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Java 随机生成验证码，支持大小写字母、数字、随机字体

 
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java随机产生验证码，可以随机生成数字、大写字母、小写字母。还可以随机生成文字字体、及大小。在图片上面可能字体都不不同、大小不等。 
 
package com.hoo.util; 
 

import java.awt.Color; 
 import java.awt.Font; 
 import java.awt.Graphics; 
 import java.awt.image.BufferedImage; 
 import java.util.Random; 
 
import javax.imageio.ImageIO; 
 import javax.servlet.http.HttpServletRequest; 
 import javax.servlet.http.HttpServletResponse; 
 /**
 * <b>function:</b> 验证码生成工具类
 * @project NetWorkService
 * @package com.hoo.util 
 * @fileName ValidCodeUtils.java
 * @createDate 2010-8-3 下午03:05:50
 * @author hoojo
 */ 
 @SuppressWarnings("unused") 
 public class ValidCodeUtils { 
 /*********************************************************************
  * 验证码宽度
  */ 
 public static int WIDTH = 60; 
 /***
  * 验证码高度
  */ 
 public static int HEIGHT = 20; 
  
 /**********************************************************************
  * 验证码背景颜色COLOR_FC_BG 应当小于COLOR_BC_BG
  */ 
 public static int COLOR_FC_BG = 200; 
 /***
  * 验证码背景颜色COLOR_FC_BG 应当小于COLOR_BC_BG
  */ 
 public static int COLOR_BC_BG = 250; 
  
 /**********************************************************************
  * 验证码背景干扰线颜色COLOR_FC_LINE 应当小于COLOR_BC_LINE
  */ 
 public static int COLOR_FC_LINE = 160; 
 /***
  * 验证码背景干扰线颜色COLOR_FC_LINE 应当小于COLOR_BC_LINE
  */ 
 public static int COLOR_BC_LINE = 200; 
  
 /***************************************************************************
  * 验证码颜色COLOR_FC_CODE 应当小于COLOR_BC_CODE
  */ 
 public static int COLOR_FC_CODE = 20; 
 /***
  * 验证码颜色COLOR_FC_CODE 应当小于COLOR_BC_CODE
  */ 
 public static int COLOR_BC_CODE = 170; 
  
 /***************************************************************************
  * 生成在指定范围内的颜色
  * @param fc 范围fc color值 小于255
  * @param bc 范围bc color值 小于255
  * @return Color
  */ 
 private static Color getRandColor(int fc, int bc) { 
     Random random = new Random(); 
     if (fc < 0) 
  fc = 0; 
     if (bc < 0) 
  bc = 1; 
     if (fc > 255) 
  fc = 255; 
     if (bc > 255) 
  bc = 255; 
     if (bc == fc)  
  bc += 10; 
     int temp = 0; 
     if (bc < fc) { 
  temp = bc; 
  bc = fc; 
  fc = temp; 
     } 
     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); 
 } 
 
/**
  * <b>function:</b> 生成图片方法
  * @createDate 2010-8-3 下午03:06:22
  * @author hoojo
  * @param request HttpServletRequest
  * @param response HttpServletResponse
  * @return boolean
  * @throws Exception
  */ 
 public static boolean getImage(HttpServletRequest request, HttpServletResponse response) throws Exception{ 
     response.reset(); 
     response.setContentType("image/jpeg"); 
     // 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      
     BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB); 
 
    // 获取图形上下文 
     Graphics img = image.getGraphics(); 
     // 生成随机类 
     Random random = new Random(); 
 
    // 设定背景色 
     img.setColor(getRandColor(COLOR_FC_BG, COLOR_BC_BG)); 
     img.fillRect(0, 0, WIDTH, HEIGHT); 
 
    // 设定字体 
     img.setFont(new Font("Times New Roman", Font.PLAIN, 18)); 
 
    // 画边框 
     // g.setColor(new Color()); 
     // 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 
     img.setColor(getRandColor(COLOR_FC_LINE, COLOR_BC_LINE)); 
     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); 
  img.drawLine(x, y, x + xl, y + yl); 
     } 
 
    // 取随机产生的认证码(4位数字) 
     String codeValue = ""; 
     for (int i = 0; i < 4; i++) { 
  //String rand = String.valueOf(random.nextInt(10)); 
  String rand = getRandomChar(); 
  codeValue = codeValue.concat(rand); 
  img.setFont(getRandomFont());//随机字体 
  // 将认证码显示到图象中 
  img.setColor(getRandColor(COLOR_FC_CODE, COLOR_BC_CODE)); 
  img.drawString(rand, 13 * i + 6, 16); 
     } 
     request.getSession().setAttribute("codeValue", codeValue); 
     // 图象生效 
     img.dispose(); 
     // 输出图象到页面 
     return ImageIO.write(image, "JPEG", response.getOutputStream()); 
 } 
  
