Servlet编程-步步为营

【环境】
eclipse j2ee;
Tomcat 7.0;

【模型1】

package com.zhiqi;

import ...;

public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	public void doGet(HttpServletRequest 

req,HttpServletResponse resp) throws 

ServletException,IOException{
		resp.setContentType

("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>test 

Servlet</title></head>");
		out.println("<body>");
		out.println("欢迎使用Servlet编程");
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
	<servlet>
		<servlet-name>TestServlet</servlet-name>
		<servlet-

class>com.zhiqi.TestServlet</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>TestServlet</servlet-name>
		<url-pattern>/fun</url-pattern>
	</servlet-mapping>
</web-app>

　　【模型2】getInitParameter("repeat")

package com.zhiqi;

import ...;

public class SecondServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest 

req,HttpServletResponse resp) throws 

ServletException,IOException{
		int repeat=Integer.parseInt

(getInitParameter("repeat"));
		resp.setContentType

("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>test2 

Servlet</title></head>");
		out.println("<body>");
		
		for(int i=0;i<repeat;i++){
			out.println("<table border=

"1"><tr>");
			out.println("<td>"+(i

+1)+"</td><td>");
			out.println("欢迎使用Servlet");
			out.println

("</td></tr></table>");
			out.println("<br>");
		}
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
	<servlet>
		<servlet-name>SecondServlet</servlet-

name>
		<servlet-

class>com.zhiqi.SecondServlet</servlet-class>
		
		<init-param>
			<param-name>repeat</param-name>
			<param-value>5</param-value>
		</init-param>
	</servlet>

	<servlet-mapping>
		<servlet-name>SecondServlet</servlet-

name>
		<url-pattern>/second</url-pattern>
	</servlet-mapping>
</web-app>

　　【模型3】获取服务器的运行参数

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ThirdServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		doPost(req,resp);
	}
	
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		resp.setContentType("text/html;charset=utf-8");		
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>test3 Servlet</title></head>");
		out.println("<body>");
		fun(req,out);
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
	public void fun(HttpServletRequest req,PrintWriter out)  throws IOException{
		out.println("<ul>");
		out.println("<li>服务器IP->"+req.getRemoteAddr()+"</li>");
		out.println("<li>服务器名->"+req.getServerName()+"</li>");
		out.println("<li>服务器端口->"+req.getServerPort()+"</li>");
		out.println("<li>协议名->"+req.getScheme()+"</li>");
		out.println("<li>协议版本->"+req.getProtocol()+"</li>");
		out.println("<li>请求的方法->"+req.getMethod()+"</li>");
		out.println("<li>请求的URL->"+req.getRequestURL()+"</li>");
		out.println("<li>上下文路径->"+req.getContextPath()+"</li>");
		out.println("<li>Servlet路径->"+req.getServletPath()+"</li>");
		
		out.println("</ul>");
	}
}

<?xml version="1.0" encoding="UTF-8"?>

<web-app>
	<servlet>
		<servlet-name>ThirdServlet</servlet-name>
		<servlet-class>com.zhiqi.ThirdServlet</servlet-class>
		
	</servlet>

	<servlet-mapping>
		<servlet-name>ThirdServlet</servlet-name>
		<url-pattern>/third</url-pattern>
	</servlet-mapping>
</web-app>

【模型4】获得头信息

package com.zhiqi;

import ...

public class FourthServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		fun(req,resp);
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		fun(req,resp);
	}
	public void fun(HttpServletRequest req,HttpServletResponse resp)throws ServletException,IOException{
		String headers=null;
		Enumeration e=req.getHeaderNames();
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>test4 Servlet</title></head>");
		out.println("<body>");
		out.println("<ul>");

		while(e.hasMoreElements()){
			headers=(String) e.nextElement();
			if(headers!=null){
				out.println("<li>"+headers+" -> "+req.getHeader(headers)+"</li>");
				//out.println("->");
				//out.println("<li>"+req.getHeader(headers)+"</li>");
			}
		}
		//out.println("<li>"+"</li>");
		out.println("</ul>");
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
}

