生成有4個隨機數字和雜亂背景的圖片，數字和背景顏色會改變，服務器端刷新（用history.go(-1)也會變）
產生驗證碼圖片的文件image.jsp
| <%@ page contenttype="image/jpeg" import="java.awt.*, java.awt.image.*,java.util.*,javax.imageio.*" %> <%! color getrandcolor(int fc,int bc){//給定范圍獲得隨機顏色 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); } %> <% //設置頁面不緩存 response.setheader("pragma","no-cache"); response.setheader("cache-control","no-cache"); response.setdateheader("expires", 0); // 在內存中創建圖象 int width=60, height=20; bufferedimage image = new bufferedimage(width, height, bufferedimage.type_int_rgb); // 獲取圖形上下文 graphics g = image.getgraphics(); //生成隨機類 random random = new random(); // 設定背景色 g.setcolor(getrandcolor(200,250)); g.fillrect(0, 0, width, height); //設定字體 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條干擾線，使圖象中的認證碼不易被其它程序探測到 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位數字) 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，所以只能直接生成 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()); %> |
| <%@ 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> |
| <%@ 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?。?lt;/font> <% } %> </body> </html> |
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