import javax.servlet.http.*;
public class SessionCounter implements HttpSessionListener {
private static int activeSessions = 0;
public void sessionCreated(HttpSessionEvent se) {
activeSessions++;
}
public void sessionDestroyed(HttpSessionEvent se) {
if(activeSessions > 0)
activeSessions--;
}
public static int getActiveSessions() {
return activeSessions;
}
}
鐒跺悗閰嶇疆web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
****************************************
<!-- Listeners -->
<listener>
<listener-class>
SessionCount.SessionCounter (娉ㄦ剰姝ゅ)
</listener-class>
</listener>
*****************************************
</web-app>
寤轟釜JSP嫻嬭瘯:
test.jsp
<%@ page language="Java" contentType="text/html;charset=GBK"%>
<%@ page import="java.sql.*"%>
<%@ page import="SessionCount.SessionCounter" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>鏃犳爣棰樻枃妗?lt;/title>
<body bgcolor="#FFFFFF">
鍦ㄧ嚎浜烘暟:<%=SessionCounter.getActiveSessions()%>
</body>
</html>
鐪嬬湅鍙互瀹炵幇涓?鎴戜篃鏄壘鍒扮殑,鎴戠敤浜?鍙互緇熻鍑烘潵.
]]>
涓嬮潰鏄敓鎴愮殑鍥劇墖錛?br />
浠ｇ爜濡備笅錛孞SP浠ｇ爜
<%@page pageEncoding="UTF-8"%>
<%@ page import="java.awt.*,javax.imageio.*,java.io.*,java.util.*,java.awt.image.*" %>
<%--
The taglib directive below imports the JSTL library. If you uncomment it,
you must also add the JSTL library to the project. The Add Library
actionon Libraries node in Projects view can be used to add the JSTL 1.1 library.
--%>
<%--
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
--%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%!String s="";%>
<%
java.util.List<String> fonts=new ArrayList<String>();
GraphicsEnvironment.getLocalGraphicsEnvironment().preferLocaleFonts();
String[] names=GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames(Locale.CHINA);
for(String s:names){
char c=s.charAt(0);
if(Character.isLowerCase(c)||Character.isUpperCase(c)){
}else{
fonts.add(s);
}
}
BufferedImage bi=new BufferedImage(200,50,BufferedImage.TYPE_INT_RGB);
Graphics2D g=bi.createGraphics();
char[] cs={'0','1','2','3','4','5','6','7','8','9'};
char[] use=new char[4];
g.setColor(new Color(240,240,240));
g.fillRect(0,0,200,50);
for(int i=0;i<4;i++){
Point p=new Point(5+(i*((int)(Math.random()*10)+40)),40);
int size=0;
int[] sizes=new int[20];
for(int j=0;j<20;j++){
sizes[j]=30+j;
}
size=sizes[(int)(Math.random()*sizes.length)];
int face=0;
if(Math.random()*10>5){
face=Font.BOLD;
}else{
face=Font.ITALIC;
}
use[i]=cs[(int)(Math.random()*cs.length)];
g.setPaint(new GradientPaint(p.x,p.y,new Color((int)(Math.random()*256),0,(int)(Math.random()*256)),
p.x,p.y-size,new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256))));
g.setFont(new Font(fonts.get((int)(Math.random()*fonts.size())),face,size));
g.drawString(""+use[i],p.x,p.y);
}
s=new String(use);
session.setAttribute("code", s);
g.setPaint(null);
for(int i=0;i<4;i++){
g.setColor(new Color((int)(Math.random()*0x00FFFFFFF)));
g.drawLine((int)(Math.random()*200),(int)(Math.random()*50),(int)(Math.random()*200),(int)(Math.random()*50));
}
Random random = new Random();
for (int i=0;i<88;i++) {
int x = random.nextInt(200);
int y = random.nextInt(50);
g.setColor(new Color((int)(Math.random()*0x00FFFFFFF)));
g.setStroke(new BasicStroke((float)(Math.random()*3)));
g.drawLine(x,y,x,y);
}
OutputStream ot=response.getOutputStream();
ImageIO.write(bi,"JPEG",ot);
g.dispose();
ot.close();
%>
* Code.java
*
* Created on 2007騫?鏈?1鏃? 涓嬪崍12:08
*/
