verifycode.java

jsp + servlete + jdbc开的管理系统

package hbu.david.cmc;

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

import javax.servlet.ServletOutputStream;
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 zxub 2006-5-25 下午02:50:29
 */
public class VerifyCode
{
	//随机数对象
    static Random r = new Random();
    //预定义的字符串
    //static String ssource = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "0123456789";
    static String ssource = "abcdefghijklmnopqrstuvwxyz" + "0123456789";
    ///把字符串转换成为字节数组
    static char[] src = ssource.toCharArray();
    //预定义的验证码长度
    private int codeLength = 4;

    private HttpServletRequest request = null;
    private HttpServletResponse response = null;
    
    /***********************
     * 构造函数	
     * 默认的验证码长度为codeLength		
     * @param request		
     * @param response		
     * **********************
     */
    public VerifyCode(HttpServletRequest request, HttpServletResponse response)
    {
        this.request = request;
        this.response = response;
        String code = getCode(this.codeLength);
        this.createImage(code);
    }
    /*****************************
     * 构造函数
     * 验证码长度自己设置,codeLength 
     * @param request
     * @param response
     * @param codeLength
     */
    public VerifyCode(HttpServletRequest request, HttpServletResponse response,
            Integer codeLength)
    {
        this.codeLength = codeLength.intValue();
        this.request = request;
        this.response = response;
        String code = getCode(this.codeLength);
        this.createImage(code);
    }

    /**
     * 产生随机字符串
     * 长度为length
     * @param length
     * @return
     */
    private String getCode(int length)
    {
        char[] buf = new char[length];
        int rnd;
        for (int i = 0; i < length; i++)
        {	
            rnd = Math.abs(r.nextInt()) % src.length;

            buf[i] = src[rnd];
        }
        return new String(buf);
    }

    /**
     * 给定范围获得随机颜色
     * 
     * @param fc
     * @param bc
     * @return
     */
    private Color getRandColor(int fc, int bc)
    {
        Random random = new Random();
        if (fc > 255) 
        	fc = 255;
        if (bc > 255) 
        	bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

    /**
     * 调用该方法将得到的验证码生成图象
     * 
     * @param sCode 验证码
     * @return
     */
    private void createImage(String sCode)
    {
    	//设置ContentType类型为 image/jpeg
        this.response.setContentType("image/jpeg");
        // 设置页面不缓存
        this.response.setHeader("Pragma", "No-cache");
        this.response.setHeader("Cache-Control", "no-cache");
        this.response.setDateHeader("Expires", 0);
        // 图象宽度与高度
        int width = 15 * this.codeLength;
        int height = 20;
        BufferedImage image = new BufferedImage(width, height,
            BufferedImage.TYPE_INT_RGB);

        // 获取图形上下文
        Graphics g = image.getGraphics();

        // 生成随机类
        Random random = new Random();

        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);

        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

        // 画边框
        // g.setColor(new Color());
        // g.drawRect(0,0,width-1,height-1)

        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 155; i++)
        {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }

        for (int i = 0; i < this.codeLength; i++)
        {
            String rand = sCode.substring(i, i + 1);
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(60), 20 + random
                .nextInt(120), 20 + random.nextInt(180)));
            g.drawString(rand, 13 * i + 6, 16);
        }
        // 图象生效
        g.dispose();

        this.request.getSession().setAttribute("rand", sCode);
        
        ServletOutputStream outStream;
        try
        {
            outStream = response.getOutputStream();
            
            JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(outStream);

            encoder.encode(image);

            outStream.close();
        }
        catch (IOException e)
        {            
            e.printStackTrace();
        }
    }
    /**
     * 核对验证码是否正确
     * @param request
     * @param response
     * @return
     */
    public static String checkCode(HttpServletRequest request, HttpServletResponse response)
    {
        //获取输入的验证码
        String vCode=request.getAttribute("verifyCode").toString();
        try
        {
            PrintWriter pw=new PrintWriter(response.getOutputStream());
            //输入的验证码和生成的验证码进行比较,看是否相同,相同打印1，不同打印0
            if (request.getSession().getAttribute("rand").toString().equals(vCode))
            {
                pw.write("1");
            }
            else
            {
                pw.write("0");
            }            
            pw.close();
        }
        catch(java.io.IOException e)
        {
            e.printStackTrace();
        }        
        return "success";
    }
}