jsp 实现验证码

一.新建image.jsp文件

<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>

<%@ page import="java.io.OutputStream"%>

<%!Color getRandColor(int fc, int bc) {

Random random = new Random();

if (fc > 255)

fc = 255;

if (bc > 255)

bc = 255;

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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);

}%>

<%

try {

response.setHeader("Pragma", "No-cache");

response.setHeader("Cache-Control", "no-cache");

response.setDateHeader("Expires", 0);

int width = 60, height = 20;

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

OutputStream os = response.getOutputStream();

Graphics g = image.getGraphics();

Random random = new Random();

g.setColor(getRandColor(200, 250));

g.fillRect(0, 0, width, height);

g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

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);

}

String sRand = "";

for (int i = 0; i < 4; i++) {

String rand = String.valueOf(random.nextInt(10));

sRand += rand;

g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));

g.drawString(rand, 13 * i + 6, 16);

}

System.out.println(sRand);

session.setAttribute("rand", sRand);

g.dispose();

ImageIO.write(image, "JPEG", os);

os.flush();

os.close();

os = null;

response.flushBuffer();

out.clear();

out = pageContext.pushBody();

} catch (IllegalStateException e) {

System.out.println(e.getMessage());

e.printStackTrace();

}

%>

二.在需要引入的地方

<tr style="height: 22px">

<td>

<font color="#FFFFFF">验证码：</font>

</td>

<td  width="200">

<input id="codeInputFront"  class="inputText" type="text" style="width: 50px" />

<img id="LoginImgVerifyCode" style="float: left; src="jsp/frontstage/index/image.jsp" />

<a href="javascript:changeVerifyCode()">刷新</a>

</td>

</tr>

注意：<image>标签中要写相对路径。但是一定是写全，基于WebRoot 目录下方