如何用Java代碼段生成四位數(shù)字加字母的驗證碼？

不知道你問的是不是生成這種圖片驗證碼？如果只要一個隨機四位數(shù) 那這行代碼就夠了(new Random().nextInt(9000) + 1000;),如果是生成頁面圖片驗證碼就是下面的了: //設(shè)定 響應模式 resp.setContentType("image/jpeg"); // 生成令牌環(huán)數(shù)據(jù); Integer token = new Random().nextInt(9000) + 1000; // 保存令牌環(huán)數(shù)據(jù)到session中 req.getSession().setAttribute(IMAGE_TOKEN_NAME, token); // 生成令牌環(huán)圖片 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();

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我自己做的系統(tǒng)里面用作驗證碼的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("當前驗證碼為:"+session.getAttribute("randNum")); os.flush(); os.close(); os=null; response.flushBuffer(); out.clear(); out = pageContext.pushBody(); % /body/html

用java怎么制作驗證碼

原理:

1.隨機生成4個數(shù)字 用到了Random類

2.對這4個數(shù)字設(shè)置字體格式 用 setFont方法

3.改變字體顏色用setColor 然后隨機生成顏色

代碼如下

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 {

// 發(fā)送圖片不能夠添加這2行代碼

// response.setContentType("text/html;charset=UTF-8");

// request.setCharacterEncoding("UTF-8");

int width=100;

int height=50;

//獲得一張圖片

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("宋體",Font.BOLD,30));

Random random=new Random();

// 填充的字符串

String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

//緩存生成的驗證碼

StringBuffer stringbuffer=new StringBuffer();

//隨機生成驗證碼的顏色和字符

for(int i=0;i4;i++)

{ //設(shè)置隨機顏色

g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));

int index=random.nextInt(62);//這里的62就是從填充字符段中隨意選取一個位置

String str1=str.substring(index,index+1);

g.drawString(str1, 20*i, 30);//x,y數(shù)值設(shè)置太小會顯示不出來

stringbuffer.append(str1);

}

//將生成的驗證碼存到服務器

request.getSession().setAttribute("checkcode", stringbuffer.toString());//key和value

//將圖片發(fā)送給瀏覽器

ImageIO.write(image, "jpg", response.getOutputStream());

}

}

用戶登錄界面代碼

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");// 設(shè)置服務器發(fā)送給瀏覽器的編碼方式

request.setCharacterEncoding("UTF-8"); // 客戶端向服務器提交的數(shù)據(jù)的解碼方式

// 獲得用戶提交的數(shù)據(jù)

String checkcode = request.getParameter("checkcode");

System.out.println(checkcode);

// 判斷輸入的驗證碼是不是符合

HttpSession session = request.getSession();// session是存放數(shù)據(jù)的地方

String str = (String) session.getAttribute("checkcode");

if (str != null) {

if (checkcode點抗 pareToIgnoreCase(str) == 0) // 驗證碼忽略大小寫

response.getWriter().println("驗證碼輸入正確");

else

response.getWriter().println("驗證碼輸入錯誤");

}

else response.getWriter().println("驗證碼失效");

// 使用完的驗證碼信息要刪除,返回原頁面再輸一次,驗證碼就失效了

session.removeAttribute("checkcode");

}

}

本人初學Java，有什么好的圖形驗證碼推薦嗎？

Java是一種流行的編程語言，驗證碼是一種常用的網(wǎng)絡安全技術(shù)。目前，市面上有多種免費的PHP驗證碼可供選擇，例如KgCaptcha等。

怎么用Java代碼實現(xiàn)一個驗證碼，求具體實現(xiàn)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?{

//?驗證碼字符集

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'};

//?字符數(shù)量

private?static?final?int?SIZE?=?4;

//?干擾線數(shù)量

private?static?final?int?LINES?=?5;

//?寬度

private?static?final?int?WIDTH?=?80;

//?高度

private?static?final?int?HEIGHT?=?40;

//?字體大小

private?static?final?int?FONT_SIZE?=?30;

/**

*?生成隨機驗證碼及圖片

*?返回的數(shù)組中，第1個值是驗證碼，第2個值是圖片

*/

public?static?Object[]?createImage()?{

StringBuffer?sb?=?new?StringBuffer();

//?1.創(chuàng)建空白圖片

BufferedImage?image?=?new?BufferedImage(

WIDTH,?HEIGHT,?BufferedImage.TYPE_INT_RGB);

//?2.獲取圖片畫筆

Graphics?graphic?=?image.getGraphics();

//?3.設(shè)置畫筆顏色

graphic.setColor(Color.LIGHT_GRAY);

//?4.繪制矩形背景

graphic.fillRect(0,?0,?WIDTH,?HEIGHT);

//?5.畫隨機字符

Random?ran?=?new?Random();

for?(int?i?=?0;?i?SIZE;?i++)?{

//?取隨機字符索引

int?n?=?ran.nextInt(chars.length);

//?設(shè)置隨機顏色

graphic.setColor(getRandomColor());

//?設(shè)置字體大小

graphic.setFont(new?Font(

null,?Font.BOLD?+?Font.ITALIC,?FONT_SIZE));

//?畫字符

graphic.drawString(

chars[n]?+?"",?i?*?WIDTH?/?SIZE,?HEIGHT?/?2);

//?記錄字符

sb.append(chars[n]);

}

//?6.畫干擾線

for?(int?i?=?0;?i??LINES;?i++)?{

//?設(shè)置隨機顏色

graphic.setColor(getRandomColor());

//?隨機畫線

graphic.drawLine(ran.nextInt(WIDTH),?ran.nextInt(HEIGHT),

ran.nextInt(WIDTH),?ran.nextInt(HEIGHT));

}

//?7.返回驗證碼和圖片

return?new?Object[]{sb.toString(),?image};

}

/**

*?隨機取色

*/

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();

}

}

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