<?xml version="1.0" encoding="UTF-8"?>

<web-app>
	<servlet>
		<servlet-name>FourthServlet</servlet-name>
		<servlet-class>com.zhiqi.FourthServlet</servlet-class>
		
	</servlet>

	<servlet-mapping>
		<servlet-name>FourthServlet</servlet-name>
		<url-pattern>/fourth</url-pattern>
	</servlet-mapping>
</web-app>

　【模型5】Servlet处理表单

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>login</title></head>");
		out.println("<body>");
		out.println("<h2>请输入登录信息</h2>");
		out.println("<form method='post' action='"+req.getContextPath()//上下文路径
				+"/f'"		
				+"'>");
		out.println("<div>用户名：</div>");
		out.println("<div><input type='text' name='userName' id='userName' /></div>");
		
		out.println("<div>密码：</div>");
		out.println("<div><input type='password' name='password' id='password' /></div>");
		
		out.println("<div><input type='submit' value='提交' /></div></form>");
		
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		req.setCharacterEncoding("utf-8");//解决提交的表单数据中文乱码
		out.println("<html>");
		out.println("<head><title>login info</title></head>");
		out.println("<body>");
		String userName=req.getParameter("userName");
		String password=req.getParameter("password");
		if(userName==null || userName.length()==0 || password==null || password.length()==0){
			out.println("<h2>输入用户名和密码</h2>");
			out.println("<br><a href='"
			+req.getContextPath()+"/f'"
			+">登录</a>");		
		}else{
			out.println("<h2>用户信息</h2>");
			out.println(userName);
			out.println(password);
		}
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
		
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>

	<servlet>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>com.zhiqi.LoginServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/f</url-pattern>
	</servlet-mapping>

</web-app>

通过Servlet处理表单是非常麻烦的，1、需要调用out对象输出。2、双引号的转义

所以需要对此进行改造

模型【6】处理HTML页面的表单

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>login page</title>
</head>
<body>
<h3>请输入用户名和密码</h3>
<div>
<form method="post" action="/LoginServlet2/f"><!-- 上下文路径+url-pattern -->
用户名：<input type="text" name="userName" ><br><br>
密码：<input type="password" name="password" ><br><br>
<input type="submit" value="登录">
</form>
</div>

</body>
</html>

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet2 extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>login</title></head>");
		out.println("<body>");
		out.println("<h2>请输入登录信息</h2>");
		out.println("<form method='post' action='"+req.getContextPath()//上下文路径
				+"/f'"		
				+"'>");
		out.println("<div>用户名：</div>");
		out.println("<div><input type='text' name='userName' id='userName' /></div>");
		
		out.println("<div>密码：</div>");
		out.println("<div><input type='password' name='password' id='password' /></div>");
		
		out.println("<div><input type='submit' value='提交' /></div></form>");
		
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		req.setCharacterEncoding("utf-8");//解决提交的表单数据中文乱码
		out.println("<html>");
		out.println("<head><title>login info</title></head>");
		out.println("<body>");
		String userName=req.getParameter("userName");
		String password=req.getParameter("password");
		if(userName==null || userName.length()==0 || password==null || password.length()==0){
			out.println("<h2>输入用户名和密码</h2>");
			out.println("<br><a href='"
			+req.getContextPath()+"/f'"
			+">登录</a>");		
		}else{
			out.println("<h2>用户信息</h2>");
			out.println(userName);
			out.println(password);
		}
		out.println("</body>");
		out.println("</html>");
		out.flush();
		out.close();
		
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>

	<servlet>
		<servlet-name>LoginServlet2</servlet-name>
		<servlet-class>com.zhiqi.LoginServlet2</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>LoginServlet2</servlet-name>
		<url-pattern>/f</url-pattern>
	</servlet-mapping>

