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>

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