验证码的制作
【制作验证码】
web.xml配置为：
<!-- com.gdy.xiazai.getimage 类的创建 -->
<servlet>
<servlet-name>gimg</servlet-name>
<servlet-class>com.gdy.xiazai.getimage</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>gimg</servlet-name>
<url-pattern>*.gimg</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>login.html</welcome-file>
</welcome-file-list>
后台java代码为：
package com.gdy.xiazai;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 【*。gimg】请求处理类
* 功能：
* 制作验证码
* @author Administrator
*
*/
public class getimage extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// getimg(req,resp);
outputYZM(req, resp);
}
/**
* 验证码的制作
* @param req
* @param resp
*/
protected void outputYZM(HttpServletRequest req, HttpServletResponse resp){
int width=100;
int height=20;
//创建缓存图像
BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
//创建画笔
Graphics grap=image.getGraphics();
//指定边框颜色
grap.setColor(Color.RED);
//画图像边框
grap.drawRect(0, 0, width, height);
//填充一下矩形的背景颜色
//设定画笔的颜色
grap.setColor(Color.YELLOW);
//填充矩形背景
grap.fillRect(1, 1, width-2, height-2);
//填充内容
//设置画笔的颜色
grap.setColor(Color.BLACK);
String str="Android训练营";
//随机产生4个数字输出到页面
Random r=new Random();
for(int i=0;i<4;i++){
//产生随机数字
// int n= r.nextInt(10);
// grap.drawString(n+"", ((width-2)/5)*(i+1), 16);
int flag=r.nextBoolean()?1:-1;
//设置随机大小的字体
grap.setFont(new Font("幼圆",Font.BOLD + Font.ITALIC,20+flag*r.nextInt(10)));
//产生随机字符
grap.drawString(str.charAt(r.nextInt(str.length()))+"", ((width-2)/5)*(i+1)+flag*r.nextInt(6), 14+r.nextInt(4)*flag);
}
//设置干扰线
grap.setColor(Color.GRAY);
//画30条干扰线
for(int i=0;i<r.nextInt(30);i++){
grap.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));
}
//将图片输出到客户端
try {
//告诉客户端不要缓存图像
resp.setHeader("Expires", -1+"");
resp.setHeader("Cache-control", "no-cache");
resp.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpg", resp.getOutputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
<!DOCTYPE html>
<html>
<head>
<title>MyHtml.html</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<table>
<tr>
<td>姓名：</td>
<td><input type="text"></td>
</tr>
<tr>
<td>年龄：</td>
<td><input type="text"></td>
</tr>
<tr>
<td><input type="text"></td>
<td>验证码：<img id="id_yzm" src="/T20160419/a.gimg" onclick="change()" /><a href="javascript:change()" >看不起， 换一张</a></td>
<script type="text/javascript">
function change(){
//alert("aa");
var yzm=document.getElementById("id_yzm");
//加一个无意义的参数，让地址每次都变化
yzm.src="/T20160419/a.gimg?t="+new Date().getTime();
}
</script>
</tr>
<tr>
<td></td>
<td><input type="submit" value="提交"></td>
</tr>
</table>
</body>
</html>
效果图如下：
