带有校验码的登陆实现（二）-优快云博客

本文介绍了一个简单的登录页面设计，包括用户名、密码输入及验证码功能。通过Java Servlet生成随机验证码图片，并利用JavaScript进行表单验证。

简单实现　

<%@ page language="java" contentType="text/html; charset=gb2312"%>
<html>
<head>
<title>login verfiy code</title>
</head>

<tr>
  <td>密码：</td>
  <td><input type="password" name="password"></td>
</tr>
<tr>
  <td>校验码</td>
  <td><input type="text" name="verfyCode">
  <td>
  <td><img id="image1" src="<%="login"%>"> <input
   type="button" value="更换一张" onclick="chage();"></td>
</tr>
</table>
<input type="button" value="确定" onclick="mysubmit();"></center>
</form>
<script language="javascript">
function chage(){
var l = Math.random()
var str = "<%=request.getContextPath()+"/"+"login"%>";
str = str+"?"+l;
document.getElementById('image1').src = str;
}

实现图片的servlet

package com.hundsun.imagverify;

import java.awt.image.BufferedImage;
import java.io.IOException;

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;

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

public class AuthorizationCodeImg extends HttpServlet {

/**
*
*/
private static final long serialVersionUID = 5530175206951266696L;

// Initialize global variables
public void init() throws ServletException {
}
// Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  HttpSession session = request.getSession();
  response.setContentType("image/jpeg");
  CreateImage createImg = new CreateImage();
  ServletOutputStream out = response.getOutputStream();
  BufferedImage image = createImg.createImg(4);
  JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
  encoder.encode(image);
  out.close();
  String code = createImg.sRand;
     session.setAttribute("code", code);
}
// Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doGet(request, response);
}
public void destroy() {
}
}

实现图片效果类

package com.hundsun.imagverify;

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

public class CreateImage {

public static String sRand = "";

/**
* Get Random Color
*
* @param fc
* @param bc
* @return Color
*/

public 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);
}

/**
* Create a image
*
* @param size
* @return image
*/
public BufferedImage createImg(int size) {
  // 在内存中创建图象
  // int width=60, height=20;
  int width = 12 * size, 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100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 < 100; 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(size位字符串)
  String rand = new CreateRandomString().getRandomString(size);
  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, 6, 16);

// 图象生效
g.dispose();

return image;
}
}

生成随机字符串

public class CreateRandomString {
public CreateRandomString() {
}
/**
* Get String Created by Random Function
*
* @param size
* @return String
*/
public String getRandomString(int size) {
  String str = "1234567890";
  Random random = new Random(); // 初始化随机数产生器
  StringBuffer sb = new StringBuffer();
  for (int i = 0; i < size; i++) {
   sb.append(Math.abs(random.nextInt())%str.length());
  }
  return sb.toString();
}

}