JSP驗證碼產生點擊按鈕更新

最後更新：2018-12-03 來源：互聯網

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點擊“看不清換一張”

測試案例：

Index.jsp

<%@ page contentType="text/html; charset=utf-8" language="java"import="java.util.*" errorPage=""%><HTML><head><title>測試</title></head><BODY id="body"><form><img border=0 src="ImageMaskServlet" width="40" height="16" id = "imageMask"><a href = "#" style = "font-size: 13px;margin-left: 5px;" onclick = "myReload()">看不清換一張</a></form>    <script type="text/javascript">    //用於重新整理驗證碼 function myReload(){              document.getElementById("imageMask").src=document.getElementById("imageMask").src+"?nocache="+new Date().getTime();          }  </script></BODY></HTML>

ImageMaskServlet

package javaServlet;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.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ImageMaskServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);int width = 60, height = 20;//建立圖象 BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);//擷取圖形上下文 Graphics graphics = image.getGraphics();//產生隨機類Random random = new Random();//設定背景色 graphics.setColor(getRandColor(200, 250));//驗證碼大小graphics.fillRect(0, 0, width, height);//設定字型graphics.setFont(new Font("Times New Roman", Font.PLAIN, 18));    //graphics.setColor(getRandColor(160, 200));//隨機產生155條幹擾線，使圖象中的認證碼不易被其它程式探測到for (int i = 0; i < 155; i++) {int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(12);int yl = random.nextInt(12);graphics.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++) {//0~9String rand = String.valueOf(random.nextInt(10));sRand += rand;//設定數字顏色graphics.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));//把隨機產生的4位元畫在圖片上graphics.drawString(rand, 13 * i + 6, 16);}//放在session中request.getSession().setAttribute("imageMask", sRand);//圖象生效 graphics.dispose();//輸出圖象到頁面 ImageIO.write(image, "JPEG", response.getOutputStream());}//產生隨機顏色public Color getRandColor(int fc, int bc) {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);}}

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