authimg.java

一个jsp写的bbs

package com.laoer.bbscs.web.servlet;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import java.awt.*;
import java.awt.image.*;
import org.apache.commons.lang.*;

public class AuthImg
    extends HttpServlet {
  private static final String CONTENT_TYPE = "text/html; charset=UTF-8";

  private Font mFont = new Font("Times New Roman", Font.PLAIN, 18);

  //Initialize global variables
  public void init() throws ServletException {
  }

  //Process the HTTP Get request
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
      IOException {
    response.setContentType("image/jpeg");
    ServletOutputStream out = response.getOutputStream();

    int width = 60, height = 20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

    Graphics g = image.getGraphics();
    Random random = new Random();

    g.setColor(getRandColor(200, 250));
    g.fillRect(0, 0, width, height);

    g.setFont(mFont);

    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);
    }

    String rand = RandomStringUtils.randomNumeric(4);
    char c;
    for (int i = 0; i < 4; i++) {
      c = rand.charAt(i);
      g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110))); //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(String.valueOf(c), 13 * i + 6, 16);
    }
    HttpSession seesion = request.getSession();
    seesion.setAttribute("authCode", rand);
    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
    encoder.encode(image);
    out.close();
  }

  //Process the HTTP Post request
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,
      IOException {
    doGet(request, response);
  }

  //Clean up resources
  public void destroy() {
  }

  private Color getRandColor(int fc, int bc) { //给定范围获得随机颜色
    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);
  }

}