java生成验证码的代码 java验证码实现
用java怎么制作验证码
原理:
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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");
}
}
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();
}
}
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
用java实现：随机获取4位的验证码
验证码是指网页的验证码还是手机的验证码
下面是随机生成四位数的相关代码
import java.util.Random;
public class RandomTest {
public static void main(String[] args) {
System.out.println("Math.random得到小数");
System.out.println(Math.round(Math.random() * 10000));
System.out.println("Random");
System.out.println(new Random().nextInt(9999));
System.out.println("字符串前面补0的话就这样String.format");
System.out.println(String.format("%04d",new Random().nextInt(9999)));
}
}
用java生成6位验证码，由大小写数字组成，不能重复字符
生成随机可以用Random类，不能重复可以考虑放在HashSet中，因为HashSet的值是不能重复的，看代码如下：
public class GenerateRandomLetterAndNum {
public static void main(String[] args) {
SetString store = getletterandnum(6);
printSet(store);
}
public static SetString getletterandnum(int length) {
SetString set =new HashSetString();
for (int i = 0; i length; i++) {
String value = getrandom();
set.add(value);
}
if (set.size()length) { //如果没有生成6位
String value = getrandom();//继续调用生成随机数的方法
set.add(value);
}
return set;
}
private static String getrandom() { //生成随机字母和数字方法
String value = "";
Random random = new Random();
int gen = random.nextInt(2);//0、1、2
String charornum = gen % 2 == 0 ? "char" : "num";
if ("char".equals(charornum)) {
int temp = random.nextInt(2) % 2 == 0 ? 65 : 97;
int ascii = random.nextInt(26);
value += (char) (ascii + temp);
} else if ("num".equalsIgnoreCase(charornum)) {
value += String.valueOf(random.nextInt(10));
}
return value;
}
public static void printSet(Set set){ //打印set的方法
Iterator iterator = set.iterator();
while (iterator.hasNext()) {
String ele = (String) iterator.next();
System.out.print(ele+" ");
}
}
验证码部分的java代码怎么写
package com.bbs.servlet;
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;
}
}
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