 /**
  * 随机生成字符，含大写、小写、数字
  * <b>function:</b> 功能
  * @createDate 2010-8-23 上午10:33:55
  * @author hoojo
  * @return
  */ 
 public static String getRandomChar() { 
     int index = (int) Math.round(Math.random() * 2); 
     String randChar = ""; 
     switch (index) { 
     case 0://大写字符 
  randChar = String.valueOf((char)Math.round(Math.random() * 25 + 65)); 
  break; 
     case 1://小写字符 
  randChar = String.valueOf((char)Math.round(Math.random() * 25 + 97)); 
  break; 
     default://数字 
  randChar = String.valueOf(Math.round(Math.random() * 9)); 
  break; 
     } 
     return randChar; 
 } 
  
 /**
  * <b>function:</b> 随机生成字体、文字大小
  * @createDate 2010-8-23 上午10:44:22
  * @author hoojo
  * @return
  */ 
 public static Font getRandomFont() { 
     String[] fonts = {"Georgia", "Verdana", "Arial", "Tahoma", "Time News Roman", "Courier New", "Arial Black", "Quantzite"}; 
     int fontIndex = (int)Math.round(Math.random() * (fonts.length - 1)); 
     int fontSize = (int) Math.round(Math.random() * 4 + 16); 
     return new Font(fonts[fontIndex], Font.PLAIN, fontSize); 
 } 
 } 
 
其中验证码的值是保存在session中：request.getSession().setAttribute("codeValue", codeValue);
 比较用户输入的值和session中的codeValue是否相等即可；
 
下面是jsp页面调用servlet：ValidCodeServlet.java
 
ValidCodeServlet中调用了上面的ValidCodeUtils 验证码生成工具类
 
package com.hoo.servlet; 
 
import java.io.IOException; 
 import javax.servlet.ServletException; 
 import javax.servlet.http.HttpServlet; 
 import javax.servlet.http.HttpServletRequest; 
 import javax.servlet.http.HttpServletResponse; 
 
import com.hoo.util.ValidCodeUtils; 
 
@SuppressWarnings("serial") 
 public class ValidCodeServlet extends HttpServlet { 
  
 public void doGet(HttpServletRequest request, HttpServletResponse response) 
  throws ServletException, IOException { 
     try { 
  ValidCodeUtils.getImage(request, response); 
     } catch (Exception e) { 
  e.printStackTrace(); 
     } 
 } 
 
public void doPost(HttpServletRequest request, HttpServletResponse response) 
  throws ServletException, IOException { 
     doGet(request, response); 
 } 
 } 
 
 
 
jsp页面调用servlet方法即可
 
 
 
js：reloadValidCode方法 
 
function reloadValidCode(o) { 
 o.src = "${pageContext.request.contextPath }/validCodeServlet?timed=" + new Date().getMilliseconds(); 
 } 
 这里的"timed=" + new Date().getMilliseconds();是需要防止IE缓存用的 
 
html标签： 
 <img src="${pageContext.request.contextPath }/validCodeServlet" title="看不清，点击刷新" onclick="reloadValidCode(this)"/> 
 直接跟Servlet名称配置的url即可，和web.xml配置对应。主要调用路径${pageContext.request.contextPath }/validCodeServlet这样会带上根目录，比较保险。 
 
web.xml中validCodeServlet配置 
 <servlet> 
 <servlet-name>validCodeServlet</servlet-name> 
 <servlet-class>com.hoo.servlet.ValidCodeServlet</servlet-class> 
 </servlet> 
 
<servlet-mapping> 
 <servlet-name>validCodeServlet</servlet-name> 
 <url-pattern>/validCodeServlet</url-pattern> 
 </servlet-mapping>

 