</web-app>

【模型7】实例-网络调查表

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>网络调查表</title>
</head>
<body>
<h2>潜在用户调查</h2>
<div>
<form method="post" action="/Example1/f">
<div>
	<div style="float:left;margin-left:50px;">姓名：</div>
	<div style="float:left;margin-left:20px;"><input type="text" name="name"></div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;">Email：</div>
	<div style="float:left;margin-left:20px;margin-top:5px;"><input type="text" name="email"></div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;">年龄：</div>
	<div style="float:left;margin-left:20px;margin-top:5px;">
		<input type="radio" name="age" value="小于18">小于18
		<input type="radio" name="age" value="18-25">18-25
		<input type="radio" name="age" value="26-40">26-40
		<input type="radio" name="age" value="大于40">大于40
	</div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;">编程时间：</div>
	<div style="float:left;margin-left:50px;margin-top:5px;">
		<select name="seltime">
			<option value="1-2年">1-2年</option>
			<option value="2-5年">2-5年</option>
			<option value="5-10年">5-10年</option>
		</select>
	</div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;">使用操作系统：</div>
	<div style="float:left;margin-left:20px;margin-top:5px;">
		<select name="selos">
			<option value="Win XP">Win XP</option>
			<option value="Linux">Linux</option>
			<option value="Mac OS">Mac OS</option>
		</select>
	</div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;">使用编程语言：</div>
	<div style="float:left;margin-left:20px;margin-top:5px;">
		<input type="checkbox" name="lan" value="C">C
		<input type="checkbox" name="lan" value="C++">C++
		<input type="checkbox" name="lan" value="JAVA">JAVA
		<input type="checkbox" name="lan" value="C#">C#
		<input type="checkbox" name="lan" value="Python">Python
	</div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;">建议：</div>
	<div style="float:left;margin-left:20px;margin-top:5px;">
		<textarea name="ta"></textarea>
	</div>
</div>
<div style="clear:both;">
	<div style="float:left;margin-left:50px;margin-top:5px;"></div>
	<div style="float:left;margin-left:20px;margin-top:5px;">
		<input type="reset" name="" value="重置">
		<input type="submit" name="" value="提交">
	</div>
</div>

</form>
</div>
</body>
</html>

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Example1 extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		doPost(req,resp);
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		req.setCharacterEncoding("utf-8");
		out.println("<html>");
		out.println("<head><title>网络调查</title></head>");
		out.println("<body>");
		
		out.println("<h3>用户出入了以下信息</h3>");
		
		String name=req.getParameter("name");
		out.println("<p>用户姓名："+name+"</p>");
		String email=req.getParameter("email");
		out.println("<p>用户邮箱："+email+"</p>");
		String age=req.getParameter("age");
		out.println("<p>用户年龄："+age+"</p>");
		String seltime=req.getParameter("seltime");
		out.println("<p>编程时间："+seltime+"</p>");
		String selos=req.getParameter("selos");
		out.println("<p>使用平台："+selos+"</p>");
		
		String [] lan=req.getParameterValues("lan");//获取数组
		out.println("<p>使用编程语言</p><ul>");
		for(int i=0;i<lan.length;i++){
			out.println("<li>"+lan[i]+"</li>");
		}
		out.println("</ul>");
		
		String ta=req.getParameter("ta");
		out.println("<p>建议："+ta+"</p>");
		out.println("</body>");
		out.println("</html>");
	}
}

<?xml version="1.0" encoding="UTF-8"?>

<web-app>

	<servlet>
		<servlet-name>Example1</servlet-name>
		<servlet-class>com.zhiqi.Example1</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>Example1</servlet-name>
		<url-pattern>/f</url-pattern>
	</servlet-mapping>

</web-app>

　　运行

【模型8】枚举类型获取参数以及参数值

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>满意度调查</title>
</head>
<body>
<h3>枚举类型获取参数以及参数值</h3>
<h3>你对本网站提供的内容满意吗？</h3>

