jsp+tomcat 如何让网站加上验证用户功能?

给你3种生成随即数的程序
<%! String sVerifyCode; //验证码字符串  %> <%//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
response.reset();try{
// 将认证码存入SESSION
//调用 runVerifyCode(int i) ,把i改成所要的验证码位数
VerifyCode VC = new VerifyCode();
session.setAttribute("VerifyCode",VC.runVerifyCode(4));
//session.setMaxInactiveInterval(60);// 输出图象到页面
sVerifyCode = (String)session.getAttribute("VerifyCode");
OutputStream outs = response.getOutputStream();
ImageIO.write(VC.CreateImage(sVerifyCode),"JPEG",outs);
}catch(Exception e){
return;
   }
%>
代码如下
import java.awt.*;//导入类
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;
public class VerifyCode {
static Random r = new Random();
static String ssource = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"  + "abcdefghijklmnopqrstuvwxyz" + "0123456789";
static char[] src = ssource.toCharArray();
//产生随机字符串private static String randString (int length){
char[] buf = new char[length];
int rnd;
for(int i=0;i<length;i++){
rnd = Math.abs(r.nextInt()) % src.length;buf[i] = src[rnd];
}
return new String(buf);
}//调用该方法，产生随机字符串,
//参数i: 为字符串的长度
public String runVerifyCode(int i){
String VerifyCode = randString(i);
return VerifyCode;
}
//给定范围获得随机颜色
public Color getRandColor(int fc,int bc)
{
   Random random = new Random();
   if(fc>255) fc=255;
   if(bc>255) bc=255;
   int r=fc+random.nextInt(bc-fc);
   int g=fc+random.nextInt(bc-fc);
   int b=fc+random.nextInt(bc-fc);
   return new Color(r,g,b);
   }

  //调用该方法将得到的验证码生成图象
  //sCode:传递验证码 w:图象宽度 h:图象高度
  public BufferedImage CreateImage(String sCode)
  {
  try{
  //字符的字体
Font CodeFont = new Font("Arial Black",Font.PLAIN,16);
int iLength = sCode.length();//得到验证码长度
int width=22*iLength, height=20;//图象宽度与高度
int CharWidth = (int)(width-24)/iLength;//字符距左边宽度
int CharHeight = 16;    //字符距上边高度// 在内存中创建图象
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);// 获取图形上下文
Graphics g = image.getGraphics();//生成随机类
Random random = new Random();// 设定背景色
g.setColor(getRandColor(200,240));
g.fillRect(0, 0, width, height);//设定字体
g.setFont(CodeFont);//画随机颜色的边框
g.setColor(getRandColor(10,50));
g.drawRect(0,0,width-1,height-1);// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
  int x = random.nextInt(width);
  int y = random.nextInt(height);
  int xl = random.nextInt(12);
  int yl = random.nextInt(12);
  g.drawLine(x,y,x+xl,y+yl);
}
for (int i=0;i<iLength;i++)
{
String rand = sCode.substring(i,i+1);
// 将认证码显示到图象中
g.setColor(new Color(20+random.nextInt(60),20+random.nextInt(120),20+random.nextInt(180)));
g.drawString(rand,CharWidth*i+14,CharHeight);
}
// 图象生效
g.dispose();
return image;
}catch(Exception e){
//e.printStackTrace();
//System.out.println(e.getMessage());
}
return null;
}//测试
public static void main(String[] args){
//VerifyCode vc = new VerifyCode();
//String s1 = vc.runVerifyCode(4);
//Fun.DreamNewsTitle;System.out.println(s1);
//Image im = vc.CreateImage(s1);
//Graphics g = im.getGraphics();
//g.drawImage(im,20,20,this);
//g.drawString(s1,20,20);}
}

