不知道你問的是不是生成這種圖片驗(yàn)證碼？如果只要一個(gè)隨機(jī)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(yàn)證碼就是下面的了: //設(shè)定 響應(yīng)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();
10年積累的成都網(wǎng)站制作、成都網(wǎng)站建設(shè)經(jīng)驗(yàn)，可以快速應(yīng)對(duì)客戶對(duì)網(wǎng)站的新想法和需求。提供各種問題對(duì)應(yīng)的解決方案。讓選擇我們的客戶得到更好、更有力的網(wǎng)絡(luò)服務(wù)。我雖然不認(rèn)識(shí)你，你也不認(rèn)識(shí)我。但先網(wǎng)站制作后付款的網(wǎng)站建設(shè)流程，更有麻陽免費(fèi)網(wǎng)站建設(shè)讓你可以放心的選擇與我們合作。
下面簡(jiǎn)單的介紹他們的功能和用途，執(zhí)行效率等。每個(gè)都有各自的優(yōu)缺點(diǎn)看你是做甚什么方面的研究開發(fā)用。.net，是網(wǎng)站編程，現(xiàn)在很多都用這個(gè)，但是這個(gè)語言編程都有統(tǒng)一思路，很好掌握。窒息那個(gè)效率不是很高；php 支持跨平臺(tái)，很容易學(xué)會(huì)，執(zhí)行的效率很高；asp是ASP.net的前身，它比較穩(wěn)定，比.net要弱一點(diǎn)。但是比.net好學(xué)。jsp 是網(wǎng)頁編程，這個(gè)學(xué)習(xí)大約一周就能搞定，不過這個(gè)得多實(shí)踐，不然的話，時(shí)間長(zhǎng)了，就容易忘記。
我自己做的系統(tǒng)里面用作驗(yàn)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(dāng)前驗(yàn)證碼為:"+session.getAttribute("randNum")); os.flush(); os.close(); os=null; response.flushBuffer(); out.clear(); out = pageContext.pushBody(); % /body/html
Java如何實(shí)現(xiàn)驗(yàn)證碼驗(yàn)證功能呢？日常生活中，驗(yàn)證碼隨處可見，他可以在一定程度上保護(hù)賬號(hào)安全，那么他是怎么實(shí)現(xiàn)的呢？
Java實(shí)現(xiàn)驗(yàn)證碼驗(yàn)證功能其實(shí)非常簡(jiǎn)單：用到了一個(gè)Graphics類在畫板上繪制字母，隨機(jī)選取一定數(shù)量的字母隨機(jī)生成，然后在畫板上隨機(jī)生成幾條干擾線。
首先，寫一個(gè)驗(yàn)證碼生成幫助類，用來繪制隨機(jī)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驗(yàn)證碼，同時(shí)輸出一個(gè)圖片
*
*?@param?width
*????????????圖片的寬度
*?@param?height
*????????????圖片的高度
*?@param?imgType
*????????????圖片的類型
*?@param?output
*????????????圖片的輸出流(圖片將輸出到這個(gè)流中)
*?@return?返回所生成的驗(yàn)證碼(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?"畫板"上生成干擾線條?(?50?是線條個(gè)數(shù))
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?"畫板"上繪制字母
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();
}
}?
接著，創(chuàng)建一個(gè)servlet，用來固定圖片大小，以及處理驗(yàn)證碼的使用場(chǎng)景，以及捕獲頁面生成的驗(yàn)證碼（捕獲到的二維碼與用戶輸入的驗(yàn)證碼一致才能通過）。
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?{
//?獲得?當(dāng)前請(qǐng)求?對(duì)應(yīng)的?會(huì)話對(duì)象
HttpSession?session?=?request.getSession();
//?從請(qǐng)求中獲得?URI?(?統(tǒng)一資源標(biāo)識(shí)符?)
String?uri?=?request.getRequestURI();
System.out.println("hello?:?"?+?uri);
final?int?width?=?180;?//?圖片寬度
final?int?height?=?40;?//?圖片高度
final?String?imgType?=?"jpeg";?//?指定圖片格式?(不是指MIME類型)
final?OutputStream?output?=?response.getOutputStream();?//?獲得可以向客戶端返回圖片的輸出流
//?(字節(jié)流)
//?創(chuàng)建驗(yàn)證碼圖片并返回圖片上的字符串
String?code?=?GraphicHelper.create(width,?height,?imgType,?output);
System.out.println("驗(yàn)證碼內(nèi)容:?"?+?code);
//?建立?uri?和?相應(yīng)的?驗(yàn)證碼?的關(guān)聯(lián)?(?存儲(chǔ)到當(dāng)前會(huì)話對(duì)象的屬性中?)
session.setAttribute(uri,?code);
System.out.println(session.getAttribute(uri));
}
}?
