JSP之验证码登陆(用JAVA绘制验证码)

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

<!--设置页面类型和编码  -->
<%@ page contentType="image/jpeg"  language="java"  pageEncoding="utf-8"%>
<!--导入需要的包 -->
<%@ page import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*"%>
<!--给定范围获得随机颜色 -->
<%!
	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());
%>

JSP之验证码登陆(用JAVA绘制验证码)

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