验证码部分的java代码怎么写

package com.bbs.servlet;

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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.io.PrintWriter;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.servlet.ServletException;

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 Image extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("image/jpeg");

OutputStream out = response.getOutputStream();

response.setHeader("Pragma","No-cache");

response.setHeader("Cache-Control","no-cache");

response.setDateHeader("Expires", 0);

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));

// 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(180, 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 =setRandValue(request);

if(sRand!=null)

for (int i = 0; i sRand.length(); i++) {

g.setColor(new Color(20 + random.nextInt(200), 20 + random

.nextInt(200), 20 + random.nextInt(200)));

// 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(sRand.charAt(i) + "", 13 * i + 6, 16);

}

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

encoder.encode(image);

// 图象生效

g.dispose();

// 输出图象到页面

// ImageIO.write(image, "JPG", response.getOutputStream());

out.flush();

out.close();

}

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);

}

//48-57对应0-9;65-90对应A-Z;97-122对应a-z;

String setRandValue(HttpServletRequest request) {

Random random = new Random();

String sRand = "";

//这里是生成验证码的位数

for (int i = 0; i 4; i++) {

char c = 0;

int k = random.nextInt(3);

switch (k) {

case 0:

c = (char) (random.nextInt(10) + 48);

break;

case 1:

c = (char) (random.nextInt(26) + 65);

break;

case 2:

c = (char) (random.nextInt(26) + 97);

}

sRand += c;

}

request.getSession().setAttribute("rands", sRand);

return sRand;

}

}

用java怎么制作验证码

原理:

1.随机生成4个数字 用到了Random类

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;i4;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");

}

}

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(fc255) fc=255; if(bc255) 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;i50;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;i4;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

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