<form method="post" action="/Example2/f">
<input type="hidden" name="reach_reco" value="满意度调查">
<input type="submit" name="subm_cho" value="满意">
<input type="submit" name="subm_cho" value="不满意">
</form>

</body>
</html>

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Example2 extends HttpServlet {
	
	private static final long serialVersionUID = 1L;
	
	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		doPost(req,resp);
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		req.setCharacterEncoding("utf-8");
		out.println("<html>");
		out.println("<head><title>网络调查</title></head>");
		out.println("<body>");
		out.println("<h3>信息如下</h3>");
		
		//获取枚举类型,可在不知道参数名的情况下输出
		Enumeration e=req.getParameterNames();
		while(e.hasMoreElements()){
			String str=(String) e.nextElement();
			out.println("<p>"+str+"</p>");
			
			String [] s=req.getParameterValues(str);
			for(int i=0;i<s.length;i++){
				out.println("<p>"+s[i]+"</p>");
			}
		}
		
		out.println("</body>");
		out.println("</html>");
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
 
    <servlet>
        <servlet-name>Example2</servlet-name>
        <servlet-class>com.zhiqi.Example2</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Example2</servlet-name>
        <url-pattern>/f</url-pattern>
    </servlet-mapping>
 
</web-app>

【模型9】Cookie的使用

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Test Cookie</title>
</head>
<body>

<h3>Test Cookie</h3>
<form method="post" action="/Example8/set">
用户名：<input type="text" name="userName" id="userName" />
<br><br>
<input type="submit" value="登录" />
<input type="reset" value="重置" />
</form>
</body>
</html>

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Test_setCookie extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		doPost(req,resp);
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		req.setCharacterEncoding("utf-8");
		out.println("<html>");
		out.println("<head><title>Test Cookie</title></head>");
		out.println("<body>");
		
		out.println("<h3>测试set</h3>");
	
		String userName=req.getParameter("userName");
		Cookie coo1=new Cookie("userName",userName);
		coo1.setMaxAge(24*60*60*30);
		resp.addCookie(coo1);
		
		out.println("<a href='"
		+req.getContextPath()
		+"/get'>"
		+"查看Cookie</a>");

		out.println("<p>上下文路径->"+req.getContextPath()+"</p>");
		
		out.println("</body>");
		out.println("</html>");
	}
	
}

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Test_getCookie extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		doPost(req,resp);
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		req.setCharacterEncoding("utf-8");
		out.println("<html>");
		out.println("<head><title>Test Cookie</title></head>");
		out.println("<body>");
	
		out.println("<h3>测试get</h3>");
		
		Cookie[] cos=req.getCookies();
		Cookie c=null;
		for(int i=0;i<cos.length;i++){
			c=cos[i];
			if(c.getName().equals("userName")){
				out.println("用户名"+c.getValue());
			}
		}

		out.println("</body>");
		out.println("</html>");
	}

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
	<servlet>
		<servlet-name>Test_setCookie</servlet-name>
		<servlet-class>com.zhiqi.Test_setCookie</servlet-class>	
	</servlet>

	<servlet-mapping>
		<servlet-name>Test_setCookie</servlet-name>
		<url-pattern>/set</url-pattern>
	</servlet-mapping>
	
	<servlet>
		<servlet-name>Test_getCookie</servlet-name>
		<servlet-class>com.zhiqi.Test_getCookie</servlet-class>	
	</servlet>

	<servlet-mapping>
		<servlet-name>Test_getCookie</servlet-name>
		<url-pattern>/get</url-pattern>
	</servlet-mapping>
	
</web-app>

【模型10】Session会话

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>

<form method="post" action="/Example9/f">
<input type="submit" value="点击" />
</form>

</body>
</html>

package com.zhiqi;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
import java.util.Enumeration;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class TestSession extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		doPost(req,resp);
	}
	public void doPost(HttpServletRequest req,HttpServletResponse resp) throws IOException{
		resp.setContentType("text/html;charset=utf-8");
		PrintWriter out=resp.getWriter();
		out.println("<html>");
		out.println("<head><title>Test Session</title></head>");
		out.println("<body>");
		