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletException;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;
import java.io.IOException;/**
* @author <a href="mailto:[email protected]">Jade Yuan</a>
* @version 2006-3-9 18:34:36
*/
public class ImageServlet extends HttpServlet {
    private static final String CONTENT_TYPE = "image/jpeg";
//  private static final String [] FontNames={"SansSerif","Serif","MonoSpaced","Dialog","DialogInput"};    //Initialize global variables
    public void init() throws ServletException {
    }    //Process the HTTP Get request
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        response.setContentType(CONTENT_TYPE);
        response.setHeader("Pragma", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);        // 在内存中创建图象
        int width = 60, height = 20;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);        // 获取图形上下文
        Graphics g = image.createGraphics();        //生成随机类
        Random random = new Random();        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);        //设定字体
        g.setFont(new Font("DialogInput", Font.ITALIC, 18));
        //    g.setFont(new Font(FontNames[random.nextInt(6)%5], Font.ITALIC, 18));
        //画边框
        //g.setColor(new Color());
        //g.drawRect(0,0,width-1,height-1);        // 随机产生255条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 255; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }// 取随机产生的认证码(4位数字)
//String rand = request.getParameter("rand");
//rand = rand.substring(0,rand.indexOf("."));
        String sRand = "";
        for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110),
                    20 + random.nextInt(110))); //调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(rand, 13 * i + 6, 16);
        }
        //System.out.println("validate code=" + sRand);        // 将认证码存入SESSION
        HttpSession session = request.getSession();
        session.setAttribute("rand", sRand);        // 图象生效
        g.dispose();        // 输出图象到页面
        ServletOutputStream outputstream = response.getOutputStream();
        ImageIO.write(image, "JPEG", outputstream);
    }    //Clean up resources
    public void destroy() {
    }    Color getRandColor(int fc, int bc) { //给定范围获得随机颜色
        Random random = new Random();
        if (fc > 255) {
            fc = 255;
        }
        if (bc > 255) {
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }    public static void main(String[] args) {    }
}

<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
        Random random = new Random();
        if(fc>255) fc=255;
        if(bc>255) bc=255;
        int r=fc+random.nextInt(bc-fc);
        int g=fc+random.nextInt(bc-fc);
        int b=fc+random.nextInt(bc-fc);
        return new Color(r,g,b);
        }
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// 获取图形上下文
Graphics g = image.getGraphics();//生成随机类
Random random = new Random();// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
        int xl = random.nextInt(12);
        int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}// 取随机产生的认证码(4位数字)
String sRand="";
for (int i=0;i<4;i++){
    String rand=String.valueOf(random.nextInt(10));
    sRand+=rand;
    // 将认证码显示到图象中
    g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
    g.drawString(rand,13*i+6,16);
}// 将认证码存入SESSION
session.setAttribute("rand",sRand);// 图象生效
g.dispose();// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>保存为images.jsp
再在文件中调用就行了
<input name=rand type=text value="" size="10" maxlength=4><img border=0 src="images.jsp">
<%
String rand = (String)session.getAttribute("rand");
//在images.jsp里已经把rand存入SESSION了，这里调用就行
String input = request.getParameter("rand");
if (rand.equals(input))
{
//你想进行的操作
}
else
{
String pstr="<script language='javascript'>alert('验证码输入错误，请重新输入!');";
pstr = pstr + "</script>";
out.println(pstr);
}
%>
这3中方法一种我写的两外两个是转载的

楼主是要的弹出一个对话框的安全realm配置对吧    <security-constraint>
    <web-resource-collection>
      <web-resource-name>HTMLManger and Manager command</web-resource-name>
      <url-pattern>/*</url-pattern>
    </web-resource-collection>
    <auth-constraint>
       
       <role-name>manager</role-name>
    </auth-constraint>
  </security-constraint>  
  <login-config>
    <auth-method>BASIC</auth-method>
    <realm-name>Tomcat Manager Application</realm-name>
  </login-config>  
  <security-role>
    <description>
      The role that is required to log in to the Manager Application
    </description>
    <role-name>manager</role-name>
  </security-role>
  在你的web.xml里面加上这一段就可以了

我是tomcat5.5 然后在conf/tomcat-users.xml 里面加上与上面一样的用户和角色就可以了

你照抄一下 tomcat自带的那个例子就可以了我刚刚也是从manager醒目下面考过来的

谢谢大家,特别是interpb(曾曾胡，深怕情多累美人！),我就是要弹出对话框.

用TOMCAT作为容器。我编写了TEST。JSP文件放在WEBAPPS目录下新建的MYAPP目录中（已经放置了WEB-INF目录以及。XML文件）。为什么找不到TEST。JSP 文件。提示是404错误

加个输入的表单啊页面头部判断用户的session

调试易

jsp+tomcat 如何让网站加上验证用户功能?

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