Web 开发实现验证码输入功能
首先建一个类生成一个验证码的图片代码如下import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random; import javax.imageio.ImageIO; public class MakeSecurityPic { /** * 生成验证码的字符数字组合 */ private char[] mapTable = { '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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; /** * 获取验证码图片 * * @param width * 图片的宽 * @param height * 图片的高 * @param os * 输出流 * @return */ public String getSecurityPic(Integer width, Integer height, OutputStream os) { if (width == 0) width = 60; if (height == 0) height = 20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // Graphics2D g = image.createGraphics(); // 填充背景色 g.setColor(Color.white); g.fillRect(0, 0, width, height); // 绘制边框 g.setColor(Color.BLACK); g.drawRect(0, 0, width - 1, height - 1); // 验证码 String security = ""; // 随机生成验证码 Random random = new Random(); for (int i = 0; i < 4; i++) { security += mapTable; } // 绘制验证码 g.setColor(Color.BLACK); g.setFont(new Font("MS Sans Serif", Font.PLAIN, 18)); String temp = security.substring(0, 1); g.drawString(temp, 7, 15); temp = security.substring(1, 2); g.drawString(temp, 18, 17); temp = security.substring(2, 3); g.drawString(temp, 28, 18); temp = security.substring(3, 4); g.drawString(temp, 40, 17); // 绘制干扰点 g.setColor(Color.BLACK); for (int i = 0; i < 20; i++) { g.drawOval(random.nextInt(width), random.nextInt(height), 0, 0); } // 释放资源 g.dispose(); try { // 输出图片到缓冲区 ImageIO.write(image, "JPG", os); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return security; }}
再建一个servlet 类型为
response.setContentType("image/jpg");是一个图片类型的。代码如下：package com.security; import java.io.IOException;import java.io.PrintWriter; import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse; public class MakeSecurityServlet 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.setContentType("image/jpg"); MakeSecurityPic msp = new MakeSecurityPic(); String security = msp.getSecurityPic(0, 0, response.getOutputStream()); request.getSession().setAttribute("security", security); } }
显示到jsp页面上如下：
security:<input type="text" name="security"/><img id="securityPic" src="servlet/MakeSecurityServlet"><a href="#" >看不清楚，换一个</a><br>
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