		HttpSession session=req.getSession();//创建Session
		Integer count=(Integer)session.getAttribute("count");
		if(count==null){
			count=new Integer(1);
		}else{
			count=new Integer(count.intValue()+1);
		}
		session.setAttribute("count", count);
		session.setMaxInactiveInterval(3600);
		//访问次数
		out.println("您已经访问了  "+count+"  次<br>");
		if(session.isNew()){
			out.println("这是一个新的Session<br>");
		}else{
			out.println("这不是一个新的Session<br>");
		}
		//返回一个包含分配给该 session 会话的唯一标识符的字符串
		out.println("getID<br>"+session.getId()+"<br>");
		//返回客户端最后一次发送与该 session 会话相关的请求的时间
		out.println("getLastAccessedTime<br>"+session.getLastAccessedTime()+"<br>");
		out.println("格式化后的getLastAccessedTime<br>"+new Date(session.getLastAccessedTime())+"<br>");
		//返回该 session 会话被创建的时间
		out.println("getCreationTime<br>"+session.getCreationTime()+"<br>");
		out.println("格式化后的getCreationTime<br>"+new Date(session.getCreationTime())+"<br>");
		//返回 Servlet 容器在客户端访问时保持 session 会话打开的最大时间间隔，以秒为单位。
		out.println("getMaxInactiveInterval<br>"+session.getMaxInactiveInterval()+"<br>");
		//返回 String 对象的枚举，String 对象包含所有绑定到该 session 会话的对象的名称
		Enumeration e=session.getAttributeNames();
		while(e.hasMoreElements()){
			String name=(String)e.nextElement();
			out.println("name<br>"+name+"<br>");
			//返回在该 session 会话中具有指定名称的对象
			out.println("getAttribute(name)<br>"+session.getAttribute(name)+"<br>");
		}
		
		out.println("</body>");
		out.println("</html>");
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
	<servlet>
		<servlet-name>TestSession</servlet-name>
		<servlet-class>com.zhiqi.TestSession</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>TestSession</servlet-name>
		<url-pattern>/f</url-pattern>
	</servlet-mapping>
</web-app>

【模型11】Filter过滤器

	@Override
	public void doFilter(ServletRequest sreq, ServletResponse sresp, FilterChain fc)
			throws IOException, ServletException {
		HttpServletRequest request=(HttpServletRequest)sreq;
		HttpSession session=request.getSession();
		Object o=session.getAttribute("userNames");
		String path=request.getServletPath();
		if(o==null && path.indexOf("login.jsp")<0){
			RequestDispatcher rd=request.getRequestDispatcher("login.jsp");
			rd.forward(sreq, sresp);
		}else{
			fc.doFilter(sreq, sresp);
		}
	}

	<filter>
		<filter-name>loginFilter</filter-name>
		<filter-class>com.zhiqi.filter.LoginFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>loginFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

　　此时如果获取不到session对象啊会把主页mian.jsp转发

【模型12】HttpSessionAttributeListener监听

package com.zhiqi.listener;

import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;

public class SessionAttributeListener implements HttpSessionAttributeListener {

	@Override
	public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {
		System.out.println("添加的属性名"+httpSessionBindingEvent.getName()+"添加的属性值"+httpSessionBindingEvent.getValue());

	}

	@Override
	public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {
		System.out.println("删除的属性名"+httpSessionBindingEvent.getName()+"删除的属性值"+httpSessionBindingEvent.getValue());

	}

	@Override
	public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) {
		// TODO Auto-generated method stub
		
	}

}

	<servlet>
		<servlet-name>LogoutServlet</servlet-name>
		<servlet-class>com.zhiqi.web.Logout</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>LogoutServlet</servlet-name>
		<url-pattern>/logout</url-pattern>
	</servlet-mapping>