今天闲的没事儿干. 就看着书实现了基于Servlet验证码功能.
不试不知道,一试才发现.垃圾玩意儿太繁琐.废话不多说直接上代码与图
package com;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageDecoder;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
import com.sun.jndi.url.corbaname.corbanameURLContextFactory;
public class servletFirst extends HttpServlet {
private static final long serialVersionUID = 1L;
public static final char[] CHARS = { '1', '2', '3', '4', '5', '6', '7',
'8', '9', '0', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', };
public static Random random = new Random();
public static String getRandomString() {
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < 9; i++) {
buffer.append(CHARS[random.nextInt(CHARS.length)]);
}
return buffer.toString();
}
public static Color getRandomColor() {
return new Color(random.nextInt(255), random.nextInt(255), random
.nextInt(255));
}
public static Color getReverseColor(Color c) {
return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c
.getBlue());
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");
String radomString = getRandomString();
request.getSession(true).setAttribute("radomString", radomString);
Color color = getRandomColor();
Color reverse = getReverseColor(color);
BufferedImage bi = new BufferedImage(100, 30, BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
g.setFont(new Font(Font.SANS_SERIF,Font.BOLD,16));
g.setColor(color);
g.fillRect(0,0,100,30);
g.setColor(reverse);
g.drawString(radomString,18,20);
for (int i = 0,n = random.nextInt(100); i<n; i++) {
g.drawRect(random.nextInt(100), random.nextInt(30), 1, 1);
}
ServletOutputStream out = response.getOutputStream();
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(bi);
out.flush();
}
}
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<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>
function reloadImage(){
document.getElementById("btn").disabled=true;
document.getElementById("imgservlet").src='servlet/servletFirst?ts='+new Date().getTime();
}
</script>
</head>
<body>
<img src="servlet/servletFirst" id="imgservlet" onload="btn.disabled=false;" onclick="reloadImage()""/>
<input type="button" value="换张图片" onclick="reloadImage()" id="btn">
</body>
</html>
以上就是核心代码.有兴趣的朋友可以看看