標籤：jsp java 驗證碼 登陸 代碼
填寫輸入資訊index.jsp<html><body>
<formmethod=postaction="result.jsp">
<inputtype=textname=inputmaxlength=4>
<imgborder=0src="image.jsp">
<inputtype="submit"value="submit">
</form></body></html>
產生圖片image.jsp<%@ page contentType="image/JPEG"
import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"
pageEncoding="GBK"%>
<%!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(newColor());
//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 < 100; 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("code",sRand);
// 圖象生效
g.dispose();
// 輸出圖象到頁面
ImageIO.write(image, "JPEG",response.getOutputStream());
%>
驗證是否輸入正確result.jsp<%@ page language="java"import="java.util.*"pageEncoding="GBK"%>
<html><body>
<%
String input=request.getParameter("input");
String code=(String)session.getAttribute("code");
if(input.equals(code)){
out.println("驗證成功!");
}else{
out.println("驗證失敗!");
}
%>
</body></html>
可能遇到的問題：你的eclipse會提示你：graphic.drawString()方法錯誤
是你的jdk版本太高了，但是不要緊。把這個項目的相容版本放低就行了。
具體操作步驟：
右鍵過程，選中propriety，再選中“Java compiler”
把jdk的相容版本降低到1.4即可
jsp實現登陸驗證碼
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