package com.hadeslee;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.GraphicsEnvironment;
import java.awt.Paint;
import java.awt.Point;
import java.awt.Stroke;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.*;
import javax.servlet.http.*;
/**
*
* @author lbf
* @version
*/
public class Code extends HttpServlet {
/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
*/
private List<String> fonts=new ArrayList<String>();
public Code(){
initFonts();
}
private void initFonts(){
GraphicsEnvironment.getLocalGraphicsEnvironment().preferLocaleFonts();
String[] names=GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames(Locale.CHINA);
for(String s:names){
char c=s.charAt(0);
if(Character.isLowerCase(c)||Character.isUpperCase(c)){
}else{
fonts.add(s);
}
}
}
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg;charset=UTF-8");
OutputStream out=response.getOutputStream();
BufferedImage bi=new BufferedImage(200,50,BufferedImage.TYPE_INT_RGB);
Graphics2D g=bi.createGraphics();
char[] cs={'0','1','2','3','4','5','6','7','8','9'};
char[] use=new char[4];
g.setColor(new Color(240,240,240));
g.fillRect(0,0,200,50);
for(int i=0;i<4;i++){
Point p=getPoint(i);
int size=getSize();
use[i]=cs[(int)(Math.random()*cs.length)];
// g.setColor(new Color((int)(Math.random()*256),0,(int)(Math.random()*256)));
g.setPaint(getPaint(p,size));
g.setFont(new Font(fonts.get((int)(Math.random()*fonts.size())),getFace(),size));
g.drawString(""+use[i],p.x,p.y);
}
g.setStroke(new BasicStroke(1.0f));
g.setPaint(null);
for(int i=0;i<4;i++){
g.setColor(new Color((int)(Math.random()*0x00FFFFFFF)));
g.drawLine((int)(Math.random()*200),(int)(Math.random()*50),(int)(Math.random()*200),(int)(Math.random()*50));
}
Random random = new Random();
for (int i=0;i<88;i++) {
int x = random.nextInt(200);
int y = random.nextInt(50);
g.setColor(new Color((int)(Math.random()*0x00FFFFFFF)));
g.setStroke(getStroke());
g.drawLine(x,y,x,y);
}
ImageIO.write(bi,"JPEG",out);
out.close();
g.dispose();
}
private Stroke getStroke(){
BasicStroke bs=new BasicStroke((float)(Math.random()*3));
return bs;
}
private Point getPoint(int index){
return new Point(5+(index*((int)(Math.random()*10)+40)),40);
}
private Paint getPaint(Point p,int size){
GradientPaint gp=new GradientPaint(p.x,p.y,new Color((int)(Math.random()*256),0,(int)(Math.random()*256)),
p.x,p.y-size,new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256)));
return gp;
}
private int getFace(){
if(Math.random()*10>5){
return Font.BOLD;
}else{
return Font.ITALIC;
}
}
private int getSize(){
int[] sizes=new int[20];
for(int i=0;i<20;i++){
sizes[i]=30+i;
}
return sizes[(int)(Math.random()*sizes.length)];
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/** Handles the HTTP <code>GET</code> method.
* @param request servlet request
* @param response servlet response
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/** Handles the HTTP <code>POST</code> method.
* @param request servlet request
* @param response servlet response
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/** Returns a short description of the servlet.
*/
public String getServletInfo() {
return "Short description";
}
// </editor-fold>
}
鍦ㄨ繖閲屾垜浠厛寰楀埌浜嗘湇鍔″櫒鎵鍦ㄧ殑緋葷粺鐨勫瓧浣擄紝騫剁敤榪欎簺瀛椾綋鐢熸垚涓嶅悓鐨勫瓧絎︼紝鐒跺悗鍐嶉殢鏈鴻澶у皬錛岄殢鏈哄彉褰紝鐒跺悗涓哄瓧浣撳姞涓婃笎鍙橈紝騫剁粰鏁翠釜鍥劇墖娣誨姞騫叉壈綰挎潯浠ュ強騫叉壈鐐?璁╃▼搴忚瘑鍒殑闅懼害鍔犲ぇ.
鍛靛懙錛屾垜浠彲浠ユ妸瀹冩敼鎴愬瓧姣嶆垨鑰呬腑鏂囩殑楠岃瘉錛岄亾鐞嗛兘鏄竴鏍風殑錛屽彧涓嶈繃鍦ㄧ敓鎴愮殑鏃跺欙紝涓嶄竴瀹氱敤鏁板瓧浜嗭紝鑰屾槸鐢ㄦ墍鏈夊彲浠ヨ緭鍏ョ殑鏂囧瓧.榪欐牱錛岃紼嬪簭璇嗗埆鐨勫彲鑳藉張灝忎簡.