接著寫一個(gè)HTML注冊(cè)頁面用來檢驗(yàn)一下：
html
head
meta?charset="UTF-8"
title注冊(cè)/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"?!--?注冊(cè)表單開始?--
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="請(qǐng)輸入用戶名"
/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="請(qǐng)輸入密碼"
/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="請(qǐng)確認(rèn)密碼"
/span
/div
div?class="form-row"
span?class="cell-7"
input?type="text"?name="verifyCode"?placeholder="請(qǐng)輸入驗(yàn)證碼"
/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="注冊(cè)"
/span
/div
/div?!--?注冊(cè)表單結(jié)束?--
/form
/div
/body
/html
效果如下圖：
在控制臺(tái)接收到的圖片中驗(yàn)證碼的變化如下：
當(dāng)點(diǎn)擊刷新頁面的時(shí)候，驗(yàn)證碼也會(huì)隨著變化，但我們看不清驗(yàn)證碼時(shí)，只要點(diǎn)擊驗(yàn)證碼就會(huì)刷新，這樣局部的刷新可以用JavaScript來實(shí)現(xiàn)。
在img
src="/demo/verify/regist.do"中，添加一個(gè)問號(hào)和一串后綴數(shù)字，當(dāng)刷新時(shí)讓后綴數(shù)字不斷改變，那么形成的驗(yàn)證碼也會(huì)不斷變化，我們可以采用的一種辦法是后綴數(shù)字用date代替，date獲取本機(jī)時(shí)間，時(shí)間是隨時(shí)變的，這樣就保證了刷新驗(yàn)證碼可以隨時(shí)變化。
代碼如下：
function?myRefersh(?e?)?{
const?source?=?e.src?;?//?獲得原來的?src?中的內(nèi)容
//console.log(?"source?:?"?+?source??)?;
var?index?=?source.indexOf(?"?"?)?;??//?從?source?中尋找???第一次出現(xiàn)的位置?(如果不存在則返回?-1?)
//console.log(?"index?:?"?+?index??)?;
if(?index??-1?)?{?//?如果找到了????就進(jìn)入內(nèi)部
var?s?=?source.substring(?0?,?index?)?;?//?從?source?中截取?index?之前的內(nèi)容?(?index?以及?index?之后的內(nèi)容都被舍棄?)
//console.log(?"s?:?"?+?s??)?;
var?date?=?new?Date();?//?創(chuàng)建一個(gè)?Date?對(duì)象的?一個(gè)?實(shí)例
var?time?=?date.getTime()?;?//?從?新創(chuàng)建的?Date?對(duì)象的實(shí)例中獲得該時(shí)間對(duì)應(yīng)毫秒值
e.src?=?s?+?"?time="?+?time?;?//?將?加了?尾巴?的?地址?重新放入到?src?上
//console.log(?e.src?)?;
}?else?{
var?date?=?new?Date();
e.src?=?source?+?"?time="?+?date.getTime();
}
}
如回答不詳細(xì)可追問
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(yàn)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(jī)驗(yàn)證碼及圖片
*?返回的數(shù)組中，第1個(gè)值是驗(yàn)證碼，第2個(gè)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(jī)字符
Random?ran?=?new?Random();
for?(int?i?=?0;?i?SIZE;?i++)?{
//?取隨機(jī)字符索引
int?n?=?ran.nextInt(chars.length);
//?設(shè)置隨機(jī)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(jī)顏色
graphic.setColor(getRandomColor());
//?隨機(jī)畫線
graphic.drawLine(ran.nextInt(WIDTH),?ran.nextInt(HEIGHT),
ran.nextInt(WIDTH),?ran.nextInt(HEIGHT));
}
//?7.返回驗(yàn)證碼和圖片
return?new?Object[]{sb.toString(),?image};
}
/**
*?隨機(jī)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();
}
}
現(xiàn)在許多系統(tǒng)的注冊(cè) 登錄或者發(fā)布信息模塊都添加的隨機(jī)碼功能 就是為了避免自動(dòng)注冊(cè)程序或者自動(dòng)發(fā)布程序的使用
驗(yàn)證碼實(shí)際上就是隨機(jī)選擇一些字符以圖片的形式展現(xiàn)在頁面上 如果進(jìn)行提交操作的同時(shí)需要將圖片上的字符同時(shí)提交 如果提交的字符與服務(wù)器session保存的不同 則認(rèn)為提交信息無效 為了避免自動(dòng)程序分析解析圖片 通常會(huì)在圖片上隨機(jī)生成一些干擾線或者將字符進(jìn)行扭曲 增加自動(dòng)識(shí)別的難度
在這里 我們使用servlet來實(shí)現(xiàn)隨機(jī)驗(yàn)證碼的實(shí)現(xiàn)
package servlet; import java awt Color; import java awt Font; import java awt Graphics D; import java awt image BufferedImage; import java util Random; import javax imageio ImageIO; import javax servlet ServletException; import javax servlet ServletOutputStream; import javax servlet import javax servlet import javax servlet import javax servlet /** * 生成隨機(jī)驗(yàn)證碼 * @author bitiliu * */ public class ValidateCodeServlet extends HttpServlet { private static final long serialVersionUID = L; //驗(yàn)證碼圖片的寬度 private int width= ; //驗(yàn)證碼圖片的高度 private int height= ; //驗(yàn)證碼字符個(gè)數(shù) private int codeCount= ; private int x= ; //字體高度 private int fontHeight; private int codeY; char[] codeSequence = { 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 }; /** * 初始化驗(yàn)證圖片屬性 */ public void init() throws ServletException { //從web xml中獲取初始信息 //寬度 String strWidth=this getInitParameter("width"); //高度 String strHeight=this getInitParameter("height"); //字符個(gè)數(shù) String strCodeCount=this getInitParameter("codeCount"); //將配置的信息轉(zhuǎn)換成數(shù)值 try { if(strWidth!