Java 验证码

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CodeServlet.java

package org.zbq.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.OutputStream;
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;

public class CodeServlet extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		execute(req, resp);
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		execute(req, resp);
	}
	
	private void execute(HttpServletRequest req, HttpServletResponse resp){
		resp.setHeader("Pragma", "No-cache");  
		resp.setHeader("Cache-Control", "no-cache");  
		resp.setDateHeader("Expires", 0);  
		resp.setContentType("image/jpeg"); 
		
		int width = 80; //图片宽度
		int height = 35; // 图片高度
		
		//内存中创建图像
		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();
		Random random = new Random();//创建随即类
		g.setColor(Color.WHITE);//设置背景色
		g.fillRect(0, 0, width, height); //填充指定矩形
		
		g.setColor(Color.GRAY);//设置边框颜色
		g.drawRect(0, 0, width - 1, height - 1);
		//随机产生5条干扰线
		g.setColor(Color.BLACK);
		for(int i=0; i<5; i++){
			int x1 = random.nextInt(width);
			int y1 = random.nextInt(height);
			int x2 = random.nextInt(width);
			int y2 = random.nextInt(height);
			g.drawLine(x1, y1, x2, y2);
		}
		
		//随机产生100个点
		g.setColor(Color.GREEN);
		for(int i=0;i<100;i++){
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			g.drawLine(x, y, x, y);
		}
		
		//创建字体
		Font font = new Font(null, Font.ITALIC, 24);
		g.setColor(Color.RED);
		g.setFont(font);
		int length = 4; //4位的验证码
		String s = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
		String srand = "";
		for(int i=0; i<length; i++){
			String ch = String.valueOf(s.charAt(random.nextInt(s.length())));
			srand += ch;
			g.drawString(ch, 18*i+8, (random.nextInt(5)-2)*i+25);
		}
		System.out.println(srand);
		g.dispose();
		
		try {
			OutputStream out = resp.getOutputStream();
			ImageIO.write(image, "jpeg", out);
			out.flush();
			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>	
  
  <servlet>
  	<servlet-name>codeServlet</servlet-name>
  	<servlet-class>org.zbq.servlet.CodeServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
  	<servlet-name>codeServlet</servlet-name>
  	<url-pattern>/servlet/code</url-pattern>
  </servlet-mapping>
</web-app>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	<script type="text/javascript" src="js/jquery-1.7.2.js"></script>
	<script type="text/javascript">
		$().ready(function(){
			$("#change").click(function(){
				$("#code").attr("src",'${pageContext.request.contextPath}/servlet/code?'+Math.random()*10);
				return false;
			});
		});
	</script>
  </head>
  
  <body>
    <img alt="hello" id="code" src="<%=request.getContextPath()%>/servlet/code">
    <a href="#" id="change">看不清，换一张</a>
    <div id="d">123</div>
  </body>
</html>

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