package com.library.util;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;

/**
 * 生成图片验证码
 * @author cyy
 *
 */
public class PictureCode {
    
    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)); 
    } 
}