根据responseServlet生成图片验证码
代码：
package com.babyDuncan.response;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.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;public class indentity extends HttpServlet {public static final char[] CHARS = { '1', '2', '3', '4', '5', '6', '7','8', '9', 'a', 'f', 'k', 'r', 'y' };public static Random random = new Random();public static String getRandomStriong() {StringBuffer sb = new StringBuffer();for (int i = 0; i < 6; i++) {sb.append(CHARS[random.nextInt(CHARS.length)]);}return sb.toString();}public static Color getRandomColor(){return new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255));}public static Color getOtherColor(Color c){return new Color(255-c.getRed(),255-c.getGreen(),255-c.getBlue());}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("image/jpeg");String randomString = getRandomStriong();this.log(randomString);request.getSession(true).setAttribute("randomString", randomString);int width = 100;int heigth = 30;Color color = getRandomColor();Color otherColor = getOtherColor(color);BufferedImage bi = new BufferedImage(width,heigth,BufferedImage.TYPE_INT_RGB);Graphics2D g = bi.createGraphics();g.setFont(new Font(Font.SANS_SERIF,Font.BOLD,16));g.setColor(color);g.fillRect(0,0,width,heigth);g.setColor(otherColor);g.drawString(randomString, 18, 20);for(int i=0;i<random.nextInt(100);i++){g.drawRect(random.nextInt(width), random.nextInt(heigth), 1, 1);}ServletOutputStream out = response.getOutputStream();JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);encoder.encode(bi);out.flush();}}前端代码为：
<body> <script type="text/javascript"> function reloadImage(){ document.getElementById("btn").disabled = true; document.getElementById("inditity").src = "servlet/indentity?ts="+ new Date().getTime(); } </script> <image src="servlet/indentity" id="inditity" onload="btn.disabled=false;"> </image> <input type="button" value="换张图片" id="btn" onclick="reloadImage()"/> </body>运行结果还行：