jpegservlet.java

通讯录

package cn.com.txl.servlet;

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.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class JPEGServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public JPEGServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	 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);
     }

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("image/jpeg");
		response.setHeader("Pragma","No-cache");
		response.setHeader("Cache-Control","no-cache");
		response.setDateHeader("Expires", 0);
        HttpSession session = request.getSession();
        
        // 在内存中创建图象
        int width=60, 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("Terminal",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<15;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="";
        String a[] = {"1","2","3","4","5","6","7","8","9","0","K"};
        for (int i=0;i<4;i++)
        {
            String rand=a[random.nextInt(10)];
            sRand+=rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20+random.nextInt(30),20+random.nextInt(30),20+random.nextInt(30)));
                // 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,15*i+6,16);
        }
        
        // 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", response.getOutputStream());
        //JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(res.getOutputStream());
        //encoder.encode(image);

	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out
				.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");
		out.print("    This is ");
		out.print(this.getClass());
		out.println(", using the POST method");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occure
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}