]]>
鍏蜂綋鐨勫疄鐜版儏鍐佃鐪嬫垜浠殑璁哄潧()鐨勯獙璇佺爜~~~~ http://bbs.8isp.cn
http://bbs.8isp.cn
鍏堟妸鎬濊礬璇翠笅: http://bbs.8isp.cn
http://bbs.8isp.cn
涓涓狫SP欏甸潰鎴栬匟TML欏甸潰(A.JSP)璋冪敤涓涓猄ERVLET鑰屽疄鐜伴獙璇佺爜,SERVLET璐熻矗鎶婂浘璞￠噷鐨勬暟瀛椾繚瀛樺埌SESSION涓?鍦↗SP鎴栬匟TML鐨勯〉闈腑鎶婂間紶閫掔粰B.jsp,B.JSP璐熻矗鎺ユ敹A浼犻掕繃鏉ョ殑鍊煎拰SESSION閲岀殑鍊煎仛姣旇緝濡傛灉涓鏍峰氨璇存槑鐢ㄦ埛杈撳叆姝ｇ‘鐨勯獙璇佺爜,濡傛灉涓嶄竴鏍峰氨榪斿洖涓敊璇? http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
濂戒簡鐜板湪鎴戜滑寮濮嬩簡,,, http://bbs.8isp.cn
http://bbs.8isp.cn
鍏堝啓涓猄ERVLET,娉ㄦ剰鍖呯殑璺緞鎴戠殑璺緞涓?WEB-INF\classes\dreamtime\dreamnews\ImageServlet.java http://bbs.8isp.cn
http://bbs.8isp.cn
鍏堢湅鐪嬭繖涓猄ERVLET:
package com.semovy.test;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class ImageServlet extends HttpServlet {
// 楠岃瘉鐮佸浘鐗囩殑瀹藉害銆?br> private int width=60;
//楠岃瘉鐮佸浘鐗囩殑楂樺害銆?br> private int height=20;
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, java.io.IOException
{
BufferedImage buffimg=new BufferedImage(width,height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g=buffimg.createGraphics();
//鍒涘緩涓涓殢鏈烘暟鐢熸垚鍣ㄧ被銆?br> Random random=new Random();
g.setColor(Color.white);
g.fillRect(0,0,width,height);
//鍒涘緩瀛椾綋錛屽瓧浣撶殑澶у皬搴旇鏍規嵁鍥劇墖鐨勯珮搴︽潵瀹氥?br> Font font=new Font("times new roman",Font.PLAIN,18);
//璁劇疆瀛椾綋銆?br> g.setFont(font);
//鐢昏竟妗嗐?br> g.setColor(Color.black);
g.drawRect(0,0,width-1,height-1);
//闅忔満浜х敓160鏉″共鎵扮嚎錛屼嬌鍥捐薄涓殑璁よ瘉鐮佷笉鏄撹鍏跺畠紼嬪簭鎺㈡祴鍒般?br> g.setColor(Color.gray);
for (int i=0;i<10;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
//randomcode鐢ㄤ簬淇濆瓨闅忔満浜х敓鐨勯獙璇佺爜錛屼互渚跨敤鎴風櫥褰曞悗榪涜楠岃瘉銆?br> StringBuffer randomcode=new StringBuffer();
int red=0,green=0,blue=0;
//闅忔満浜х敓4浣嶆暟瀛楃殑楠岃瘉鐮併?br> for (int i=0;i<4;i++)
{
//寰楀埌闅忔満浜х敓鐨勯獙璇佺爜鏁板瓧銆?br> String strrand=String.valueOf(random.nextInt(10));
//浜х敓闅忔満鐨勯鑹插垎閲忔潵鏋勯犻鑹插鹼紝榪欐牱杈撳嚭鐨勬瘡浣嶆暟瀛楃殑棰滆壊鍊奸兘灝嗕笉鍚屻?br> red=random.nextInt(200);
green=random.nextInt(200);
blue=random.nextInt(200);
//浜х敓闅忔満楂樺害 13鑷砲eight涔嬮棿
float imght = 0;
while(imght<=12){
imght = Float.parseFloat(String.valueOf(random.nextInt(height)));
}
//鐢ㄩ殢鏈轟駭鐢熺殑棰滆壊灝嗛獙璇佺爜緇樺埗鍒板浘鍍忎腑銆?br> g.setColor(new Color(red,green,blue));
g.drawString(strrand,13*i+6,imght);
//灝嗕駭鐢熺殑鍥涗釜闅忔満鏁扮粍鍚堝湪涓璧楓?br> randomcode.append(strrand);
}
//灝嗗洓浣嶆暟瀛楃殑楠岃瘉鐮佷繚瀛樺埌session涓?br> HttpSession session=req.getSession();
session.setAttribute("VerifyCode",randomcode.toString());
//紱佹鍥懼儚緙撳瓨銆?br> resp.setHeader("pragma","no-cache");
resp.setHeader("cache-control","no-cache");
resp.setDateHeader("expires", 0);
resp.setContentType("image/jpeg");
