這里寫(xiě)了一個(gè)生成驗(yàn)證碼的demo
前臺(tái)可以訪(fǎng)問(wèn)該servlet頁(yè)面顯示驗(yàn)證碼
驗(yàn)證碼 后臺(tái)存的session名稱(chēng)為vCode 判斷驗(yàn)證碼是否正確時(shí)可以直接調(diào)用
前臺(tái)通過(guò)
這里你就自己引入jq吧

<img src="ValidateCodeServle" id="src"> <a onclick="code()">看不清楚，換一張</a> <script>function code(){$.("#src").attr({src:codeservlet()});}function codeservlet(){$.post("ValidateCodeServle",,function(data){return data;})} </script> package com.jdbc.util;import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random;import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;/*** Servlet implementation class ValidateCodeServle*/ @WebServlet("/ValidateCodeServle") public class ValidateCodeServle extends HttpServlet {private static final long serialVersionUID = 1L;/*** @see HttpServlet#HttpServlet()*/public ValidateCodeServle() {super();// TODO Auto-generated constructor stub}/*** @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}/*** @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubresponse.setHeader("Pragma", "No-Cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expries", 0);// 隨機(jī)數(shù)生成類(lèi)Random random = new Random();// 定義驗(yàn)證碼的位數(shù)int size = 5;// 定義變量保存生成的驗(yàn)證碼String vCode = "";char c;// 產(chǎn)生驗(yàn)證碼for (int i = 0; i < size; i++) {// 產(chǎn)生一個(gè)26以?xún)?nèi)的隨機(jī)整數(shù)int number = random.nextInt(26);// 如果生成的是偶數(shù)，則隨機(jī)生成一個(gè)數(shù)字if (number % 2 == 0) {c = (char) ('0' + (char) ((int) (Math.random() * 10)));// 如果生成的是奇數(shù)，則隨機(jī)生成一個(gè)字母} else {c = (char) ((char) ((int) (Math.random() * 26)) + 'A');}vCode = vCode + c;}// 保存生成的5位驗(yàn)證碼request.getSession().setAttribute("vCode", vCode);// 驗(yàn)證碼圖片的生成// 定義圖片的寬度和高度int width = (int) Math.ceil(size * 20);int height = 30;BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// 獲取圖片的上下文Graphics gr = image.getGraphics();// 設(shè)定圖片背景顏色gr.setColor(Color.WHITE);gr.fillRect(0, 0, width, height);// 設(shè)定圖片邊框gr.setColor(Color.GRAY);gr.drawRect(0, 0, width - 1, height - 1);// 畫(huà)十條干擾線(xiàn)for (int i = 0; i < 5; i++) {int x1 = random.nextInt(width);int y1 = random.nextInt(height);int x2 = random.nextInt(width);int y2 = random.nextInt(height);gr.setColor(randomColor());gr.drawLine(x1, y1, x2, y2);}// 設(shè)置字體，畫(huà)驗(yàn)證碼gr.setColor(randomColor());gr.setFont(randomFont());gr.drawString(vCode, 10, 22);// 圖像生效gr.dispose();// 輸出到頁(yè)面ImageIO.write(image, "JPEG", response.getOutputStream());}// 生成隨機(jī)的顏色private Color randomColor() {int red = r.nextInt(150);int green = r.nextInt(150);int blue = r.nextInt(150);return new Color(red, green, blue);}private String[] fontNames = { "宋體", "華文楷體", "黑體", "微軟雅黑", "楷體_GB2312" };private Random r = new Random();// 生成隨機(jī)的字體private Font randomFont() {int index = r.nextInt(fontNames.length);String fontName = fontNames[index];// 生成隨機(jī)的字體名稱(chēng)int style = r.nextInt(4);int size = r.nextInt(3) + 24; // 生成隨機(jī)字號(hào), 24 ~ 28return new Font(fontName, style, size);}}

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