java图片验证码,java图片验证码登录

发布时间:2023-01-09

本文目录一览:

  1. java验证码怎么实现让图片中的文字旋转30°
  2. 用java怎么制作验证码
  3. Java如何实现验证码验证功能
  4. JAVA识别图片验证码
  5. 如何用Java代码段生成四位数字加字母的验证码?
  6. 怎么用Java代码实现一个验证码,求具体实现方法

java验证码怎么实现让图片中的文字旋转30°

  1. 在图形验证码程序的生成过程中(一般中servlet中生成),使用session.setAttribute("code",yourcode);
  2. 在jsp页面接收是用session.getAttribute("code")即可 希望能够帮到你, 如若你有不清楚的,欢迎探讨。 淘宝会员:宜人家园

用java怎么制作验证码

原理:

  1. 随机生成4个数字,用到了Random
  2. 对这4个数字设置字体格式,用setFont方法
  3. 改变字体颜色用setColor,然后随机生成颜色 代码如下
package s1;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.jms.Session;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class GetImage extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 发送图片不能够添加这2行代码
        // response.setContentType("text/html;charset=UTF-8");
        // request.setCharacterEncoding("UTF-8");
        int width = 100;
        int height = 50;
        // 获得一张图片
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        g.setColor(Color.WHITE);
        g.fillRect(1, 1, width - 2, height - 2);
        g.setFont(new Font("宋体", Font.BOLD, 30));
        Random random = new Random();
        // 填充的字符串
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        // 缓存生成的验证码
        StringBuffer stringbuffer = new StringBuffer();
        // 随机生成验证码的颜色和字符
        for (int i = 0; i < 4; i++) {
            // 设置随机颜色
            g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
            int index = random.nextInt(62); // 这里的62就是从填充字符段中随意选取一个位置
            String str1 = str.substring(index, index + 1);
            g.drawString(str1, 20 * i, 30); // x,y数值设置太小会显示不出来
            stringbuffer.append(str1);
        }
        // 将生成的验证码存到服务器
        request.getSession().setAttribute("checkcode", stringbuffer.toString()); // key和value
        // 将图片发送给浏览器
        ImageIO.write(image, "jpg", response.getOutputStream());
    }
}

用户登录界面代码

package s1;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class Login extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8"); // 设置服务器发送给浏览器的编码方式
        request.setCharacterEncoding("UTF-8"); // 客户端向服务器提交的数据的解码方式
        // 获得用户提交的数据
        String checkcode = request.getParameter("checkcode");
        System.out.println(checkcode);
        // 判断输入的验证码是不是符合
        HttpSession session = request.getSession(); // session是存放数据的地方
        String str = (String) session.getAttribute("checkcode");
        if (str != null) {
            if (checkcode.compareToIgnoreCase(str) == 0) // 验证码忽略大小写
                response.getWriter().println("验证码输入正确");
            else
                response.getWriter().println("验证码输入错误");
        } else
            response.getWriter().println("验证码失效");
        // 使用完的验证码信息要删除,返回原页面再输一次,验证码就失效了
        session.removeAttribute("checkcode");
    }
}

Java如何实现验证码验证功能

Java如何实现验证码验证功能呢?日常生活中,验证码随处可见,他可以在一定程度上保护账号安全,那么他是怎么实现的呢? Java实现验证码验证功能其实非常简单:用到了一个Graphics类在画板上绘制字母,随机选取一定数量的字母随机生成,然后在画板上随机生成几条干扰线。 首先,写一个验证码生成帮助类,用来绘制随机字母:

