      ctmp=string.valueof((char)itmp);
      break;
   }
   srand+=ctmp;
   color color=new color(20+random.nextint(110),20+random.nextint(110),random.nextint(110));
   g.setcolor(color);
   //将生成的随机数进行随机缩放并旋转制定角度 ps.建议不要对文字进行缩放与旋转,因为这样图片可能不正常显示
   /*将文字旋转制定角度*/
   graphics2d g2d_word=(graphics2d)g;
   affinetransform trans=new affinetransform();
   trans.rotate((45)*3.14/180,15*i+8,7);
   /*缩放文字*/
   float scalesize=random.nextfloat()+0.8f;
   if(scalesize>1f) scalesize=1f;
   trans.scale(scalesize, scalesize);
   g2d_word.settransform(trans);
   g.drawstring(ctmp, 15*i+18, 14);
  }
  httpsession session=request.getsession(true);
  session.setattribute("randcheckcode", srand);
  g.dispose(); //释放g所占用的系统资源
  imageio.write(image,"jpeg",response.getoutputstream()); //输出图片
 }
}

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="webapp_id" version="3.0">
 <display-name>web04</display-name>
 <welcome-file-list>
 <welcome-file>login.jsp</welcome-file>
  <welcome-file>main.jsp</welcome-file>
 </welcome-file-list>
 <servlet>
  <servlet-name>loginservlet</servlet-name>
  <servlet-class>com.ningmeng.web.loginservlet</servlet-class>
 </servlet>
 <servlet>
 <description>输出验证码</description>
 <display-name>this is the display name of my j2ee component</display-name>
 <servlet-name>picturecheckcode</servlet-name>
 <servlet-class>com.servlet.picturecheckcode</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>loginservlet</servlet-name>
  <url-pattern>/login</url-pattern>
 </servlet-mapping>
 <servlet-mapping>
 <servlet-name>picturecheckcode</servlet-name>
 <url-pattern>/picturecheckcode</url-pattern>
 </servlet-mapping>
</web-app>

<%@ page language="java" contenttype="text/html; charset=utf-8"
 pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>insert title here</title>
<script language="javascript">
function myreload() {
 document.getelementbyid("createcheckcode").src = document
   .getelementbyid("createcheckcode").src
   + "?nocache=" + new date().gettime();
}
</script>
</head>
<body>
<form action="login" method="post">
 <table>
  <tr>
   <th colspan="2">登录界面</th>
  </tr>
  <tr>
   <td>账号：</td>
   <td><input type="text" id="username" name="username" value="${username}"></td>
  </tr>
  <tr>
   <td>密码：</td>
   <td><input type="password" id="password" name="password" value="${password}"></td>
  </tr>
  <tr>
   <td>验证码：</td>
   <td><input name="checkcode" type="text" id="checkcode" title="验证码区分大小写"
    size="8" ,maxlength="4" />
   <img src="picturecheckcode" id="createcheckcode" align="middle">
   <a href="" onclick=" rel="external nofollow" myreload()"> 看不清,换一个</a>
  </tr>
  <tr>
   <td>类型：</td>
   <td>
   <input type="radio" name="ra" value="l" checked="checked"/>一般研究人员
   <input type="radio" name="ra" value="m" />管理员研究人员
   </td>
  </tr>
  <tr>
   <td>
   <input type="submit" value="提交">
   <font color="red">${error}</font>
   </td>
  </tr>
 </table>
</form>
</body>
</html>

<%@ page language="java" contenttype="text/html; charset=utf-8"
 pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>insert title here</title>
</head>
<body>
<p>登录成功</p>
当前用户：${currentuser.username}<br/>
当前密码：${currentuser.password}<br/>
</body>
</html>

<%@ page language="java" import="java.util.*" pageencoding="iso-8859-1"%>
<%
string path = request.getcontextpath();
string basepath = request.getscheme()+"://"+request.getservername()+":"+request.getserverport()+path+"/";
%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
 <head>
 <base href="<%=basepath%>" rel="external nofollow" >
 <title>my jsp 'linmao.jsp' starting page</title>
 <meta http-equiv="pragma" content="no-cache">
 <meta http-equiv="cache-control" content="no-cache">
 <meta http-equiv="expires" content="0"> 
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
 <meta http-equiv="description" content="this is my page">
 <!--
 <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" >
 -->
 </head>
 <body>
 this is my jsp page. <br>
 </body>
</html>