java通過Servlet產生驗證碼__java

實體類具體寫法

package com.han.model;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;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;public class ValidateCodeServlet extends HttpServlet {/** *  */private static final long serialVersionUID = 2376992603034716655L;private final Font mFont = new Font("Arial Black", Font.PLAIN, 15); // 設定字型private final int lineWidth = 2; // 幹擾線的長度=1.414*lineWidthprivate final int width = 88; // 定義圖形大小private final int height = 25; // 定義圖形大小private final int count = 200;/** * 描述： *  * @param fc *            描述： * @param bc *            描述： *  * @return 描述： */private Color getRandColor(int fc, int bc) { // 取得給定範圍隨機顏色final Random random = new Random();if (fc > 255) {fc = 255;}if (bc > 255) {bc = 255;}final int r = fc + random.nextInt(bc - fc);final int g = fc + random.nextInt(bc - fc);final int b = fc + random.nextInt(bc - fc);return new Color(r, g, b);}// 處理post@Overridepublic void doPost(final HttpServletRequest request,final HttpServletResponse response) throws ServletException,IOException {doGet(request, response);}/** * 描述： *  * @param request *            描述： * @param response *            描述： *  * @throws ServletException *             描述： * @throws IOException *             描述： */@Overridepublic void doGet(final HttpServletRequest request,final HttpServletResponse response) throws ServletException,IOException { response.reset();// 設定頁面不緩衝response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);response.setContentType("image/gif");// 在記憶體中建立圖象final BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);// 擷取圖形上下文final Graphics2D g = (Graphics2D) image.getGraphics();// 產生隨機類final Random random = new Random();// 設定背景色g.setColor(getRandColor(200, 250)); // ---1g.fillRect(0, 0, width, height);// 設定字型g.setFont(mFont);// 畫邊框g.setColor(getRandColor(0, 20)); // ---2//距離g.drawRect(0, 0, width -1, height - 1);// 隨機產生幹擾線，使圖象中的認證碼不易被其它程式探測到for (int i = 0; i < count; i++) {g.setColor(getRandColor(150, 200)); // ---3final int x = random.nextInt(width - lineWidth - 1) + 1; // 保證畫在邊框之內final int y = random.nextInt(height - lineWidth - 1) + 1;final int xl = random.nextInt(lineWidth);final int yl = random.nextInt(lineWidth);g.drawLine(x, y, x + xl, y + yl);}// 取隨機產生的認證碼(4位元字)String sRand = "";for (int i = 0; i < 4; i++) {final String rand = String.valueOf(random.nextInt(10));sRand += rand;// 將認證碼顯示到圖象中,調用函數出來的顏色相同，可能是因為種子太接近，所以只能直接產生g.setColor(new Color(20 + random.nextInt(130), 20 + random.nextInt(130), 20 + random.nextInt(130))); // --4--50-100            //第一個參數是要畫上去的字串    後面兩個參數是針對 (0,0) x軸和y軸g.drawString(rand, (13 * i) + 10, 20);}// 將認證碼存入SESSIONrequest.getSession().setAttribute("validateCode", sRand);// 圖象生效         //它的作用是銷毀程式中指定的圖形介面資源，如果在使用了graphics獲得windows一些圖形資源，而不進行關閉的話，由於後期多人使用就會造成記憶體溢出的情況的，導致程式卡死。g.dispose();final java.io.OutputStream os = response.getOutputStream();// 輸出圖象到頁面ImageIO.write(image, "PNG", os);os.flush();os.close();}}

web.xml檔案的配置

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list>  <servlet>    <servlet-name>ValidateCodeServlet</servlet-name>    <servlet-class>com.han.model.ValidateCodeServlet</servlet-class>     <init-param> <param-name>width</param-name> <param-value>200</param-value> </init-param> <init-param> <param-name>height</param-name> <param-value>80</param-value> </init-param> <init-param> <param-name>codeCount</param-name> <param-value>5</param-value> </init-param>   </servlet>  <servlet-mapping>    <servlet-name>ValidateCodeServlet</servlet-name>    <url-pattern>/ValidateCodeServlet</url-pattern>  </servlet-mapping></web-app>

jsp頁面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'index.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>    驗證碼：<img src="ValidateCodeServlet"  class="img-rounded" onclick="this.src='ValidateCodeServlet?'+Math.random();" />  </body></html>