验证码的使用

转载本人163博客，因工作时间只能访问技术站

http://chaoji-liangbin.blog.163.com/blog/static/252392122010102952243278/

往往验证码多处用到，所以写一个servlet即可，多处页面可以调用。具体如下：

index.jsp页面定义如下:

验证码：
<span onclick="refresh();"><img src="autoImg" id="autoImg" style="cursor: pointer;">
</span>

js代码：

<script type="text/javascript">
function refresh(){
document.getElementById("autoImg").src = 'autoImg?now=' + new Date();
}
</script>

web.xml定义：

<servlet>
<servlet-name>img</servlet-name>
<servlet-class>com.wenbin.example.AutoImg</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>img</servlet-name>
<url-pattern>/autoImg</url-pattern>
</servlet-mapping>

AutoImg.java 定义如下：

package com.wenbin.example;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;

p lic class AutoImg extends HttpServlet {
private Font mFont = new Font("Arial Black", Font.PLAIN, 16);

p lic void init() throws ServletException {
super.init();
}

Color getRandColor(int fc, int bc) {
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);
}

p lic void service(HttpServletReqst reqst, HttpServletResponse response)
throws ServletException, IOException {
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");

int width = 70, height = 18;
B?redImage image = new B?redImage(width, height,
B?redImage.TYPE_INT_RGB);

Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(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);
g.setFont(mFont);

g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g.drawLine(x, y, x + xl, y + yl);
}
for (int i = 0; i < 70; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(12) + 1;
int yl = random.nextInt(6) + 1;
g.drawLine(x, y, x - xl, y - yl);
}

String sRand = "";
for (int i = 0; i < 4; i++) {
String tmp = getRandomChar();
sRand += tmp;
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(tmp, 15 * i + 10, 15);
}

HttpSession session = reqst.getSession(tr);
session.setAttribute("rand", sRand);
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
}

private String getRandomChar() {
int rand = (int) Math.round(Math.random() * 2);
long itmp = 0;
char ctmp = '/';

/** 下方注释的代码为随机生成数字或字母 */
// switch (rand)
// {
// case 1:
// itmp = Math.round(Math.random() * 25 + 65);
// ctmp = (char)itmp;
// return String.valOf(ctmp);
// case 1:
// itmp = Math.round(Math.random() * 25 + 97);
// ctmp = (char)itmp;
// return String.valOf(ctmp);
// default :
// itmp = Math.round(Math.random() * 9);
// return String.valOf(itmp);
// }
/** 下方代码为随机生成数字 */
itmp = Math.round(Math.random() * 9);
return String.valOf(itmp);

}
}

验证码的获取：

对于sturts2而言，获取如下：

// HttpServletReqst reqst = ServletActionContext.getReqst (); //获取reqst
Map session=(Map)ActionContext.getContext().get(ActionContext.SESSION);
System.out.println("rand:"+session.get("rand"));

对于普通的jsp：

直接session.getAttribute("rand");

就可以了

OK，访问页面出现验证码，点击图片，自动刷新。