=null strWidth length()!= ) { width=Integer parseInt(strWidth); } if(strHeight!=null strHeight length()!= ) { height=Integer parseInt(strHeight); } if(strCodeCount!=null strCodeCount length()!= ) { codeCount=Integer parseInt(strCodeCount); } } catch(NumberFormatException e) {} x=width/(codeCount+ ); fontHeight=height ; codeY=height ; } protected void service(HttpServletRequest req HttpServletResponse resp) throws ServletException java io IOException { //定義圖像buffer BufferedImage buffImg = new BufferedImage( width height BufferedImage TYPE_INT_RGB); Graphics D g = buffImg createGraphics(); //創(chuàng)建一個(gè)隨機(jī)數(shù)生成器類 Random random = new Random(); //將圖像填充為白色 g setColor(Color WHITE); g fillRect( width height); //創(chuàng)建字體 字體的大小應(yīng)該根據(jù)圖片的高度來定 Font font = new Font("Fixedsys" Font PLAIN fontHeight); //設(shè)置字體 g setFont(font); //畫邊框 g setColor(Color BLACK); g drawRect( width height ); //隨機(jī)產(chǎn)生 條干擾線 使圖象中的認(rèn)證碼不易被其它程序探測(cè)到 g setColor(Color BLACK); for(int i = ; i ; i++) { int x = random nextInt(width); int y = random nextInt(height); int xl = random nextInt( ); int yl = random nextInt( ); g drawLine(x y x + xl y + yl); } //randomCode用于保存隨機(jī)產(chǎn)生的驗(yàn)證碼 以便用戶登錄后進(jìn)行驗(yàn)證 StringBuffer randomCode = new StringBuffer(); int red = green = blue = ; //隨機(jī)產(chǎn)生codeCount數(shù)字的驗(yàn)證碼 for (int i = ; i codeCount; i++) { //得到隨機(jī)產(chǎn)生的驗(yàn)證碼數(shù)字 String strRand = String valueOf(codeSequence[random nextInt( )]); //產(chǎn)生隨機(jī)的顏色分量來構(gòu)造顏色值 這樣輸出的每位數(shù)字的顏色值都將不同 red = random nextInt( ); green = random nextInt( ); blue = random nextInt( ); //用隨機(jī)產(chǎn)生的顏色將驗(yàn)證碼繪制到圖像中 g setColor(new Color(red green blue)); g drawString(strRand (i + ) * x codeY); //將產(chǎn)生的四個(gè)隨機(jī)數(shù)組合在一起 randomCode append(strRand); } // 將四位數(shù)字的驗(yàn)證碼保存到Session中 HttpSession session = req getSession(); session setAttribute("validateCode" randomCode toString()); // 禁止圖像緩存 resp setHeader("Pragma" "no cache"); resp setHeader("Cache Control" "no cache"); resp setDateHeader("Expires" ); resp setContentType("image/jpeg"); //將圖像輸出到Servlet輸出流中 ServletOutputStream sos = resp getOutputStream(); ImageIO write(buffImg "jpeg" sos); sos close(); } }
需要在web xml中聲明servlet
servlet servlet nameValidateCodeServlet/servlet name servlet class servlet ValidateCodeServlet/servlet class init param param namewidth/param name param value /param value /init param init param param nameheight/param name param value /param value /init param init param param namecodeCount/param name param value /param value /init param /servlet servlet mapping servlet nameValidateCodeServlet/servlet name url pattern/validateCodeServlet/url pattern /servlet mapping
需要引用的頁面可以這樣來寫
ccid_file values="validateCodeServlet" width= / /
lishixinzhi/Article/program/Java/JSP/201311/19913
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);
// 獲取圖形上下文
Graphics g = image.getGraphics();
// 生成隨機(jī)類
Random random = new Random();
// 設(shè)定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
// 設(shè)定字體
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
// 隨機(jī)產(chǎn)生155條干擾線，使圖象中的認(rèn)證碼不易被其它程序探測(cè)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);
}
// 取隨機(jī)產(chǎn)生的認(rèn)證碼(4位數(shù)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)));
// 調(diào)用函數(shù)出來的顏色相同，可能是因?yàn)榉N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);
// 圖象生效
g.dispose();
// 輸出圖象到頁面
// ImageIO.write(image, "JPG", response.getOutputStream());
out.flush();
out.close();
}
Color getRandColor(int fc, int bc) {// 給定范圍獲得隨機(jī)顏色
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對(duì)應(yīng)0-9;65-90對(duì)應(yīng)A-Z;97-122對(duì)應(yīng)a-z;
String setRandValue(HttpServletRequest request) {
Random random = new Random();
String sRand = "";
//這里是生成驗(yàn)證碼的位數(shù)
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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