servlet中生成验证码

在servlet中生成验证码

package login;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.OutputStream;

import java.io.PrintWriter;

import java.util.Random;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import com.sun.image.codec.jpeg.JPEGCodec;

import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**

* 生成验证码servlet

* @author Administrator

*

*/

public class CheckCodeServlet extends HttpServlet {

public void service(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

System.out.println("service called");

/**1.设置服务器响应类型为jpg格式图片 */

response.setContentType("image/jpeg");

/**2.画图**/

//1.在内存中开辟空间存储图片

BufferedImage image = new BufferedImage(60,25,BufferedImage.TYPE_INT_RGB);

//2.获得画笔

Graphics g = image.getGraphics();

//3.准备随机数对象

Random r = new Random();

//4.设置图片背景色

g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255)));

//5.填充

g.fillRect(0, 0, 60, 25);

//6.设置画笔前景色(设置字体颜色)

g.setColor(new Color(0,0,0));

//7.产生随机数

String number = String.valueOf(r.nextInt(99999)+1000);

/**将验证码存放session中*/

HttpSession session =request.getSession();

session.setAttribute("checkcode", number);

//8.数字画到图片上

g.drawString(number, 15,15);

g.drawLine(r.nextInt(20), r.nextInt(20), r.nextInt(50), r.nextInt(50));

g.drawLine(r.nextInt(20), r.nextInt(20), r.nextInt(50), r.nextInt(50));

g.drawLine(r.nextInt(20), r.nextInt(20), r.nextInt(50), r.nextInt(50));

g.drawLine(r.nextInt(20), r.nextInt(20), r.nextInt(50), r.nextInt(50));

/**3.使用特定格式压缩图片并输出*/

//1.建立文件输出流

OutputStream os =response.getOutputStream();

//2.使用指定格式

JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(os);

encoder.encode(image);

}

}

在jsp页面使用java产生的验证码：

<td style="width:80px">

验证码:

</td>

<td valign="middle" >

<input name="validatecode" size="7px"/>

<img src="checkcode" id="img"><!-- 等效于"#" -->

<a href="javascript:;" onclick="document.getElementById(‘img‘).

src=‘checkcode?‘+new Date().getTime();"><span style="font-size:12px;">看不清，换一张</span></a>

<br/>

<span style="color:red;">

<%

String check_error=(String)request.getAttribute("check_error");

%>

<%=check_error==null?"":check_error%>

</span>

</td>

在xmd文件里面的配置

<servlet>

<servlet-name>check</servlet-name>

<servlet-class>login.CheckCodeServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>check</servlet-name>

<url-pattern>/checkcode</url-pattern>

</servlet-mapping>

进行验证判断的部分代码：

String validatecode=request.getParameter("validatecode");//验证码

String checkCode=(String)session.getAttribute("checkcode");

在servlet里面进行比较

servlet中生成验证码,布布扣,bubuko.com