Servlet生成彩色验证码

 

很早以前用的，为了防止忘记，做个记录

java 代码

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

import java.awt.*;
import java.awt.image.*;
import java.util.*;

public class ImageServlet
    extends HttpServlet {

  public void doGet(HttpServletRequest request, HttpServletResponse response) throws
      ServletException, IOException {
    response.reset();
    response.setContentType("image/jpeg");
    response.setHeader("Pragma", "No-cache");
    response.setHeader("Cache-Control", "no-cache");
    response.setDateHeader("Expires", 0);

//在内存中创建图象
    int width = 58, height = 18;
    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(new Color(201 + random.nextInt(50), 201 + random.nextInt(50),
                         201 + random.nextInt(50)));
    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(new Color(160 + random.nextInt(41), 160 + random.nextInt(41),
                         160 + random.nextInt(41)));
    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);
    }

//取随机产生的认证码(4位数字)
    String sRand = "";
    for (int i = 0; i < 4; i++) {
      String rand = String.valueOf(random.nextInt(10));
      sRand += rand;

//将认证码显示到图象中
      g.setColor(new Color(20 + random.nextInt(111), 20 + random.nextInt(111),
                           20 + random.nextInt(111)));

//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
      g.drawString(rand, 13 * i + 6, 16);
    }
    HttpSession session = null;

    session = request.getSession(true);

    //将认证码存入SESSION
    session.setAttribute("rand", sRand);

//图象生效
    g.dispose();

//输出图象到页面
//ImageIO.write(image, "JPEG", resp.getOutputStream());
//response.setContentType("image/jpeg");
    ServletOutputStream out = response.getOutputStream();
    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
    encoder.encode(image);
    out.close();
  }
}

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• 2007-04-19 11:18
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