jsp 登陸驗證碼

最後更新：2018-12-05 來源：互聯網

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image.jsp

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<%@ page language="java" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" 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 'images.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>
   <%!
Color getRandColor(int fc,int bc){//給定範圍獲得隨機顏色
        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);
        }
%>
<%
out.clear();
//設定頁面不緩衝
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);

// 在記憶體中建立圖象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 擷取圖形上下文
Graphics g = image.getGraphics();

//產生隨機類
Random random = new Random();

// 設定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

//設定字型
g.setFont(new Font("Comic Sans MS",Font.PLAIN,18));

// 隨機產生155條幹擾線，使圖象中的認證碼不易被其它程式探測到
g.setColor(getRandColor(220,240));
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);
}

// 取隨機產生的認證碼(4位元字)
String sRand="";
for (int i=0;i<4;i++){
    String rand=String.valueOf(random.nextInt(10));
    sRand+=rand;
    // 將認證碼顯示到圖象中
    g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
//調用函數出來的顏色相同，可能是因為種子太接近，所以只能直接產生
    g.drawString(rand,13*i+6,16);
}

// 將認證碼存入SESSION
session.setAttribute("rand",sRand);

// 圖象生效
g.dispose();

// 輸出圖象到頁面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>

</body>
</html>

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

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

function loadimage(){
document.getElementById("randImage").src = "images.jsp?"+Math.random();
}

               <c:if test="${imageResult==1}">
              <span class="STYLE1"><font color="red">驗證碼錯誤，請重新輸入。</font> </span>
              </c:if>

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

ksuserAction.java

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

String rand = request.getParameter("rand");
String imageRand = (String)request.getSession().getAttribute("rand");

if(rand.equals(imageRand)){
    imageResult = -1;
    return Default();
   }else{
    imageResult = 1;
    return Login();
   }

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