xsi="http:
//www.w3.org/2001/XMLSchema-instance"xmlns="http:
//xmlns.jcp.org/xml/ns/javaee"xsi:
schemaLocation="http:
//xmlns.jcp.org/xml/ns/javaeehttp:
//xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"id="WebApp_ID"version="3.1">
libraryproject
index.html
index.htm
index.jsp
default.html
default.htm
default.jsp
getSession
servlet.getSession
session1
servlet.session1
getSession
/second
session1
/first
TextHttpServlet.java
packageservlet;
importjava.io.IOException;
importjava.text.DateFormat;
importjava.text.SimpleDateFormat;
importjava.util.Calendar;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importjavax.servlet.http.HttpSession;
publicclasstextHttpServletextendsHttpServlet{
@Override
protectedvoiddoGet（HttpServletRequestreq,HttpServletResponseresp）throwsServletException,IOException{
//TODOAuto-generatedmethodstub
this.doPost（req,resp）;
}
@Override
protectedvoiddoPost（HttpServletRequestreq,HttpServletResponseresp）throwsServletException,IOException{
//TODOAuto-generatedmethodstub
DateFormatformatter=newSimpleDateFormat（"yyyy-MM-ddhh:
mm:
ss"）;
Calendarcalendar=Calendar.getInstance（）;
HttpSessionsession=req.getSession（）;
System.out.println（"Session的ID为"+session.getId（））;
calendar.setTimeInMillis（session.getCreationTime（））;
System.out.println（"Session创建的时间为"+formatter.format（calendar.getTime（）））;
calendar.setTimeInMillis（session.getLastAccessedTime（））;
System.out.println（"Session最后活动的时间为"+formatter.format（calendar.getTime（）））;
System.out.println（"当前Session是否为新？
"+session.isNew（））;
System.out.println（"Session默认的活动时间为"+session.getMaxInactiveInterval（）/60+"分钟"）;
}
}
textHttpServlet
servlet.textHttpServlet
textHttpServlet
/three
一次性验证码
CheckedImgServlet.java
packageservlet;
importjava.awt.Color;
importjava.awt.Font;
importjava.awt.Graphics;
importjava.awt.Graphics2D;
importjava.awt.image.BufferedImage;
importjava.io.IOException;
importjava.util.Random;
importjavax.imageio.ImageIO;
importjavax.servlet.ServletException;
importjavax.servlet.annotation.WebServlet;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
@WebServlet（"/checkimg"）/*@只有一个不能是/xxx/的路径名只对应一个*/
publicclassCheckImgServletextendsHttpServlet{
privateGraphicsgraphics2;
@Override
protectedvoiddoGet（HttpServletRequestreq,HttpServletResponseresp）throwsServletException,IOException{
//TODOAuto-generatedmethodstub
this.doPost（req,resp）;
}
@Override
protectedvoiddoPost（HttpServletRequestreq,HttpServletResponseresp）throwsServletException,IOException{
//TODOAuto-generatedmethodstub
intwidth=120;
intheight=30;
BufferedImagebufferedImage=newBufferedImage（width,height,BufferedImage.TYPE_INT_RGB）;
Graphicsgraphics=bufferedImage.getGraphics（）;
graphics.setColor（getRandColor（200,250））;
graphics.fillRect（0,0,width,height）;
graphics.setColor（Color.WHITE）;
graphics.drawRect（0,0,width-1,height-1）;
Graphics2Dgraphics2d=（Graphics2D）graphics;
graphics2d.setFont（newFont（"宋体",Font.BOLD,18））;
Stringwords="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
Randomrandom=newRandom（）;
StringBufferbuffer=newStringBuffer（）;
intx=10;
for（inti=0;i<4;i++）{
graphics2d.setColor（newColor（20+random.nextInt（110）,20+random.nextInt（110）,20+random.nextInt（110）））;
intjiaodu=random.nextInt（60）-30;
doubletheta=jiaodu*Math.PI/180;
intindex=random.nextInt（words.length（））;
charc=words.charAt（index）;
buffer.append（c）;
graphics2d.rotate（theta,x,20）;
graphics2d.drawString（String.valueOf（c）,x,20）;
graphics2d.rotate（-theta,x,20）;
x+=30;
}
req.getSession（）.setAttribute（"checkcode_session",buffer.toString（））;
graphics.setColor（getRandColor（160,200））;
intx1;
intx2;
inty1;
inty2;
for（inti=0;i<30;i++）{
x1=random.nextInt（width）;
x2=random.nextInt（12）;
y1=random.nextInt（height）;
y2=random.nextInt（12）;
graphics.drawLine（x1,y1,x1+x2,x2+y2）;
}
graphics.dispose（）;
ImageIO.write（bufferedImage,"jpg",resp.getOutputStream（））;
}
/**
*取其某一范围的color
*@paramfc
*
*@parambc
*@returnColor
*/
privateColorgetRandColor（intfc,intbc）{
//TODOAuto-generatedmethodstub
Randomrandom=newRandom（）;
if（fc>255）{
fc=255;
}
if（bc>255）{
bc=255;
}
intr=fc+random.nextInt（bc-fc）;
intg=fc+random.nextInt（bc-fc）;
intb=fc+random.nextInt（bc-fc）;
returnnewColor（r,g,b）;
}
}
LoginServlet.java
packageservlet;
importjava.io.IOException;
importjavax.servlet.ServletException;
importjavax.servlet.annotation.WebServlet;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
@WebServlet（"/login"）
publicclassLoginServletextendsHttpServlet{
@Override
protectedvoiddoGet（HttpServletRequestreq,HttpServletResponseresp）throwsServletException,IOException{
//TODOAuto-generatedmethodstub
this.doPost（req,resp）;
}
@Override
protectedvoiddoPost（HttpServletRequestreq,HttpServletResponseresp）throwsServletException,IOException{
//TODOAuto-generatedmethodstub
req.setCharacterEncoding（"utf-8"）;
Stringusername=req.getParameter（"username"）;
Stringpassword=req.getParameter（"password"）;
Stringcheckcode=req.getParameter（"checkcode"）;
Stringcheckcode_session=（String）req.getSession（）.getAttribute（"checkcode_session"）;
req.getSession（）.removeAttribute（"checkcode_session"）;
if（checkcode_session==null||!
checkcode_session.equals（checkcode））{
req.setAttribute（"msg","验证码错误"）;
req.getRequestDispatcher（"login.jsp"）.forward（req,resp）;
return;
}
if（"admin".equals（username）&&"admin".equals（password））{
req.getSession（）.setAttribute（"username",username）;
resp.sendRedirect（"/yzm/welcome.jsp"）;
}else{
req.setAttribute（"msg","用户名或密码错误"）;
req.getRequestDispatcher（"login.jsp"）.forward（req,resp）;
}
}
}
Login.jsp
<%@pagelanguage="java"contentType="text/html;charset=UTF-8"
pageEncoding="UTF-8"%>
DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//EN""http:
//www.w3.org/TR/html4/loose.dtd">
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