会JSP验证的的进 - 编程论坛

#2

wanghongxian2007-06-27 23:05

回复：（wanghongxian）会JSP验证的的进

我想做一个JSP上面的验证码，但是不知道怎么写，有例子的大家帮忙给我一个，谢谢

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#3

enlangs2007-06-28 18:07

调用方法
<img src="http://...../getImg">

原理，在servlet中随机生成一个4位数字1000-9999
然后把这数字写入session
输出一个图片，上面写有这四个数字
在服务器端根据用户输入的数字和
session中的值比较。

[CODE]
package com.schoolwx.util;
import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.awt.*;
import java.awt.image.*;

/**
* Title: getImg.java
* Description: 这个class主要实现随机生成一个4位数的验证码，并写入session，
* Copyright: Copyright (c) 2003
* Company: 蓝星软件
* @author falcon
* @version 1.1
*/

public class getImg extends HttpServlet {

private Font mFont=new Font("宋体", Font.PLAIN,12);//设置字体
//处理post
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException {

doGet(request,response);
}
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException {
//取得一个1000-9999的随机数
String s="";

int intCount=0;

intCount=(new Random()).nextInt(9999);//

if(intCount<1000)intCount+=1000;

s=intCount+"";

//对session付值。

HttpSession session=request.getSession (true);

session.setAttribute("getImg",s);

response.setContentType("image/gif");

ServletOutputStream out=response.getOutputStream();

BufferedImage image=new BufferedImage(35,14,BufferedImage.TYPE_INT_RGB);

Graphics gra=image.getGraphics();
//设置背景色
gra.setColor(Color.yellow);

gra.fillRect(1,1,33,12);
//设置字体色
gra.setColor(Color.black);

gra.setFont(mFont);
//输出数字
char c;

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

c=s.charAt(i);

gra.drawString(c+"",i*7+4,11); //7为宽度，11为上下高度位置

}

JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);

encoder.encode(image);

out.close();

}

}[/CODE]
http://blog.csdn.net/lixiaolong_blog/archive/2007/01/25/1493417.aspx

#4

enlangs2007-06-28 18:11

生成有4个随机数字和杂乱背景的图片，数字和背景颜色会改变，服务器端刷新（用history.go(-1)也会变）
产生验证码图片的文件image.jsp

<%@ 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());
%>

使用验证码图片的文件a.jsp

<%@ page contentType="text/html;charset=gb2312" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>认证码输入页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<form method=post action="check.jsp">
<table>
<tr>
<td align=left>系统产生的认证码：</td>
<td><img border=0 src="image.jsp"></td>
</tr>
<tr>
<td align=left>输入上面的认证码：</td>
<td><input type=text name=rand maxlength=4 value=""></td>
</tr>
<tr>
<td colspan=2 align=center><input type=submit value="提交检测"></td>
</tr>
</form>
</body>
</html>

验证的页面check.jsp

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<html>
<head>
<title>认证码验证页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>

<body>
<%
String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为： <%= rand %><br>
您输入的认证码为： <%= input %><br>
<br>
<%
if (rand.equals(input)) {
%>
<font color=green>输入相同，认证成功！</font>
<%
} else {
%>
<font color=red>输入不同，认证失败！</font>
<%
}
%>
</body>
</html>

#5

wanghongxian2007-06-28 23:23

先谢谢你，我把三个文件做好后，运行a.jsp后，为什么图片那个位置，不能显示，那个图片我要准备吗

#6

风月_无边2007-06-29 09:24

图片肯定是自动生成的！！

#7

千里冰封2007-06-29 09:30

[CODE]<%@page contentType="image/jpeg"%>
<%@page pageEncoding="UTF-8"%>
<%@ page import="java.awt.*,javax.imageio.*,java.io.*,java.util.*,java.awt.image.*" %>
<%--
The taglib directive below imports the JSTL library. If you uncomment it,
you must also add the JSTL library to the project. The Add Library... action
on Libraries node in Projects view can be used to add the JSTL 1.1 library.
--%>
<%--
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
--%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%
java.util.List<String> fonts=new ArrayList<String>();
GraphicsEnvironment.getLocalGraphicsEnvironment().preferLocaleFonts();
String[] names=GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames(Locale.CHINA);
for(String s:names){
char c=s.charAt(0);
if(Character.isLowerCase(c)||Character.isUpperCase(c)){

}else{
fonts.add(s);
}
}
BufferedImage bi=new BufferedImage(200,50,BufferedImage.TYPE_INT_RGB);
Graphics2D g=bi.createGraphics();
char[] cs={'0','1','2','3','4','5','6','7','8','9'};
char[] use=new char[4];
g.setColor(new Color(240,240,240));
g.fillRect(0,0,200,50);
for(int i=0;i<4;i++){
Point p=new Point(5+(i*((int)(Math.random()*10)+40)),40);
int size=0;
int[] sizes=new int[20];
for(int j=0;j<20;j++){
sizes[j]=30+j;
}
size=sizes[(int)(Math.random()*sizes.length)];
int face=0;
if(Math.random()*10>5){
face=Font.BOLD;
}else{
face=Font.ITALIC;
}
use[i]=cs[(int)(Math.random()*cs.length)];
g.setPaint(new GradientPaint(p.x,p.y,new Color((int)(Math.random()*256),0,(int)(Math.random()*256)),
p.x,p.y-size,new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256))));
g.setFont(new Font(fonts.get((int)(Math.random()*fonts.size())),face,size));
g.drawString(""+use[i],p.x,p.y);
}
g.setPaint(null);
for(int i=0;i<4;i++){
g.setColor(new Color((int)(Math.random()*0x00FFFFFFF)));
g.drawLine((int)(Math.random()*200),(int)(Math.random()*50),(int)(Math.random()*200),(int)(Math.random()*50));
}
Random random = new Random();
for (int i=0;i<88;i++) {
int x = random.nextInt(200);
int y = random.nextInt(50);
g.setColor(new Color((int)(Math.random()*0x00FFFFFFF)));
g.setStroke(new BasicStroke((float)(Math.random()*3)));
g.drawLine(x,y,x,y);
}
OutputStream ot=response.getOutputStream();
ImageIO.write(bi,"JPEG",ot);
out.close();
g.dispose();
%>[/CODE]

这是我去年写的一个验证码生成的图片

#8

enlangs2007-06-29 10:32

回复：（千里冰封）[CODE]

如果我要在验证码中加入字母的验证呢?

#9

wanghongxian2007-07-02 01:19

图片能够显示了，但是提交后出现下面错误，可能是空指向异常，错误是 check.jsp页面
HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

root cause

java.lang.NullPointerException
org.apache.jsp.check_jsp._jspService(check_jsp.java:67)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.

--------------------------------------------------------------------------------

#10

千里冰封2007-07-02 09:01

以下是引用enlangs在2007-6-29 10:32:22的发言：
如果我要在验证码中加入字母的验证呢?

一样的,把字母画出来就可以了,添加中文都行