//灝嗗浘鍍忚緭鍑哄埌servlet杈撳嚭嫻佷腑銆?br> ServletOutputStream sos=resp.getOutputStream();
ImageIO.write(buffimg, "jpeg",sos);
sos.close();
}
}
SERVLET瀹屾瘯,娉ㄦ剰榪欏彞璇漵ession.setAttribute("VerifyCode",sRand);,鎴戞兂鏄仛JSP鐨勫簲璇ラ兘鐭ラ亾榪欎釜鏄粈涔堟剰鎬濆惂,瀵逛簡,榪欏彞璇濈殑鎰忔濆氨鏄妸鐢熸垚鍑烘潵鐨勬暟瀛椾繚瀛樺埌SESSION涓幓,鎴戜滑鍦ㄦ潵閰嶇疆涓媁EB.XML鏂囦歡鏉ヨ榪欎釜SERVLET鍙互鐢? http://bbs.8isp.cn
http://bbs.8isp.cn
WEB.XML濡備笅: http://bbs.8isp.cn
http://bbs.8isp.cn
<?xml version="1.0" encoding="UTF-8"?> http://bbs.8isp.cn
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" " http://java.sun.com/dtd/web-app_2_3.dtd "> http://bbs.8isp.cn
<web-app> http://bbs.8isp.cn
<servlet> http://bbs.8isp.cn
<servlet-name>Code</servlet-name> http://bbs.8isp.cn
<servlet-class>dreamtime.dreamnews.ImageServlet</servlet-class> http://bbs.8isp.cn
</servlet> http://bbs.8isp.cn
<servlet-mapping> http://bbs.8isp.cn
<servlet-name>Code</servlet-name> http://bbs.8isp.cn
<url-pattern>/Code</url-pattern> http://bbs.8isp.cn
</servlet-mapping> http://bbs.8isp.cn
</web-app> http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
榪欐牱榪欎釜SERVLET灝卞彲浠ョ敤浜?.. http://bbs.8isp.cn
http://bbs.8isp.cn
鎴戜滑鏉ョ湅A.HTM鎬庝箞璋冪敤榪欎釜SERVLET鏉ュ疄鐜伴獙璇佺爜: http://bbs.8isp.cn
http://bbs.8isp.cn
A.HTM濡備笅: http://bbs.8isp.cn
http://bbs.8isp.cn
<FORM ACTION=B.JSP NAME=FORM > http://bbs.8isp.cn
鐢ㄦ埛鍚?<input class=input maxlength=255 size=10 name=username> http://bbs.8isp.cn
瀵?鐮?<input class=input type=password maxlength=255 size=10 name=password> http://bbs.8isp.cn
http楠岃瘉鐮?<input name=image type=text value="璇峰湪榪欓噷杈撳叆鍙寵竟鐨勯獙璇佺爜" http://bbs.8isp.cn
size=7 maxlength=255> <img src="Code" onclick="history.go(0)" title="鐐瑰嚮鍒鋒柊楠岃瘉鐮?/> http://bbs.8isp.cn
</FORM> http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
A.HTM鐪嬭搗鏉ュ緢綆鍗?綰㈣壊鐨勫瓧鏄樉紺篠ERVLET鏉ヨ楠岃瘉鐮佸嚭鐜板湪緗戦〉涓妦~~鍏拌壊鐨勫瓧鏄釜璁╃敤鎴瘋緭鍏ラ獙璇佺爜鐨勫湴鏂?鍏跺疄灝辨槸涓櫘閫氱殑INPUT, http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
http://bbs.8isp.cn
鍦ㄦ潵鐪嬬湅B.JSP鏄浣曟帴鏀剁殑.... http://bbs.8isp.cn
http://bbs.8isp.cn
B.JSP濡備笅: http://bbs.8isp.cn
http://bbs.8isp.cn
String rand = (String)session.getAttribute("VerifyCode"); //鎻愬彇鏀懼湪SESSION鐨勬暟瀛? http://bbs.8isp.cn
String input = request.getParameter("image"); //鎺ユ敹浠嶢.HTM浼犻掕繃鏉ョ殑鍊?/font> http://bbs.8isp.cn
http://bbs.8isp.cn
if(!rand.equals(input)){ http://bbs.8isp.cn
out.println("楠岃瘉鐮佷笉瀵?); http://bbs.8isp.cn
http://bbs.8isp.cn
}else{ http://bbs.8isp.cn
http://bbs.8isp.cn
out.println("楠岃瘉鐮佹紜?) http://bbs.8isp.cn
http://bbs.8isp.cn
} http://bbs.8isp.cn
http://bbs.8isp.cn
]]>