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
}

}