package util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 验证码生成类
 * <p>
 * @author admin
 *
 */
public class RandomValidateCode {
 
 public static final String RANDOMCODEKEY= "RANDOMVALIDATECODEKEY";//放到session中的key 
 //private String randString = "0123456789";//随机产生只有数字的字符串 private String
 private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生只有字母的字符串
 //private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生数字与字母组合的字符串 
 private int width = 95;// 图片宽 
 private int height = 25;// 图片高 
 private int lineSize = 40;// 干扰线数量 
 private int stringNum = 4;// 随机产生字符数量 
 
 private Random random = new Random(); 
 
 /*
 * 获得字体
 */ 
 private Font getFont() { 
 return new Font("Fixedsys", Font.CENTER_BASELINE, 18); 
 } 
 
 /*
 * 获得颜色
 */ 
 private Color getRandColor(int fc, int bc) { 
 if (fc > 255) 
 fc = 255; 
 if (bc > 255) 
 bc = 255; 
 int r = fc + random.nextInt(bc - fc - 16); 
 int g = fc + random.nextInt(bc - fc - 14); 
 int b = fc + random.nextInt(bc - fc - 18); 
 return new Color(r, g, b); 
 } 
 
 /**
 * 生成随机图片
 */ 
 public void getRandcode(HttpServletRequest request, 
 HttpServletResponse response) { 
 HttpSession session = request.getSession(); 
 // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类 
 BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
 Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作 
 g.fillRect(0, 0, width, height); 
 g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18)); 
 g.setColor(getRandColor(110, 133)); 
 // 绘制干扰线 
 for (int i = 0; i <= lineSize; i++) { 
 drowLine(g); 
 } 
 // 绘制随机字符 
 String randomString = ""; 
 for (int i = 1; i <= stringNum; i++) { 
 randomString = drowString(g, randomString, i); 
 } 
 //将生成的随机字符串保存到session中,而jsp界面通过session.getAttribute("RANDOMCODEKEY"), 
 //获得生成的验证码,然后跟用户输入的进行比较 
 session.removeAttribute(RANDOMCODEKEY);
 session.setAttribute(RANDOMCODEKEY, randomString);
 g.dispose(); 
 try { 
 // 将内存中的图片通过流动形式输出到客户端 
 ImageIO.write(image, "JPEG", response.getOutputStream()); 
 } catch (Exception e) { 
 e.printStackTrace(); 
 } 
 
 } 
 
 /*
 * 绘制字符串
 */ 
 private String drowString(Graphics g, String randomString, int i) { 
 g.setFont(getFont()); 
 g.setColor(new Color(random.nextInt(101), random.nextInt(111), random 
 .nextInt(121))); 
 String rand = String.valueOf(getRandomString(random.nextInt(randString 
 .length()))); 
 randomString += rand; 
 g.translate(random.nextInt(3), random.nextInt(3)); 
 g.drawString(rand, 13 * i, 16); 
 return randomString; 
 } 
 
 /*
 * 绘制干扰线
 */ 
 private void drowLine(Graphics g) { 
 int x = random.nextInt(width); 
 int y = random.nextInt(height); 
 int xl = random.nextInt(13); 
 int yl = random.nextInt(15); 
 g.drawLine(x, y, x + xl, y + yl); 
 } 
 
 /*
 * 获取随机的字符
 */ 
 public String getRandomString(int num) { 
 return String.valueOf(randString.charAt(num)); 
 } 
}