servlet产生数字验证码

servlet产生数字验证码

package com.sun.test;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import    java.io.*;    
import    java.util.*;    
import    com.sun.image.codec.jpeg.*;    
import    javax.servlet.*;    
import    javax.servlet.http.*;    
import    java.awt.*;    
import    java.awt.image.*;    
public class getImg extends HttpServlet {
private    Font    mFont=new    Font("宋体",    Font.PLAIN,12);//设置字体  
/**
   * Constructor of the object.
   */
public getImg() {
   super();
}

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

public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
   response.setContentType("text/html");
   //PrintWriter out = response.getWriter();
    //取得一个1000-9999的随机数    
     String    s="";         
     int    intCount=0;          
     intCount=(new    Random()).nextInt(9999);//返回一个伪随机数，它是从此随机数生成器的序列中取出的、在 0（包括）和9999（不包括）之间均匀分布的 int值。          
     if(intCount<1000)intCount+=1000;          
     s=intCount+"";                
     //对session付值。          
     HttpSession    session=request.getSession(true);          
     session.setAttribute("getImg",s);          
     response.setContentType("image/gif");         
     ServletOutputStream    out=response.getOutputStream();          
     BufferedImage    image=new    BufferedImage(35,14,BufferedImage.TYPE_INT_RGB);          
     Graphics    gra=image.getGraphics();    
     //设置背景色    
     gra.setColor(Color.yellow);          
     gra.fillRect(1,1,33,12);    
     //设置字体色    
     gra.setColor(Color.black);          
     gra.setFont(mFont);    
     //输出数字    
     char    c;          
     for(int    i=0;i<4;i++)    {          
     c=s.charAt(i);          
     gra.drawString(c+"",i*7+4,11);    //7为宽度，11为上下高度位置          
     }          
     JPEGImageEncoder    encoder=JPEGCodec.createJPEGEncoder(out);          
     encoder.encode(image);          
     out.close();    
     }
 
public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
   doGet(request,response);    
 
}
public void init() throws ServletException {
   // Put your code here
}

}