查看代码 
  1 package cn.edu.bzu;
  2 
  3 import java.awt.Color;
  4 import java.awt.Font;
  5 import java.awt.Graphics2D;
  6 import java.awt.image.BufferedImage;
  7 import java.io.IOException;
  8 import java.util.Random;
  9 
 10 import javax.imageio.ImageIO;
 11 import javax.servlet.ServletException;
 12 import javax.servlet.ServletOutputStream;
 13 import javax.servlet.http.HttpServlet;
 14 import javax.servlet.http.HttpServletRequest;
 15 import javax.servlet.http.HttpServletResponse;
 16 
 17 import com.sun.image.codec.jpeg.JPEGCodec;
 18 import com.sun.image.codec.jpeg.JPEGImageEncoder;
 19 
 20 public class GetKey extends HttpServlet {
 21  //定义可选择的字符
 22  public static final char[] CHARS={'2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z'};
 23  static Random random=new Random();
 24  
 25  public String getRandomString(){
 26 
 27   StringBuffer buffer=new StringBuffer();
 28   for(int i=0;i<6;i++){ //生成六个字符
 29    buffer.append(CHARS[random.nextInt(CHARS.length)]);
 30   }
 31   return buffer.toString();
 32  }
 33  
 34  public static Color getRandomColor(){  //得到随机颜色
 35   return new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255));  
 36  }
 37  
 38  public static Color getReverseColor(Color c){ //得到颜色的反色
 39   return new Color(255-c.getRed(),255-c.getGreen(),255-c.getBlue());
 40  }
 41  
 42  public void doGet (HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
 43   response.setContentType("image/jpeg");  //设置输出类型
 44   String randomString=getRandomString();
 45   //将getSession（）设置为true，当会话不存在是返回null
 46   request.getSession(true).setAttribute("randomString",randomString);
 47   
 48   //设置图片的宽、高
 49   int width=100;
 50   int height=30;
 51   
 52   Color bcolor=getRandomColor(); //前景色
 53   Color fcolor=getReverseColor(getRandomColor()); //设置背景色
 54   
 55   //创建一个彩色图片
 56   BufferedImage bimage=new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
 57   //创建绘图对象
 58   Graphics2D g=bimage.createGraphics();
 59   //字体样式为宋体,加粗，20磅
 60   g.setFont(new Font("宋体",Font.BOLD,20));
 61   //先画出背景色
 62   g.setColor(bcolor);
 63   g.fillRect(0,0,width,height);
 64   //再画出前景色
 65   g.setColor(fcolor);
 66   //绘制随机字符
 67   g.drawString(randomString, 20,22);
 68   //画出干扰点
 69   for(int i=0,n=random.nextInt(100);i<n;i++){
 70    g.drawRect(random.nextInt(width), random.nextInt(height),1, 1);
 71   }
 72   
 73   ServletOutputStream outstream=response.getOutputStream();
 74   JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(outstream);
 75   
 76   encoder.encode(bimage);
 77   outstream.flush();
 78 
 79 
 80  }
 81 }
 82 
 83  ====================================================
 84 前台的JSP文件：
 85 <%@ page language="java" contentType="text/html;charset=utf-8" %>
 86 <%@ page import="cn.edu.bzu.GetKey" %>
 87 <jsp:useBean id="show" scope="page" class="cn.edu.bzu.GetKey"/>
 88 <html>
 89  <head><title>登陆</title>
 90  <script language="javascript" type="text/javascript">
 91   function changeImage(){
 92    document.getElementById("ch").disabled=true;
 93    document.getElementById("imc").src="http://localhost:8080/ExerciseTest/GetKey?ts="+newDate().getTime();
 94   }
 95  </script>
 96  </head>
 97  <body>
 98  <form action="GoTest" method="get">
 99   <table width="400" height="200" border="1" borderColor="blue">
100    <tr>
101      <td colspan="4" align="center">
102     后台登陆
103       </td>
104    </tr>
105    <tr>
106     <td>用户名:</td>
107     <td colspan="3"><input type="text" name="username" class="width:200px;height:30px;font-family:微软雅黑"/></td>
108    </tr>
109    <tr>
110      <td>
111        密&nbsp;&nbsp;码:
112      </td>
113      <td colspan="3">
114      <input type="password" name="pass" class="width:200px;height:30px;"/>
115      </td>
116    </tr>
117     <tr>
118       <td>
119        验证码:
120       </td>
121       <td>
122        <input type="text" name="checkkey" class="width:80px;height:30px;padding-top:4px;"/>
123       </td>
124       <td>
125       <img src="http://localhost:8080/ExerciseTest/GetKey" id="imc" onload="ch.disabled=false;"/>
126       </td>
127       <td>
128      <a href="javascript:onclick=changeImage()" id="ch">看不清,换一张</a>
129       </td>
130     </tr>
131    <tr>
132      <td align="center" >

 

 

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| SUN官方API中文版【JDK1.6】
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