如何通过servletResponse生成验证码图片？

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验证码示例代码：

javapackage com.cmcc.java;

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;

public class VerificationCodeGenerator { public BufferedImage generateVerificationCode(int width, int height) throws ServletException { BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g=image.createGraphics();

// 设置背景颜色 g.setColor(Color.WHITE); g.fillRect(0, 0, width, height);

// 设置字体 g.setFont(new Font(Arial, Font.BOLD, 30));

// 随机生成验证码字符 String code=generateRandomCode(6);

// 绘制验证码字符 g.setColor(Color.BLACK); for (int i=0; i

// 添加干扰线 g.setColor(Color.GRAY); for (int i=0; i <10; i++) { g.drawLine(new Random().nextInt(width), new Random().nextInt(height), new Random().nextInt(width), new Random().nextInt(height)); }

g.dispose(); return image; }

private String generateRandomCode(int length) { String characters=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789; StringBuilder sb=new StringBuilder(); Random random=new Random(); for (int i=0; i 验证码

package com.cmcc.java; 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; /** * @author create by zhousq * @date 2017年9月25日---上午8:39:20 * @problem * @answer * @action */ public class IdentityServlet extends HttpServlet { /** * */ private static final long serialVersionUID = 1L; public static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' }; // 随机数 public static Random random = new Random(); // 获取6位随机数 public static String getRandomString() { StringBuffer buffer = new StringBuffer(); // 字符串缓存 for (int i = 0; i < 6; i++) { buffer.append(CHARS[random.nextInt(CHARS.length)]); } return buffer.toString(); } // 获取随机颜色 public static Color getRandomColor() { return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)); } public static Color getReverseColor(Color c) { return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue()); } @Override public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //设置输出类型 resp.setContentType("image/jpg"); //随机字符串 String randomString = getRandomString(); req.getSession(true).setAttribute("randomString", randomString); int width = 100;//图片宽度 int height = 30;//图片高度 Color color = getRandomColor();//随机颜色 Color reverse = getReverseColor(color);//反色，用于前景色 //创建一份彩色图片 BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g = bi.createGraphics(); //获取绘图对象 g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16)); //设置字体 g.setColor(color); g.fillRect(0, 0, width, height); //绘制背景 g.setColor(reverse); g.drawString(randomString, 18, 20); //绘制随机字符 for (int i=0,n=random.nextInt(100);i