jsp页面验证码完整实例


            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="http://java.sun.com/xml/ns/javaee" 

  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 

  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 

  http://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" "http://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" onload="btn.disabled=false;" />

<input type=button value="换个图片" onclick="reloadImage()" id="btn">

</body>

</html>





启动Tomcat，输入网址：http://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中文源码网。