response生成图片验证码

最新推荐文章于 2022-08-30 15:59:10 发布

learnjavaluojing

最新推荐文章于 2022-08-30 15:59:10 发布

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分类专栏： servlet 文章标签： Servlet Java SUN JSP XML

本文链接：https://blog.youkuaiyun.com/learnjavaluojing/article/details/83672758

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本文介绍了一种简单的验证码生成方法，通过Java Servlet实现自定义验证码图片，并在网页上展示。该方法利用随机字符和颜色提高安全性，同时提供了刷新验证码的功能。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

感觉生成出来的效果还不错，比较简单，直接在servlet里生成验证码图片，然后在页面上显示，不过还是记下来收藏下，或许以后会有得着地方，也希望能给博友们提供一个引用的方便。
代码如下：Indentity 类
package com.luojing.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
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 Indentity extends HttpServlet {

public static final char[] CHARS ={'2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z'};

public static Random random = new Random();

public static String getRandomString(){//创建随机字符

StringBuffer buffer = new StringBuffer();

for(int i=0;i<5;i++){ //随机循环输出5个字符

buffer.append(CHARS[random.nextInt(CHARS.length)]);

}
return buffer.toString();
}
public static Color getRandomColor(){ //创建随机颜色

return new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255));
}
public static Color getReverseColor(Color c){//创建随机的反色颜色

return new Color(255-c.getRed(),255-c.getGreen(),255-c.getBlue());
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

response.setContentType("image/jpeg");//设置输出类型

String randomString = getRandomString();

request.getSession().setAttribute("randomString", randomString);//放入session中

int width=100;

int height=30;

Color color = getRandomColor();//随机颜色，用于背景色

Color reverse = getReverseColor(color);//反色，用于前景色

BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);//创建一个彩色图片

Graphics2D g = bi.createGraphics();//获取绘图对象

g.setFont(new Font("方正舒体",Font.BOLD,18));

g.setColor(color);

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);//随机噪音点
}

ServletOutputStream out = response.getOutputStream();//转换成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

}
}

JSP页面显示：index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<script type="text/javascript">
function reloadimage(){
document.getElementById("btn").disabled=true;
document.getElementById("indentity").src='indentity.do?ts='+new Date().getTime();
}
</script>
<body>
<img src="indentity.do" id="indentity" onload="btn.disabled=false;"/>
<input type="button" value="看不清，换一张" onclick="reloadimage()" id="btn"/>
</body>
</html>
web.xml配置如下：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>Indentity</servlet-name>
<servlet-class>com.luojing.servlet.Indentity</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>Indentity</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>