JSP之验证码登陆(用JAVA绘制验证码)

阳光穿透心脏的1/2处 2024-02-18 20:17 73阅读 0赞

![20180520113528555][]

![20180520113613133][]

index.jsp代码

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>       
        <title>My JSP 'index.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">	
    	<script type="text/javascript">
    		function check_admin(form){
    			if(form.user.value==""){
    				alert("请输入账号");
    				form.user.focus();
    				return false;
    			}
    			if(form.pass.value==""){
    				alert("请输入密码");
    				form.pass.focus();
    				return false;
    			}
    			if(form.verify.value==""){
    				alert("请输入验证码");
    				form.verify.focus();
    				return false;
    			}
    		}
    	</script>
      </head>
      
      <body>
        
        <center>
        	<form action="verify.jsp" method="post" onSubmit="return check_admin(this);">
        		<table width="400" border="1" bordercolor="#99ccff" cellpadding="0" cellspacing="0" style="border-collapse: collapse;">
        			<tr>
        				<td height="40" colspan="2" align="center">
        				 <font>后台登录</font> 
        				</td>
        			</tr>
        			<tr>
        				<td height="40" align="right"> 账号: </td>
        				<td width="200" align="left" valign="middle">
        				    <input type="text" name="user" size="21" />
        				</td>    				
        			</tr>
        			<tr>
        				<td height="40" align="right"> 密码: </td>
        				<td width="40" align="left" valign="middle">
        				    <input type="password" name="pass" size="21" />
        				</td>
        			</tr>
        			<tr>
        				<td height="40" align="right"> 系统验证码: </td>
        				<td >
        				    <img border="0"   alt="系统验证码" src="verifyCode.jsp">
        				</td>
        			</tr>
        			<tr>
        				<td height="40" align="right"> 输入验证码: </td>
        				<td>
        				    <input type="text" name="verify" maxlength="4" size="21" value="" />
        				</td>
        			</tr>
        			<tr>    				
        				<td height="40" colspan="2" align="center">
        					<input type="submit" value="确定" />	 
        				    <input type="reset" value="重置" />
        				</td>
        			</tr>
        		</table>
        	</form>
        </center>
      </body>
    </html>

verify.jsp代码

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    
    
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
        
        
        <title>My JSP 'verify.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">
    
      </head>
      
      <body>
        <%
        	String rand =(String)session.getAttribute("rand");
        	String input =request.getParameter("verify");
        	String strUser=request.getParameter("user");
        	String strPass=request.getParameter("pass");
        	if(strUser.equals("admin")&&strPass.equals("admin")&&rand.equals(input)){
        		out.println("<h3>登陆成功</h3>");
        	}else{
        		out.println("<h3>登陆失败</h3>");
        	}
        	
        	
         %>
      </body>
    </html>

verifyCode.jsp代码

<%@ page contentType="image/jpeg"  language="java"  pageEncoding="utf-8"%>
    
    <%@ page import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*"%>
    
    <%!
    	Color getRandColor(int fc,int bc)
    	{        
            if(fc>255) fc=255;
            if(bc>255) bc=255;
            //随机生成rgb颜色
            Random random = new Random();
            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,22));
    
    //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),40+random.nextInt(110),60+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());
    %>

[20180520113528555]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/9904de3cb33c42e488ddbd572555c941.png
[20180520113613133]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/b25997aba99c4c6d86fff10ed7bd1fbb.png