JSP驗證碼代碼

最後更新：2018-12-05 來源：互聯網

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產生有4個隨機數字和雜亂背景的圖片，數字和背景顏色會改變，伺服器端重新整理（用history.go(-1)也會變）
原型參考ALIBABA http://china.alibaba.com/member/showimage

產生驗證碼圖片的檔案-----image.jsp

    <%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
    <%!
    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);
            }
    %>
    <%
    //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("Times New Roman",Font.PLAIN,18));

    //畫邊框
    //g.setColor(new Color());
    //g.drawRect(0,0,width-1,height-1);

    // 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(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());

---------------使用驗證碼圖片的檔案---------a.jsp------------------------------------

    <%@ page contentType="text/html;charset=gb2312" %>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
    <head>
    <title>認證碼輸入頁面</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>系統產生的認證碼：</td>
    <td><img border=0 src="image.jsp"></td>
    </tr>
    <tr>
    <td align=left>輸入上面的認證碼：</td>
    <td><input type=text name=rand maxlength=4 value=""></td>
    </tr>
    <tr>
    <td colspan=2 align=center><input type=submit value="提交檢測"></td>
    </tr>
    </form>
    </body>
    </html>

-----------------驗證的頁面----------check.jsp

    <%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
    <html>
    <head>
    <title>認證碼驗證頁面</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");
    %>
    系統產生的認證碼為： <%= rand %><br>
    您輸入的認證碼為： <%= input %><br>
    <br>
    <%
      if (rand.equals(input)) {
    %>
    <font color=green>輸入相同，認證成功！</font>
    <%
      } else {
    %>
    <font color=red>輸入不同，認證失敗！</font>
    <%
      }
    %>
    </body>
    </html>

本文章原先以中文撰寫並發佈於 aliyun.com，亦設英文版本，僅作資訊用途。本網站不對文章的準確性，完整性或可靠性或其任何翻譯作出任何明示或暗示的陳述或保證。如對該文章有任何疑慮或投訴，請傳送電郵至 info-contact@alibabacloud.com 並提供相關疑慮或投訴的詳細說明。職員會於 5 個工作天內與您聯絡，一經驗證之後，即會刪除該侵權內容。

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