java web验证码实现代码分享
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2024-03-12 15:11:56
验证码的作用：通常的登录或者注册系统时，都会要求用户输入验证码，以此区别用户行为和计算机程序行为，目的是有人防止恶意注册、暴力破解密码等。
实现验证码的思路：用 se...
验证码的作用：通常的登录或者注册系统时，都会要求用户输入验证码，以此区别用户行为和计算机程序行为，目的是有人防止恶意注册、暴力破解密码等。
实现验证码的思路：用 server 实现随机生成数字和字母组成图片的功能，用 jsp 页面实现显示验证码和用户输入验证码的功能，再用 server 类分别获取图片和用户输入的数据，判断两个数据是否一致。
代码实现
1.编写数字、英文随机生成的 server 类，源码：
package com;
import java.awt.color;
import java.awt.font;
import java.awt.graphics;
import java.awt.image.bufferedimage;
import java.io.bytearrayoutputstream;
import java.io.ioexception;
import java.io.printwriter;
import javax.imageio.imageio;
import javax.servlet.servletexception;
import javax.servlet.servletoutputstream;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import javax.servlet.http.httpsession;
public class logcheck extends httpservlet {
public logcheck() {
super();
}
public void destroy() {
super.destroy();
}
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request, response);
}
/*实现的核心代码*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
response.setcontenttype("image/jpeg");
httpsession session=request.getsession();
int width=60;
int height=20;
//设置浏览器不要缓存此图片
response.setheader("pragma", "no-cache");
response.setheader("cache-control", "no-cache");
response.setdateheader("expires", 0);
//创建内存图像并获得图形上下文
bufferedimage image=new bufferedimage(width, height,bufferedimage.type_int_rgb);
graphics g=image.getgraphics();
/*
* 产生随机验证码
* 定义验证码的字符表
*/
string chars="0123456789abcdefghijklmnopqrstuvwxyz";
char[] rands=new char[4];
for(int i=0;i<4;i++){
int rand=(int) (math.random() *36);
rands[i]=chars.charat(rand);
}
/*
* 产生图像
* 画背景
*/
g.setcolor(new color(0xdcdcdc));
g.fillrect(0, 0, width, height);
/*
* 随机产生120个干扰点
*/
for(int i=0;i<120;i++){
int x=(int)(math.random()*width);
int y=(int)(math.random()*height);
int red=(int)(math.random()*255);
int green=(int)(math.random()*255);
int blue=(int)(math.random()*255);
g.setcolor(new color(red,green,blue));
g.drawoval(x, y, 1, 0);
}
g.setcolor(color.black);
g.setfont(new font(null, font.italic|font.bold,18));
//在不同高度输出验证码的不同字符
g.drawstring(""+rands[0], 1, 17);
g.drawstring(""+rands[1], 16, 15);
g.drawstring(""+rands[2], 31, 18);
g.drawstring(""+rands[3], 46, 16);
g.dispose();
//将图像传到客户端
servletoutputstream sos=response.getoutputstream();
bytearrayoutputstream baos=new bytearrayoutputstream();
imageio.write(image, "jpeg", baos);
byte[] buffer=baos.tobytearray();
response.setcontentlength(buffer.length);
sos.write(buffer);
baos.close();
sos.close();
session.setattribute("checkcode", new string(rands));
}
public void init() throws servletexception {
// put your code here
}
}
2.用于显示验证码的页面：
<%@ page language="java" import="java.util.*" pageencoding="utf-8"%> <% 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%>"> <title>index</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"> --> </head> <body> <form action="yanzheng" method="post"> <input type="text" name="name" size="5" maxlength="4"> <a href="index.jsp"><img border="0" src="logcheck"></a><br><br>      <input type="submit" value="提交"> </form> </body> </html>
3.用于检验输入的验证码是否正确：
package com;
import java.io.ioexception;
import java.io.printwriter;
import javax.jms.session;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import javax.servlet.http.httpsession;
public class yanzheng extends httpservlet {
public yanzheng() {
super();
}
public void destroy() {
super.destroy();
}
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request, response);
}
/*核心代码*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
string info=null;
/*获取输入的值*/
string value1=request.getparameter("name");
/*获取图片的值*/
httpsession session=request.getsession();
string value2=(string)session.getattribute("checkcode");
/*对比两个值（字母不区分大小写）*/
if(value2.equalsignorecase(value1)){
info="验证码输入正确";
}else{
info="验证码输入错误";
}
system.out.println(info);
request.setattribute("info", info);
request.getrequestdispatcher("/login.jsp").forward(request, response);
}
public void init() throws servletexception {
// put your code here
}
}
4.显示输入结构界面（输入验证码是否正确）：
<%@ page language="java" import="java.util.*" pageencoding="utf-8"%>
<%
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%>">
<title>my jsp 'login.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">
-->
</head>
<body>
<%=request.getattribute("info") %>
</body>
</html>
5.项目结构、效果截图：
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