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
public final class GraphicHelper {
    /**
     * 以字符串形式返回生成的验证码,同时输出一个图片
     *
     * @param width
     *            图片的宽度
     * @param height
     *            图片的高度
     * @param imgType
     *            图片的类型
     * @param output
     *            图片的输出流(图片将输出到这个流中)
     * @return 返回所生成的验证码(字符串)
     */
    public static String create(final int width, final int height, final String imgType, OutputStream output) {
        StringBuffer sb = new StringBuffer();
        Random random = new Random();
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics graphic = image.getGraphics();
        graphic.setColor(Color.getColor("F8F8F8"));
        graphic.fillRect(0, 0, width, height);
        Color[] colors = new Color[] { Color.BLUE, Color.GRAY, Color.GREEN, Color.RED, Color.BLACK, Color.ORANGE,
                Color.CYAN };
        // 在 "画板"上生成干扰线条 (50 是线条个数)
        for (int i = 0; i < 50; i++) {
            graphic.setColor(colors[random.nextInt(colors.length)]);
            final int x = random.nextInt(width);
            final int y = random.nextInt(height);
            final int w = random.nextInt(20);
            final int h = random.nextInt(20);
            final int signA = random.nextBoolean() ? 1 : -1;
            final int signB = random.nextBoolean() ? 1 : -1;
            graphic.drawLine(x, y, x + w * signA, y + h * signB);
        }
        // 在 "画板"上绘制字母
        graphic.setFont(new Font("Comic Sans MS", Font.BOLD, 30));
        for (int i = 0; i < 6; i++) {
            final int temp = random.nextInt(26) + 97;
            String s = String.valueOf((char) temp);
            sb.append(s);
            graphic.setColor(colors[random.nextInt(colors.length)]);
            graphic.drawString(s, i * (width / 6), height - (height / 3));
        }
        graphic.dispose();
        try {
            ImageIO.write(image, imgType, output);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return sb.toString();
    }
}

接着,创建一个servlet,用来固定图片大小,以及处理验证码的使用场景,以及捕获页面生成的验证码(捕获到的二维码与用户输入的验证码一致才能通过)。

import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@WebServlet(urlPatterns = "/verify/regist.do")
public class VerifyCodeServlet extends HttpServlet {
    private static final long serialVersionUID = 3398560501558431737L;
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 获得 当前请求 对应的 会话对象
        HttpSession session = request.getSession();
        // 从请求中获得 URI (统一资源标识符)
        String uri = request.getRequestURI();
        System.out.println("hello : " + uri);
        final int width = 180; // 图片宽度
        final int height = 40; // 图片高度
        final String imgType = "jpeg"; // 指定图片格式 (不是指MIME类型)
        final OutputStream output = response.getOutputStream(); // 获得可以向客户端返回图片的输出流
        // (字节流)
        // 创建验证码图片并返回图片上的字符串
        String code = GraphicHelper.create(width, height, imgType, output);
        System.out.println("验证码内容: " + code);
        // 建立 uri 和 相应的 验证码 的关联 (存储到当前会话对象的属性中)
        session.setAttribute(uri, code);
        System.out.println(session.getAttribute(uri));
    }
}

接着写一个HTML注册页面用来检验一下:

<html>
<head>
<meta charset="UTF-8" />
<title>注册</title>
<link rel="stylesheet" href="styles/general.css" />
<link rel="stylesheet" href="styles/cell.css" />
<link rel="stylesheet" href="styles/form.css" />
<script type="text/javascript" src="js/ref.js"></script>
<style type="text/css">
.logo-container {
    margin-top: 50px;
}
.logo-container img {
    width: 100px;
}
.message-container {
    height: 80px;
}
.link-container {
    height: 40px;
    line-height: 40px;
}
.link-container a {
    text-decoration: none;
}
</style>
</head>
<body>
    <div class="container form-container">
        <form action="/wendao/regist.do" method="post">
            <div class="form">
                <!-- 注册表单开始 -->
                <div class="form-row">
                    <span class="cell-1">
                        <i class="fa fa-user"></i>
                    </span>
                    <span class="cell-11" style="text-align: left;">
                        <input type="text" name="username" placeholder="请输入用户名" />
                    </span>
                </div>
                <div class="form-row">
                    <span class="cell-1">
                        <i class="fa fa-key"></i>
                    </span>
                    <span class="cell-11" style="text-align: left;">
                        <input type="password" name="password" placeholder="请输入密码" />
                    </span>
                </div>
                <div class="form-row">
                    <span class="cell-1">
                        <i class="fa fa-keyboard-o"></i>
                    </span>
                    <span class="cell-11" style="text-align: left;">
                        <input type="password" name="confirm" placeholder="请确认密码" />
                    </span>
                </div>
                <div class="form-row">
                    <span class="cell-7">
                        <input type="text" name="verifyCode" placeholder="请输入验证码" />
                    </span>
                    <span class="cell-5" style="text-align: center;">
                        <img src="/demo/verify/regist.do" onclick="myRefersh(this)" />
                    </span>
                </div>
                <div class="form-row" style="border: none;">
                    <span class="cell-6" style="text-align: left">
                        <input type="reset" value="重置" />
                    </span>
                    <span class="cell-6" style="text-align: right;">
                        <input type="submit" value="注册" />
                    </span>
                </div>
            </div>
            <!-- 注册表单结束 -->
        </form>
    </div>
</body>
</html>

