阿翔编程学-Java Servlet验证码的输出

package com.jxsafe.source.common.applications.source.classinfo.random;

import javax.servlet.*;
import javax.servlet.http.*;

import java.io.*;

import java.util.*;

import com.jxsafe.source.common.applications.source.classinfo.random.imp.IAuthImg;

import com.sun.image.codec.jpeg.*;

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

import org.apache.commons.lang.*;

/**
 * 验证码
 * @author CaoXiang
 * @version 1.0
 */
@SuppressWarnings("serial")
public class AuthImg extends HttpServlet implements IAuthImg {
 
 /**
  * 字符设置
  */
 @SuppressWarnings("unused")
 private static final String CONTENT_TYPE = "text/html; charset=GBK";

 /**
  * 字体设置
  */
 private Font mFont = new Font("Times New Roman", Font.PLAIN, 18);

 //Initialize global variables
 /* (non-Javadoc)
  * @see com.jxsafe.source.common.applications.source.classinfo.random.IAuthImg#init()
  */
 public void init() throws ServletException {
 }

 //Process the HTTP Get request
 /* (non-Javadoc)
  * @see com.jxsafe.source.common.applications.source.classinfo.random.IAuthImg#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
  */
 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  //设置应答流中的文本格式
  response.setContentType("image/jpeg");
  //获得输入类
  ServletOutputStream out = response.getOutputStream();
  //设置高度，宽度
  int width = 60, height = 20;
  //图片的字符流
  BufferedImage image = new BufferedImage(width, height,
    BufferedImage.TYPE_INT_RGB);
  //绘图对象
  Graphics g = image.getGraphics();
  //随即数
  Random random = new Random();
  //设置颜色
  g.setColor(getRandColor(200, 250));
  //绘制矩形
  g.fillRect(0, 0, width, height);
  //设置字体
  g.setFont(mFont);
  //设置颜色
  g.setColor(getRandColor(160, 200));
  //构建4个随即数,然后画条线
  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(30 + random.nextInt(120), 30 + random
     .nextInt(120), 30 + random.nextInt(120)));
   g.drawString(String.valueOf(c), 13 * i + 6, 16);
  }
  //获得Session对象
  HttpSession seesion = request.getSession();
  //保存图片到Session中
  seesion.setAttribute("authCode", rand);
  //输出到客户端
  JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
  encoder.encode(image);
  //关闭流
  out.close();
 }

 //Process the HTTP Post request
 /* (non-Javadoc)
  * @see com.jxsafe.source.common.applications.source.classinfo.random.IAuthImg#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
  */
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doGet(request, response);
 }

 //Clean up resources
 /* (non-Javadoc)
  * @see com.jxsafe.source.common.applications.source.classinfo.random.IAuthImg#destroy()
  */
 public void destroy() {
 }

 /**
  * 获得颜色对象
  * @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);
 }

}