jsp页面验证码完整实例

PHP小丑

本文实例为大家分享了sp页面验证码的具体代码，供大家参考，具体内容如下
项目结构如下，MyEclipse中新建一个Web Project，取名servlet

1、src下new一个servlet类

package com.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class IdentityServlet extends HttpServlet {
  public static final char[] chars={'2','3','4','5','6','7','8','9','A'};//自定义验证码池
  public static Random random=new Random();//随机数
  
  public static String getRandomString(){//获取6位随机数，放在图片里
  StringBuffer buffer=new StringBuffer();
  for(int i=0;i<6;i++){
    buffer.append(chars[random.nextInt(chars.length)]);
  }
  return buffer.toString();
  }
  
  public static Color getRandomColor(){//获取随机的颜色
  return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
  }
  
  public static Color getReverseColor(Color c){//返回某颜色的反色
  return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());
  }
  
  /**
   * Constructor of the object.
   */
  public IdentityServlet() {
  super();
  }
  /**
   * Destruction of the servlet. <br>
   */
  public void destroy() {
  super.destroy(); // Just puts "destroy" string in log
  // Put your code here
  }
  /**
   * The doGet method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to get.
   * 
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
  public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
  response.setContentType("image/jpeg");//设置输出类型
  
  String randomString = getRandomString();//随机字符串
  request.getSession(true).setAttribute("randomString", randomString);//放到session里
  
  int width=100;//图片宽度
  int height=30;//图片高度
  
  Color color=getRandomColor();//随机颜色，用于背景色
  Color reverse=getReverseColor(color);//反色，用于前景色
  //创建一个彩色图片
  BufferedImage bi=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
  Graphics2D g=bi.createGraphics();//绘图对象
  g.setFont(new Font(Font.SANS_SERIF,Font.BOLD,16));//设置字体
  g.setColor(color);//设置颜色
  g.fillRect(0, 0, width, height);//绘制背景
  g.setColor(reverse);
  g.drawString(randomString, 18, 20);//绘制随机字符
  for(int i=0,n=random.nextInt(100);i<n;i++){//画最多100个噪音点
    g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
  }
  ServletOutputStream out= response.getOutputStream();//转成JPEG格式
  JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);//编码器
  encoder.encode(bi);//对图片进行编码
  out.flush();//输出到客户端
  }
  /**
   * The doPost method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to post.
   * 
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
  public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
  doGet(request, response);
  }
  /**
   * Initialization of the servlet. <br>
   *
   * @throws ServletException if an error occurs
   */
  public void init() throws ServletException {
  // Put your code here
  }
}

2、web.xml，会自动生成servlet和servlet-mapping的配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
  xmlns="https://java.sun.com/xml/ns/javaee" 
  xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" 
  xsi:schemaLocation="https://java.sun.com/xml/ns/javaee 
  https://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
 <display-name></display-name>
 <servlet>
  <servlet-name>IdentityServlet</servlet-name>
  <servlet-class>com.servlet.IdentityServlet</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>IdentityServlet</servlet-name>
  <url-pattern>/servlet/IdentityServlet</url-pattern>
 </servlet-mapping>  
 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>

3、WebRoot下新建一个html，展示验证码

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "https://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
function reloadImage(){
  document.getElementById('btn').disabled=true;
  document.getElementById('identity').src='servlet/IdentityServlet?ts='+new Date().getTime();
}
</script>
</head>
<body>
<img src="servlet/IdentityServlet" id="identity"  />
<input type=button value="换个图片"  id="btn">
</body>
</html>

启动Tomcat，输入网址：https://localhost:8080/servlet/identity.html，效果如下：

点击‘换个图片'，会生成新的验证码。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持CodeAE代码之家。