实现验证码

最新推荐文章于 2024-11-02 11:53:18 发布

willvc123

最新推荐文章于 2024-11-02 11:53:18 发布

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文章标签： servlet random string image initialization class

本文链接：https://blog.youkuaiyun.com/willvc123/article/details/3901020

写一个生产图片的servelt

package com.index.common;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Image extends HttpServlet {

/**
* Constructor of the object.
*/
public Image() {
super();
}

/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}

/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occure
*/
public void init() throws ServletException {
// Put your code here
}
/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
HttpSession session=request.getSession();
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取图形上下文
Graphics g = image.getGraphics();

// 生成随机类
Random random = new Random();

// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

// 设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));

// 画边框
// g.setColor(new Color());
// g.drawRect(0,0,width-1,height-1);

// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
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);
}

// 取随机产生的认证码(4位数字)
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// 将认证码显示到图象中
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand,13*i+6,16);
}

// 将认证码存入SESSION
session.setAttribute("rand",sRand);
// 图象生效
g.dispose();
ServletOutputStream responseOutputStream =response.getOutputStream();
// 输出图象到页面
ImageIO.write(image, "JPEG", responseOutputStream);

// 以下关闭输入流！
responseOutputStream.flush();
responseOutputStream.close();
}
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
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);
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/** Handles the HTTP <code>GET</code> method.
* @param request servlet request
* @param response servlet response
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}

/** Handles the HTTP <code>POST</code> method.
* @param request servlet request
* @param response servlet response
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}

/** Returns a short description of the servlet.
*/
public String getServletInfo() {
return "Short description";
}

}

在web.xml 配置一下

<servlet-mapping>
<servlet-name>Image</servlet-name>
<url-pattern>/Image</url-pattern>
</servlet-mapping>

在页面调用

<tr>
           <td>
            <div align="left">
             <span class="style2">验证码：</span>
            </div>
           </td>
           <td>
            <span class="zi1"> <img border=0 src="<%=path %>/Image">
            </span>
           </td>
          </tr>
          <tr>
           <td>
            <div align="left">
             <span class="style2">输入验证码</span>
            </div>
           </td>
           <td>
            <span class="zi1"> <input type=text name=rand
              maxlength=4 value=""> </span>
           </td>
          </tr>