效果如下图: 在控制台接收到的图片中验证码的变化如下: 当点击刷新页面的时候,验证码也会随着变化,但我们看不清验证码时,只要点击验证码就会刷新,这样局部的刷新可以用JavaScript来实现。 在<img src="/demo/verify/regist.do"中,添加一个问号和一串后缀数字,当刷新时让后缀数字不断改变,那么形成的验证码也会不断变化,我们可以采用的一种办法是后缀数字用date代替,date获取本机时间,时间是随时变的,这样就保证了刷新验证码可以随时变化。 代码如下:

function myRefersh(e) {
    const source = e.src; // 获得原来的 src 中的内容
    var index = source.indexOf("?"); // 从 source 中寻找 ? 第一次出现的位置 (如果不存在则返回 -1)
    if (index > -1) { // 如果找到了 ? 就进入内部
        var s = source.substring(0, index); // 从 source 中截取 index 之前的内容 (index 以及 index 之后的内容都被舍弃)
        var date = new Date(); // 创建一个 Date 对象的实例
        var time = date.getTime(); // 从新创建的 Date 对象的实例中获得该时间对应毫秒值
        e.src = s + "?time=" + time; // 将加了尾巴的地址重新放入到 src 上
    } else {
        var date = new Date();
        e.src = source + "?time=" + date.getTime();
    }
}

如回答不详细可追问

JAVA识别图片验证码

package com.he;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.image.*;
import javax.imageio.*;
public class CodeFact extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 设置页面不缓存
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        // 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(33, 66, 99));
        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
        HttpSession session = request.getSession();
        session.setAttribute("rand", sRand);
        // 图象生效
        g.dispose();
        // 输出图象到页面
        ImageIO.write(image, "JPEG", response.getOutputStream());
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
    // 给定范围获得随机颜色
    private Color getRandColor(int fc, int bc) {
        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);
    }
}

你试试!!

如何用Java代码段生成四位数字加字母的验证码?

不知道你问的是不是生成这种图片验证码?如果只要一个随机四位数,那这行代码就够了(new Random().nextInt(9000) + 1000;),如果是生成页面图片验证码就是下面的了:

// 设定响应模式
resp.setContentType("image/jpeg");
// 生成令牌环数据
Integer token = new Random().nextInt(9000) + 1000;
// 保存令牌环数据到session中
req.getSession().setAttribute(IMAGE_TOKEN_NAME, token);
// 生成令牌环图片
ServletOutputStream out = resp.getOutputStream();
BufferedImage img = new BufferedImage(60, 20, BufferedImage.TYPE_INT_RGB);
Graphics g = img.getGraphics();
g.setColor(Color.YELLOW);
g.fillRect(0, 0, img.getWidth(), img.getHeight());
g.setColor(Color.BLUE);
g.setFont(new Font("", Font.BOLD, 18));
g.drawString(String.valueOf(token), 10, 16);
ImageIO.write(img, "jpg", out);
out.close();

下面简单的介绍他们的功能和用途,执行效率等。每个都有各自的优缺点看你是做甚什么方面的研究开发用。.net,是网站编程,现在很多都用这个,但是这个语言编程都有统一思路,很好掌握。窒息那个效率不是很高;php 支持跨平台,很容易学会,执行的效率很高;asp是ASP.net的前身,它比较稳定,比.net要弱一点。但是比.net好学。jsp 是网页编程,这个学习大约一周就能搞定,不过这个得多实践,不然的话,时间长了,就容易忘记。 我自己做的系统里面用作验证码的JSP的

