Servlet验证码的创建应用

来源：互联网发布：如何建设网络强国编辑：程序博客网时间：2024/06/07 03:47

1. 打开javaEE，新建一个Dynamic Web Project,然后在工程下的Java Resources—src新建一个Servlet

@WebServlet("/ImgResponse")

publicclass ImgResponseextends HttpServlet {

privatestaticfinallongserialVersionUID = 1L;

public ImgResponse() {

super();

//TODO Auto-generated constructor stub

}

protected void doGet(HttpServletRequestrequest,HttpServletResponseresponse)throws ServletException, IOException {

this.doPost(request,response);

}

protected void doPost(HttpServletRequestrequest,HttpServletResponseresponse)throws ServletException, IOException {

//设置响应类型

response.setContentType("image/jpeg");

//阻止页面被缓存，保证每次生成新的验证码

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

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

response.setIntHeader("Expires", 0);

//设置验证码图形的大小

intwidth = 100;

intheight = 18;

//生成一张新图片

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

//绘图

Graphics g =image.getGraphics();

g.setFont(new Font("ArialBlack", Font.PLAIN, 16));

g.setXORMode(Color.BLACK);

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

g.fillRect(1, 1, width - 1,height - 1);

g.setColor(new Color(102, 102, 102));

g.drawRect(0, 0, width - 1,height - 1);

//绘制一些随机线条，让画面显得更凌乱

Random r =new Random();

g.setColor(getRandomColor(160, 200));

for (inti = 0;i < 155; i++) {

intx0 =r.nextInt(width) - 1;

inty0 =r.nextInt(height) - 1;

intx1 =r.nextInt(12) + 1;

inty1 =r.nextInt(6) + 1;

g.drawLine(x0,y0,x0 +x1,y0 +y1);

}

for (inti = 0;i < 70; i++) {

intx0 =r.nextInt(width) - 1;

inty0 =r.nextInt(height) - 1;

intx1 =r.nextInt(12) + 1;

inty1 =r.nextInt(6) + 1;

g.drawLine(x0,y0,x0 -x1,y0 -y1);

}

//绘制验证码

intsize = 6;

//取得一个6位的随机验证码

String randomString = getRandomString(size);

//绘制验证码

for (inti = 0;i < size;i++) {

g.setColor(new Color(100 +r.nextInt(110), 100 +r.nextInt(110),

100 + r.nextInt(110)));

g.drawString(randomString.substring(i,i + 1), i * 15 + 10, 15);

}

g.dispose();

//将验证码发给浏览器

ImageIO.write(image,"JPEG",response.getOutputStream());

}

/**

* 产生一个随机的颜色

* 注意这个颜色不能漫无边际的产生，否则验证码一点也看不清

private Color getRandomColor(intfc,intbc) {

if (fc > 255)

fc = 255;

if (bc > 255)

bc = 255;

Random r =new Random();

intred =r.nextInt(bc -fc);

intgreen =r.nextInt(bc -fc);

intblue =r.nextInt(bc -fc);

returnnew Color(red,green,blue);

}

/**

* @param size

* 随机字符串的长度

* @return随机字符串

private String getRandomString(intsize) {

StringBuilder builder =new StringBuilder();

Random r =new Random();

intcount = 0;

while (count <size) {

inttemp =r.nextInt('z' + 1);

if ((temp >='A' && temp <= 'Z') || (temp >='a' &&temp <= 'z')

|| (temp >='0' &&temp <= '9')) {

builder.append((char)temp);

count++;

}

returnbuilder.toString();

}

2、在WebContent下新建一个jsp文件

<%@ page language="java"contentType="text/html; charset=utf-8"pageEncoding="utf-8"%>

<!DOCTYPE htmlPUBLIC"-//W3C//DTDHTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert titlehere</title>

function change(){

document.getElementById("image").src="ImgResponse?now="+new Date();

}

</script>

</head>

<body>

<form>

用户名：<inputtype="text"name="username"><br>

密码：<inputtype="password"name="password"><br>

验证码：<inputtype="text"name="code"><imgid="image"src="ImgResponse"/>

</form>

</body>

</html>

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