圖形驗證碼Servlet實現
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* Servlet implementation class CheckCodeServlet
*/
@WebServlet("/CheckCodeServlet")
public class CheckCodeServlet extends HttpServlet {
public static final String CHECKCODE = "checkCode";// 放到session中的key
private Random random = new Random();
private static String CHECKCODES = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";// 隨機產生的字符串
private static int WIDTH= 60;// 圖片寬
private static int HEIGHT = 20;// 圖片高
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
this.doPost(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
HttpSession session = request.getSession();
response.setContentType("image/jpeg");
ServletOutputStream sos=response.getOutputStream();
//設置圖片不緩存
response.setHeader("progma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// BufferedImage類是具有緩衝區的Image類,Image類是用於描述圖像信息的類
BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
// 產生Image對象的Graphics對象,改對象可以在圖像上進行各種繪製操作
Graphics g = image.getGraphics();
char[] code=this.generateCheckCode();
this.drawBackground(g);
this.drowString(g, code);
g.dispose();
ByteArrayOutputStream bos=new ByteArrayOutputStream();
ImageIO.write(image, "jpeg", bos);
byte[] buf=bos.toByteArray();
response.setContentLength(buf.length);
sos.write(buf);
bos.close();
sos.close();
session.setAttribute(CHECKCODE, new String(code));
}
/*
* 繪製字符串
*/
private void drowString(Graphics g, char[] code) {
g.setColor(Color.BLACK);
g.setFont(new Font(null,Font.ITALIC|Font.BOLD,18));
g.drawString(""+code[0], 1, 17);
g.drawString(""+code[1], 16, 15);
g.drawString(""+code[2], 31, 18);
g.drawString(""+code[3], 46, 16);
}
/*
* 繪製干擾點
*/
private void drawBackground(Graphics g){
//畫背景
g.setColor(new Color(0xDCDCDC));
g.fillRect(0, 0, WIDTH, HEIGHT);
//隨機產生干擾點
for(int i=0;i<120;i++){
int x=(int)(Math.random()*WIDTH);
int y=(int)(Math.random()*HEIGHT);
int red=(int)(Math.random()*255);
int blue=(int)(Math.random()*255);
int green=(int)(Math.random()*255);
g.setColor(new Color(red,green,blue));
g.drawOval(x, y, 1, 0);
}
}
/*
* 獲取隨機的字符
*/
private char[] generateCheckCode() {
char code[]=new char[4];
for(int i=0;i<4;i++)
{
int n=(int)(Math.random()*62);
code[i]=CHECKCODES.charAt(n);
}
return code;
}
}
測試頁面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="" method="post">
<table>
<tr>
<td>name:</td>
<td><input type="text" id="name"/></td></tr>
<tr>
<td>SN:</td>
<td><input type="password" id="psw"></td></tr>
<tr>
<td><input type="submit" value="submit"></td>
<td><img src="getCheckCode"></td></tr>
</table>
</form>
</body>
</html>web.xml配置
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
<display-name></display-name>
<servlet>
<servlet-name>checkCode</servlet-name>
<servlet-class>com.control.CheckCodeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>checkCode</servlet-name>
<url-pattern>/getCheckCode</url-pattern>
</servlet-mapping>
</web-app>