<%@page contentType="image/jpeg;charset=utf-8"%>
<%@page import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*"%>
<%@ page import="java.io.OutputStream" %>
<html>
<body>
<%!
Color getRandColor(int fc,int bc) {
    Random rd=new Random();
    if(fc>255) fc=255;
    if(bc>255) bc=255;
    int red=fc+rd.nextInt(bc-fc);
    int green=fc+rd.nextInt(bc-fc);
    int blue=fc+rd.nextInt(bc-fc);
    return new Color(red,green,blue);
}
%>
<%
Random r=new Random();
response.addHeader("Pragma","No-cache");
response.addHeader("Cache-Control","no-cache");
response.addDateHeader("expires",0);
int width=90;
int height=23;
BufferedImage pic=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics gc=pic.getGraphics();
gc.setColor(getRandColor(200,250));
gc.fillRect(0,0,width,height);
String[] rNum ={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f",
    "g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w",
    "x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N",
    "O","P","Q","R","S","T","U","V","W","X","Y","Z"};
int[] style = {Font.PLAIN,Font.BOLD,Font.ITALIC,Font.PLAIN+Font.BOLD,
    Font.BOLD+Font.ITALIC,Font.PLAIN+Font.ITALIC,Font.PLAIN+Font.BOLD+Font.ITALIC};
gc.setColor(Color.WHITE);
gc.drawLine(0,30,90,10);
gc.setColor(getRandColor(160,200));
for (int i=0;i<50;i++) {
    int x = r.nextInt(width);
    int y = r.nextInt(height);
    int xl = r.nextInt(10);
    int yl = r.nextInt(10);
    gc.drawLine(x,y,x+xl,y+yl);
}
gc.setColor(getRandColor(60,150));
String rt = "";
for(int i=0;i<4;i++){
    String temp = rNum[r.nextInt(62)];
    rt = rt+temp;
    gc.setFont(new Font("Times New Roman",style[r.nextInt(7)],15));
    gc.drawString(temp,5+i*15+r.nextInt(10),10+r.nextInt(10));
}
gc.dispose();
session.setAttribute("randNum",rt);
OutputStream os=response.getOutputStream();
ImageIO.write(pic,"JPEG",os);
System.out.println("当前验证码为:"+session.getAttribute("randNum"));
os.flush();
os.close();
os=null;
response.flushBuffer();
out.clear();
out = pageContext.pushBody();
%>
</body>
</html>

怎么用Java代码实现一个验证码,求具体实现方法

package util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
public final class ImageUtil {
    // 验证码字符集
    private static final char[] chars = {
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
        'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
        'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
    };
    // 字符数量
    private static final int SIZE = 4;
    // 干扰线数量
    private static final int LINES = 5;
    // 宽度
    private static final int WIDTH = 80;
    // 高度
    private static final int HEIGHT = 40;
    // 字体大小
    private static final int FONT_SIZE = 30;
    /**
     * 生成随机验证码及图片
     * 返回的数组中,第1个值是验证码,第2个值是图片
     */
    public static Object[] createImage() {
        StringBuffer sb = new StringBuffer();
        // 1.创建空白图片
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        // 2.获取图片画笔
        Graphics graphic = image.getGraphics();
        // 3.设置画笔颜色
        graphic.setColor(Color.LIGHT_GRAY);
        // 4.绘制矩形背景
        graphic.fillRect(0, 0, WIDTH, HEIGHT);
        // 5.画随机字符
        Random ran = new Random();
        for (int i = 0; i < SIZE; i++) {
            // 取随机字符索引
            int n = ran.nextInt(chars.length);
            // 设置随机颜色
            graphic.setColor(getRandomColor());
            // 设置字体大小
            graphic.setFont(new Font(null, Font.BOLD + Font.ITALIC, FONT_SIZE));
            // 画字符
            graphic.drawString(chars[n] + "", i * WIDTH / SIZE, HEIGHT / 2);
            // 记录字符
            sb.append(chars[n]);
        }
        // 6.画干扰线
        for (int i = 0; i < LINES; i++) {
            // 设置随机颜色
            graphic.setColor(getRandomColor());
            // 随机画线
            graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),
                    ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
        }
        // 7.返回验证码和图片
        return new Object[] { sb.toString(), image };
    }
    /**
     * 随机取色
     */
    public static Color getRandomColor() {
        Random ran = new Random();
        Color color = new Color(ran.nextInt(256), ran.nextInt(256), ran.nextInt(256));
        return color;
    }
    public static void main(String[] args) throws IOException {
        Object[] objs = createImage();
        BufferedImage image = (BufferedImage) objs[1];
        OutputStream os = new FileOutputStream("d:/1.png");
        ImageIO.write(image, "jpeg", os);
        os.close();
    }
}